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AN ELEMENTARY ASTRONOMY
FIRST EDITION
by H. MATTISON
Classic Literature Collection
World Public Library.org
Title: AN ELEMENTARY ASTRONOMY, FIRST EDITION
Author: H. MATTISON
Language: English
Subject: Fiction, Literature
'LJLWDOPublisher: World Public Library Association
Copyright © 20, All Rights Reserved Worldwide by World Public Library, www.WorldLibrary.net
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i
..
AN
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r
~.
~.
ELEMENTARY ASTRONOMY,
•
. I'OK
ACADEMIES AND SCHO.OLS •
•
ILLUBTllATED BY NUllEB.OUB OlllGINAL DIAGRAMS, AND ADArI'EC
ro USE EITHER WITH Oil WITHOUT THE AUTHOR'S
LARGE MAPS.
BY H. MATTISON.
~
i
I'IPTB BDITIO.-TWBLI'TK ...OUI.A..D.
,
-
NEW YORK:
PUBLISHED BY HUNTINOTON AND SAV AGB,
216 PEARL STREET.
CINCINNA.TI :-H. W. DBRBY
1849.
&,
CO
PREF ACE.
,
. Tu P~Dt ie, emphatically, an ap of _tili". Bowe.er profollDd
and accurate a book. may be, its career will be brief and ita circulation
limited, unle. it .. eminently prGctieGI, and wi_lyadapted to its purpose. Heoce it often happeD8, that pel'8OD. of andoubted abiliti. as
men of learning, have utterly failed in their attemPts to produce avail ..
able ten ..boob in their feapective departmentl of lItudy.
Exper~ence
•
.. a teacher, and tac~ as a compiler, are .. important
to the author of a IChool-book, 88 a koowledge of the subject upon
which he writes. And even with aU ,theae endowments, few writers
•
•
of elementary worb are satisfied with their own production. till actual
use in the school..room hu shOWD whereio they are defective, or waDtitJg in adaptation, and of what improvemenu they are capable. Hence
almost every new school-book is "reviled and improved," before it
passes to a second edition.
The ELEIIBHT...Y AII'BONOXY and AaTaoNOliloAL MAN han now
been before the public about eighteen mont,ba, during which time about
0fI6 tloU8tJftd .et. of mil", and tt'll tAouGnd oopl. of the book have
been BOld. These have gone into Ule in ..Imost every state of the
U mon, and every grade of sChools, from the -Common School to thea
University. One set of maps, and a supply 'Of book., were ordefed by
a Scotch lady, who had WJed the work iD her own eeminary in thla
country, to be used in a mOdel school in EdiBburgh, ScotJaDd.
During the put year both the author and publilhe.. have taken
.pecial pain. to aaeertain the views of "."ctieG~ t,GcA.,._, w~..ere
tJCtfMJlly wing the worltt aDd to obt~n any auggeitioDB which might
be of .nice in renderiDg fRture edido_ more perfect and complete ;
and the unanimity and cordiality with, which all wch have commended
the WQIK, ia truly gratifying and encouraging. A few alterati0D8 and
improvements have beeD IUI'~,
80me of which we have endeavored to profit.
SooB after the Second Edition was publilbed, we weM requested by
teacben in Philadelphia and eiliewben, to ~paip a IIIlit of appropriate Qu._tiou on Uhe LeMa. A.ccordiDglyJ t.heee appeal in the
b,
(
PUI-A.OJl.
Third Edition, in the form of an Appendix, and are lItiU continoed
They can, therefore, be uaed or not, at tbe di8cretion of the teacher.
.
To adapt the work to private leamen, and to school. that c&llDOt
parchue the large maps, it is DOW _eel with the large maps in miniature, intel'8pemed among the le8IOIUL Theee beiDg exact copies of the
Originals, though upon a .maller leale, we have not only a magnidcent
let of charts for lectu1'e8 and illWltratioos in the school-room, bot each
learner has a set of tA, . . . flllJfM in hie text-book, and can, ther.
fore, pursue biB .tueliea either with or without the large maps, acCOl'Ging to circumstance& Tb"e text, however, bu not been altered; ..
that the book is still perfectly adapted to the large mapa, and CaD be
uaed with former editiooa, as if it had not been illWltrated.
10 a few instances the language of the book nec8l8arily sup.,..
the large maps to be in view, all OD pages 32 and 201; but these 08881
are rare. AJJ the large and lIIDall maps are the llaJDe, if the test •
adapted toJo one, it ml18t be to both.
The diagrams are in.ned where they are first referred to, and are
made to face the right, 80 U to be e..ily kept in view while Itudymc
the leIBoD8 that follow.
It is confidently belieYed that the peculiariti. of thi. work are I1lOh
as will oommend it to geDeral favor, and laoure for it mcreuing popularity, and an en viable and luting reputatioD.
1. In the first place, the fMtAod or plcn of the work is eminently
original. "One thieg at a time," and" eyery thing in its place," baft
been the author's mottoee. It begins at hom«>, or with the Solar Sya&em, and ends in the more distant or Sidereal Heavens. The Earth
is treated of astronomically, or as a/ planet; and iD8tead of digre.in,
wben we come to her, to coDiider her MOOD, aDd the phenomena of
Eclip881 and Tidea, theee subjects, and all othen pertaining to the
lteCoDdary planets, are reeerveel for their appropriate place&. Tide.
and Eelipee8 ue by no means peculiar to our clobe ; why, then, should
we aacrifice a philoeophical cl...moatioD, and foist in the MOOD, with
the lubjects of Tid. and Eolipeee, before we have done with the pri--
..
marl.?
Another prominent feature in the arranpmeDt, anel one tbai
will please every practical Le~oher, is, that tbe !GCu of tl~ .eN,are cl.8,ified. Instead of naming a planet at the bead of a leMOD
or chapter, and then giving its diltaoce, magnitRde, deDBity, veloeily,
periQd, &c., all miDIleel together upon the llCUDe page, violatiDa
&be lairs of ~ia1ioD. aDd .tting at defiaDce the eftOrta ~ mem-
I
..
PBZI'ACJI.
ory, all fact. 01 the _me kiDd are here cl&lled together; •
6
that
the whole lICience is reduced to' 8)'8tem aDd order. For iDBtaDce, wb_
the Primary Planet. are taken ap, the fiI'8t le.on following is deyoteci
to their fttlfR4!. and _'roftf1fRic.1
~. Il80000 to their tl~.
ttJace., &0., 10 that their temperature, mapituct., deaaiti_, perioda,
8e880D8, &e., constitute 10 many dilttiDct le.o... ; cODIeClReDtly, th.
facts can not only be read, but let.mletl and r",...6.,fL
2. A secoDd characteristic of the work is, that it .. more lully mu.ttated than lUly other work, of the IllUDe fonn, thai bu ev~r beeD publiBbed in tb. country. ADd yet it iI Dot a mere picture-book, in
wbich a noble lCience hu been trifled with, aDd 8&Cli6ced to a deeire
to catch the eye, aDd eell the book. The ide. 01 devoug fJ'fery other
page of a scientific work excluaively to iIlO8tratio., and at the I8IDe
time doiDIJ any kind" of justice to the .object on the iDtermediate pagel,
is altogether chimerical. It would be too mucb like a farm, one.half
of which W&8 devoted to a 8ower.prden; or like IIOID8 of our ill...
trated holiday-papel8.
3. The leading desiga beiDr to furailb aD avaiJabie text.book ".
Aatronomy for Common Schools and Academiea, 18 well 88 for pri"Yate students, tbe author baa confined hi~lf mainly to what may be
caUed the fact. of the aaience, or in other words, to the r,,,,lt. wbi~b
have been arrived at by the labore of the ob8ervatory IUld tbe 1'8aearchea of the mathematician. The atructare aDd Wte of inl&rumeDte,
and the calcu~tjona and p~ by which the faots of the ecieoce
are arrived at, are deeignedly omiUecl. ' Theee may be neC8ll&l")' in
text-boob for our higber, iD.titutiou of learning, but they caD neyer
become legitimate lubjects of primary iustruction For similar reaIOn., the mythological history of the lOieDce hal been dilcarded.
4. We have adapted the work to the present ltate of the ecieuce by
embodying the etatistice of eeveral ..., plGuu, recently ciUIcoveJ'tid,
the recent observatioD' of Lord Ro.t upon the MOOD and the diatlWt
N ebul." and the IUbliGle and almost overwhelmm, anDOUDcement of
Midler in iegard to ille " Central Sun."
5. When used in connection with the large maps, the work combiDes all the advantagee of blaokboard iUustratioDl, with tbe mOBt pa..
tieDt study of a text ..book. . All the diagrams in the book are found in
the corresponding maps, upon a very large .cale, 80 that every explanatiou from the mapa, by the teacher, aerves t.o render the diagrams
in tbe book more interestiDI and intelligible. Another strikillg ad- l'utage of this method of teaching Aatronomy la, that whatever ilh.·
.,..z.;
8·
PBBJ-AOB.
tratiOIUJ are given by the toaeber, beneftt the whole ell. alib,
•
without the labor
repetition to each echolar, over a diagram iD
the book. Thia ..viDI of time aDd repeated explanations to difFereot pupils, wiD be read,ily appreciated by every practical jnatructor~
Again, many of theee draWiDP are ""irel, origiul, and in the opiaion of competeDt jl1da-, better calculated to conyey a correct and permanent idea to the miDd, than aDY that baye heretofore appeared.
6. Though adapted to QII8 with the .riea of large maps, it is, at the
laDle time, complete in iteelf, and can be used 88 well independently of
them 88 if it had DO connection with them whatever. Thi8 i. an important advantage.
7. To all tbeee we mJly add that, all thinp considered, it ill ~
"lNape.' text·book of Astronomy that has ever been publi8hed ill
America. A cl. . of thirty 8Chol&rl can be supplied at retail with a
. . of the large map', and a book for each for 130. A school of 100
can procure a Bet of map' and a book for each pupil for 165. ' If procured at wholesale prices, a eet of mapa Cor the 8Chool-room, aDd •
hook for each pupil, would cost Ita than ftfty ceil" per echolar; and
the IDOre scholaJ'l, the Ita the expen8e to each. Where, then, we
uk, can tbe same facilitiea for aoquiring a knowledge of Astronomy
be procured for the ..me money 1 We commeDd this cOnAideration
eepecially to thOle having charge of large echool8 in our citiee and
allewhere.
Such are aome of the peculiaritiea of the ELBlllurr.IlY ABTaONOIIY;
aDd upon theee we can lafely I'fJIIt oar claiml to public patronage, in
lending it forth to the world. ID ita preparation for the Prell, the aGthor has availed himaelf of all the hel.. within his reach. He h.
OOD8Ulted all the boob UPOD the wbject that were available in th.
COIIDtry t U well .. many practical teacheJ'll, and gentlemen of acknowledged ecientific abilitieL But while on the one hand he has used
boob as writen generally uae them, namely, &8 IOUlCe8 of knowledge,
aDd haa advised with meD of learniDg and experience i~ regald to
many particulars, the author feels bound, in jU8tice to himaelf, to claim
for hie work a good degree of originality; and to .y, that whether
good or bad, it is, iD the main, his own, and not the work of another.
It ill only D8CeII&I'J to add, that the ltatiatica in the ttlble& are generally giveo in round DumbelB, and aceonliDg to what. were considered
the highest authoritiee.
or
!law Yoalt, Ja. I, IMg.
"1
-
.
TO TEAOHERS.
-
Tn"R are .veral way. in which thiI work may be used to .d-
yutage.
1. It may be Itudied prec_ly like aoy other text-book, and the
pupil examined by the printed, or by extemporaDeoUIJ question&. Thill
ia the usual method in tbose lCbools whicb have not the large maps.
and in academies and eeminaries where the pupil. Itudy in tbeir rooms,
and aee the large mapa ooly in the recitation-room.
2. Wherever the large maps can be obtained, and the pupils aU
lItudy iu tho lame room, and only during ecbool bours, Astronomy
lhouJd be made a K,ner.l I~trciH two or three timea every week.
The mapa to which the leaaoDI refer, should be 8uspended on the BOuth
side of the room, if practicable, (to answer to the natuml position 01
many of the obje~" in the heavens,) and the lelllOD studied with cooittant reference to the maps. Tbey are 10 much more attractive and
imposing, and tbe figures 80 mtlch more distinct and prominent thaD
the cuts in the book, 88 to give them a decided advantage over all ordinary illustrations. They should, tberefore, be procured wherever
practicable, and used in connection with this work.
3. A third method of ueinr the work, is to 1IIe it a•• rIdding-boot
two or three dmee a week, either with or without the Jarge eharts. II
these are ill the school, theyebould be It18peDd~d before the cia. during the exercise. By tbil method the pupil wil1leam to pronounee
acientific terDll correctly, to read figuJ:ee with facility, to read with atteDtion, and to remember what he read-. Beeidee, DO extra tjme will be
required. The pupil is leaming to read, and at the same time studying
a science. By tbe 1188 of the mapa the teacher can illustrate the leMolKI
as he goel along, and a wholesome interest wUl be 8U8tained throughout. The questioos in the Appendix will be found convenient in reYiewing tbe J88IOD& Teachers will find tbis aD efficient and delightful
method of teaching Astronomy.
4. Several of the tables in the first part of the work should be committeod to memory; lucb as the names, dialances, magnitudes, &c., of
tbe primary planetS. If Uie teacher prefer, they may be learned by
concel1 recitatloo&'
....
8
TO TEACHBRS.
5. Tbe UUonomicalligoa in Leaaon 7th should be draWD upon the
blackboard by th'e leamer, and explained. It would aJ~ be useful
for him OCCasioDalIy to draw map' of di1FereDt celestial qbjects, from
memory.
&. In lOIDe CUEI8, the whole IQbject may be preeented orally by the
teacher, in • aeries of evening lectoree, following the C01l1'8e 9f the
book; but this .bowd rather be in tJddititm to the replar .ady dorin.
IChool hoUl'l, than a mbetitute for it.
7. After aU, much win depeod upon the judgment and ingeouity of
the teacher, aod the intereet he takes in the subject. Bound leaminr
caD never be acquired, by any mode of teaching, without thought and
attention. N eitber can any particular oouree be struck out that wiD
be adapted to all kincts of echooll, and to every part of the country.
8. To lucb teachel'l 88 have never studied tbis acien08, (and there
are .,me of this 01. .,) we would say that the work iI lpecially adapted to your circulD8taooee. It is strictly elementary, DO extraneoll8
and abstrule matters darkeD ita pages, and it is not 10 voluminous ..
to require a year to
through it. Y oq will fiDd DO dimculty whatever iJl teachiol the lCienoe witb thil work, even though you have
Dot previou~ly taught it; and a cia. iD thil deligHtful IUld sublime
lCience will be the surest means of adding to your pl'ellent intellectual
&torel, a knowledge of this ,important branch of study. If auy new
motive be neceasary, let it be remembered that no Dew audy is 10
rapidly goill, into the primary echooJa of the country, 88 that of De-·
ecriptive A.8tronomy; and the time ,is .DOt far diataDt when it will be
required to be taught in every achool-house in the land. Be encouraged, then, to enter upon this Itudy. Organize your clUB at ODce,
and launch oot tI01D for a knowledge 01 those fl• • of 'worlda that ail
the upper deep. U entered upon in the Ipirit of a teGel", your PlOIreal will be rapid, your voyage delightful, IIl1d IUOCe18 certain.
With these luggeitioDB. the work is now comlJlitteci to your hlUld&
Baving been formerly identified with you 88 a practical teacher, the
.athor expects the co-operation of hiB profeaaiooal friends, in leDderiD,
the work usefol to the riaing generatioB, and in promot.iDc the interests
of that Doble lCien08 to which it is devoted.
ro
I[7For a de8erlptloll of the Large Kapil, pr1cea.
ealar at the end of tile Book.
.~,
11M CIr-
CONTENTS.
INTRODUCTION.
~
I.
. I.
I.
'I
0.. •..•...•..••.• ••••••••
...
ABtrooomy-ite Nature .. a ~ieDC8" ••
Ancient li~ of Aetrouomy-the Ptolemaio 111..,...........
DirHcult ies of Uie Ptolemaic Theory. ••••••••••••••••••••••••••••
The (;ol1em icao S)'IItem..,. . • . . . . • . . . • . • • • . • •• • • • • •• • • • • • • • • • • • • • •
FirBt Gnaad Div.oDS 01 the U DiveI'll8,. • • •• • • • •• • •• •• • • •• • • •• • • • •
11
11
I'
II
11
PART I.
OP THE SOLAR SYSTBM.
CHAPTER I.
CLAMlPJa.TION 0,. THB lOLl. mDta
.. '!be Sun. Plue&a. PriIoariee. SecondariM, &0., ••••••••••••••••• II
CHAPTER II.
ow
THK
PIlIMAa, I'LlJIr8"N.
,. Names and 8.1«" of the Primary Planeta, .••••••••••••••••••••••
8. Distances of the Planets from the 8UII, ••••••••••••••••••••••••••
10 DeKfet-lil. MinutN, and ~ecolld. explained, ••••••••••••••••••••••
10. A nt{U11&l' Distances, Ma«Ditudta.8, &c., •..••••••••••••••••••••••••
11. The ~UII . . Been from the different Plaoeta. •••••••••••••
Ii. PhilO8Oph.J of the Diffusion of Li"ht, .•••••••••••••••••••••••••••
13. I~il(h t and Heat of the leveral Planets, ••••••••••••.•••.•
14. M ~n i I ude of the Planeta, •••••.•...••••.••••••••••••••••••••••••
15. Relative M~Ditude of the Sun and Planets, •••••••••••.••••••••
Je. Comparative DeD8ity of Ule Plauete, ••••••••••••••• : •••••
17. A ltrllctioll of the Plaoe~"" ••••..•••••.••.•••••••••••••••••••••
18. Periodic RevolutioDll of me Planets, ............................. .
I Hourly Motion of the Planets in their Orbita, .•••••••••••••••••••
10. L"".entripelaland Centriful{al Forces, .•••••••••.••••••••••••••••••
'II. Diurnal RevolutiODl of the PJaoets, .•••.••••••••••••••••••••••••
ti. 'rru~ FiJ{ure or tile Planeta, .••••.•••••••••••••••••••.••••••••••.
o •••••••
0 ••••••••
0 ••••••
~.
The I!:cliptiC!t
o.
II • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • ,
••••
t4 Th(ll Poles the Ecliptic, •••••.•••••••••••••
15. Oblic\uity of the ~liptic, ••••..•...•••••.•••••••••••••••••.••••••
18 1~he Zodiac •••••••••••••••••••••••••••••••••••••••••••••••••••••
n.
1'i~nl
0 •••••••••••••••••••
of ttle Zodiac••.••.•••.•••..••••••••••••••••••••.•••••••••
18. Not.lee-- Ascendin, a..cl l)eacendiu".
0 •••••••••••••••••••••••••••
II. Tra,nBiw......................................................... .
••
•
.
IT
18
30
31
•
31
D
JI
••
37
31
31
•41
48
41
•a
30. Trull.ita of Mercury, •••.••••••••••••••••.•••••••••••••••••.••••• 44
11. Transits of VflnU8~ •••••••••••••••••••••••••••••••••••••••.•.••• a
a. Incl i nation of the urbita of the Planeta to th" Plue of the Ecliptic,
41
13. Ct-1t>8f illl Latitudea .•.•
34. C..elf'8lial IAlll{itud(II, • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 4'7
.-
0 ••••••••••••••••••••••••••••••• :
•••• 0
••••
35. l..onl(itude of the AacencljnJ( Nod. of the Planetll, .•••••••••.••••
...
38. C.onBtella t ione of the Zodiac, ............•.•••••••.•••••••••.•••• 10
01
17. The ~uuttl Apptlrcnt Motion in tbe Ecliptic, ••.•• ·•••••••
0
••••••••
..
10
CONTBNTS.
t-oa
.
.....
38. SucceMive Appearance of the C9ostellatioDi in the Nocturnal
fleav8D1, •••••.•••••••••••••.•••••••••••••••••••••••••••••••• II
•• VisaKreement between the Months and SigDB,. • •• • • •• • • • • • • • • • •
40. The ~uiDoxest.. . • • • . . . • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •
41. Prece8Bion of the !:quinoxee...... • • • . •• • • • • • • • • • • • • • • •• • • • • • • • •
a. The ~l8tiCM,.. • • • • • • • • • • • • • • • • • •• . •• • • • • • • • • • • • • • • • • • • • • • • •• • •
43. Tile ColurtllJ ••• • •• • • • • • • • • • • • •• ••• • ••• • •• ••• • ••••• ••••••• .• ••••
". Ellip.tic~ty 01 the P1~ets' Orbita........ •••••• •••••••••••• ••••••
45. P~rlhellon and Aphelion, ...••.•.••.•••.••••••••••••••' • • • • • • • • • •
46. Eccentricity of the Planets' Orbitl........ ..•. ••••••••••••••••••
41. Phil.-ophy of the Sea.aona, •••••••••••••••••••••••••••••••••••• ~
48. The tsun'a I>eclination, • • • • •• • • •• •• • • • • • • ••• • •• •• ••••• • •• •• ••••
49. Right Aacension, •••••.••.. '. . • • • . • • •• • . • • • • •• •• • • •••• •• ••• • ••••
10. Inclination of the Axes of the Planet. to the Plane of their . .
8Jlective ()rbits.1: ........•..•••••••••.••••••••••••••••••••••••
It. Seasons of the dinerent Planets,.,. ••.•.•••••••••••••••••••••••••
B. ~n. of Veo1J8,•.••••••••••••.•••••••••••••••••••••••••••••••
1.1. SeIlMlD8 o( Mam, ...••••..•••.•••.••••••••••••••••••••••••••••••
14. Se..,ns of Jupiter, •.•.••..•.•••.•••••••••••••••••••••.•••••••••
u. Se88C)D8 of Saturn, ..
16. CopjunctioD8 and OPP!l8ition of Planets. ..••••••••••••••••••••••
II •
11.
IS.
H.
10.
II.
..
83.
•
•
... •
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•• •
•
•
•
•
••••••••••••
Sidereal and Synodic Revolutions, •••••.•••••••••••••••••••••••
Elonl{8.tioD8 of a Planet, .........•..••••••••.••.•••••••••••••••
When PlanetB are said to be Stationary, •••••••••••••••••• " ••••
Direct and Retrograde MolioIlS, ..••••.••.••••••••••••••••••••••
Relrolrade MotioDa of the Exterior Planets••.••.•••••••••••••••
Venos as Morning and Evening Star, •••••••.•••.••••••••••••••
Phases of Mercury and Venu8, ..•••••••••.•••••••••••••••••••••
.Teleaoopic Views of the Planets, .••••.•••••••.•••••••••••••••••
Telescopic Views of Satun), .......••...•••••.•••••••••••••••••
51
M
14
10
17
18
51
:II
60
81
•
.
II
15
15
trr
87
61
10
'i'I
7t
73
14
71
71
M.
11
85.
81
II. DimeD8Jons, ~tructure. and U&e8 of Saturn'. RiD.., ••••••••••••
81. or the Di8cOvery of the several Planet&, ••••••••••••••••••••••••
CHAPTER III.
01' TIm
"OOND~ILY
••
I'LlJIr8"N.
•• Character aDd Number of the Secondary Planeta,.......... ••••
•• Supooeed Satellite of VeDl1!l' • • • • . •• •• . • • • • • • • • • • • • • • • • • • • • • • • •
.10. Of the Earth's SateUite or moon,.......... .••••• •••••• •••••••••
'1. Chan~ or Phaaes of the MOOD, •••••••••••• • • • • • • • • • • • • • • • • • • •
ft. The Moon'. Path around the Sun, .•••..• .••.• . •••••••••• ......
'71. Revolution of the MOOD'8 Nodes around the Ecliptic,. • • • • • • • • • •
,... Sidereal and Synodic Revolution of the Moon, ••••••••••••••••• ~
11. Revolution of the Moon upon her Axi.,...... . . . . . .. ... . .. . . . . •.
.,.. The Moon'. Librations.. . . . • • . . . . . . . . • • . • • . • • • • • • • • .• ••• . •• • • • •
'IT. 8eamDi {)( the Moon, . • • . . . .. . • • • • • • . • . . • • • • • • • • • • • • • • •• • • • • • • •.
•
14
14
98
.,
98
98
89
II
100
100
18. TeleecoVio Viewa of the Moon,. . •• •. • . . •. . • • •• • • • . • • •• • .• . . . • ••
ft. Phyaical Constitution ot the Moon-Mountains, Volcanoes. At,.
mc.pheJ'e, &c.,.. . . . . . . . . . . . . . .............•......•...... ~ . .• J01
•• ~hJ of the Moon, or Selenography, •••••••••••••••••••••• 103
81. MOODS or Satellites of Jupi~,........ . .......••• ....••. ..•....• 104
B. Satellitel of &tum,.. . . • . • . • • • • • • • • • • • • • • • • •• • • • •• •• • • • • • •• •• •• 105
83. Satellites of Hel8Chel ............. ~ .•••••••••••••.••••••••••••• -101
M. Suppoaed Satellite of Le Verrier'. rlaoet., •.•••••••••••••••••••••. lOT
CHAPTER IV.
f'IIILOIOPBY
or
o.
SOLJIIIIBI.
D. Nature and Call1e8 F.cli............. • ••••••••••••••••••••• a 101
M. Character Extent, and Duration of Solar Eclipaee, •••••.••••••• 110
11. EcliIJeel 0 1the Mooo, .••••••••••••••••••••••••••••••••••••••••• 114
j
:
CONTBNTS.
LI...or
.
the Time aod F!equency tI Eel....... . . . . . . .. . . . . •. • . . • . . ..
, at. &.Ii.... or ()ccaltalioDi of the S&aiW, ••••• • •• • •• • •• • • • • •• • • •• ••
10. F.clipaee of Jupiter'. Moona........ . .......... ....•... •....•.•••
II. &li.- of Salorn and Herlchel, ••••••.••••••••••••••••••••••••
88.
11
....
J11
111
118
111
CHA.PTER V.
PJIILOIOPBY ow ".. TID. .
B. Nature and Call1f!J8 of Tides, ••
13. ~«iD« of the Tide-ExcW'lione in Latitude.............. • . • ••
SM. ~~g and Neap Tidee-Prof. Daviee' Th.eoI'J, •••..••••••..••••
15. Other ine.qualitiea or the Tid4t"J .••.••••.• • • • • • • • . . •• • • • • • • • • • ••
II. Kobon of the Apeidee of the moon'. Orbit, •• • • • • • • • • • • • . • • . . • ••
II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
I_
1.
1.
111
lIT
CHAPTER VI.
ow COIIBTL'
1'1.
18.
II.
100.
General Delcriptfon of Cometary BodiM•••••••••••••••••••• : • ••
Mapitudel, Veloci~ and Temperature of Cameta,. •• ••• • ••••
Penods, Distances,
N umber of Comets, • • • • • • •• • • • • • • • • • • ••
Direction, Orbits, Bncl Nature of Cometa.. • • • • • • • . • • . . •• • • • • • • ••
1_
1.
1M
1_
CHAPTER VII.
ow m8 IUN.
101. General Remarks ~ing the Sua-ita Magnitude, &c., .•••• 138
101. Spots on the Sun-their Number, ...••••••••••.•.•••••.•....••• 1.
103. Nature of the Solar S~,.. .... ..... . ............. . ........ .... 140
104. M agnjtude of the Solar Spots,. . • • . . • • . • •• • • • . • • • • • • • • • • • . • • . . ••
105. Revolution of the Sun uwn hIS Axis,... . . • . • . •• .• • • •• •• • . •• • • ••
101•.. ~tioDJ...Mot!0Dl!. and Phases of the Sol ... Spoil••••••••••..•••
.. 187. 'PbJBICallA)D8titutIOD of the Sun,.............. • •••• ••••••.• ••••
1118. The Zc:K:liacal Lilht,..... .. .• ..•• .•• . ..... • •.••. • •••••• •••• .•••
101. MotiOD of tile Sun in SJ-ce,.. . . . . . . . . . . . . . . . . . . . . .. . . . . •. •. . . •.
1.
141
141
144
I_
..,
CHAPTER VIII.
1II1C.LJ...\N.OUl aBMAILK8 UPON THE 80ua IUTUL
IlO. Nebular Theory of the Origin of the Solar System, .• • • ••• • ••• •.
111. I..awa of Planetary Motion, .. . . . . . . .. . . . . . . . . ••• . .••• ..... • • • ••
IIi. MiDiature Representation of the ~Iar System, •• • • • • • • • • • • • •• ••
113. Were the Asteroid8 orhdnally 0116 Planet' . . • • •• . •••• • • •••• •• ••
114. Are the Planets inhabited by RatioDal Hemp
'0. .... .... ........
I.
I.
III
111
U8
PART 11.
THE SIDEREAL BRA VENS.
CHAPTER I.
OJ' OONITELUTlONB OJ' ITA...
J15.
116.
117.
118.
119.
110.
111.
J)iatiDguishinR Characteristice of the Fixed Stars, •••••••••• •• •• Jet
~'888ification
of the Stam,.. • • • • • . •• • • • • • • • • • . • • • • • • • • • • • • • • • • • •
Number of the Fixed Stars........................... ~ ••••••.••
Distallces of the Stars, . • • . • • • • • • • • • • • • • • •• • • • • • • • • • • • • • • • • • • • ••
Magnitude of the ~tars,.. .•. • ..•.. . .••.• . .•• . ••.•• ••••• •••.• . ••
List of the Constellatiollfl. . . . •. . .• . • . • • • • • •• . . . . • •• . •• •• • . . • . . .•
Description of lOme of the Prinoipal ConatellatioD8-Zodiacal
181
J83
164 .
J.8I
1M
Constellations... . • . . . . . . • . • . . . • . .. . . . . . . . . • . . •• • •• • • •• . . . . . . .. 170
J•• Nortllem ColJ8t~llatioD8. • •• ••• . •• ••• . •• • • • • •• ••• • •••••• ••• • •• •. 17t
la. Southern CoD8t.ellatiollll, . • • • • • • • • • • • • • • • • •• • • • • • • • • • • • • • • •• • ••• 17-'
12
CONTENTS.
CHAPTER II.
OP DOtJ'IlU,
'YOU....,.6JfD 'l'aIlPORARY ..rAd,
BlNARyanrrt:MI, ETa.
LIIIon
'-
114. Of Double, Triple, and Multiple Stare, .•••••••••••.••••• . •.••..
115. Of ~jn8l'Y and ~th~r AystelJJ8, •••••••••••••••••••••••••••••••••
121. Vantlblt' or Penodical ~tan, . . . . . . •. . . . . . . . . • . .. . . .• . • . . . . . . . ..
111. Tp.mflOrarf ~tan, ..•...•..•.....•••.....••••••••.•.••.....••..•
118. Falling or Shooting StaIB, •• , • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •• ••
180
1st
188
191
lUI
CHAPTER III.
01' OUJ'I'l'KU 01' 8TAJUI, AND DBt1L&.
III. or CluBterw 0( Sta.m, ••••••••••••••••••••••••••••••••••••• .,... •• 114
1111. Of' Nebllle.. • • • • • • •• • • . • . •• • • . . . • . . . • . . • • •• • • • . . • • • • • • . . . •• • • •• 111
APPENDIX.
8'xplaaatioD 01 .&.troDaIDicai Tel1D8. ••• ••••• • . •• • • • •• • • •• • •• • • •• •• . .
INDEX TO THE ILLUSTRATIONS.
Gmat Refractiq Teleecope at Cincinnati, ~hio-troDtinl the Title;
liz-inch RefractiDI Te1eecope, at Mr. Rutherford'. <>beeryatory.
New York-frontiq the Preface.
ftolemaic Theory or the Structue of the UDi'YeJ'B8 ••••••••••••••••••
Q)pemican Theory of the Solar SJ'IIlem ..•
ADpJar Meuarement- Li.ht aod Heat of the Plan... • • . • • . . • .• • •
Relative Magnitude of the Sun and Planets ...••.•.•.
'!be Ecliptic, Zodiac. SiPI, Nodes, Transits, &c•.•••••••• _. • • • • • • • •
Zodiac, EquinOXM, SolBtices, Lo~gitude, Aecendinl Nodee, &c. ••••
. '!be Earth'. Orbit. SUn'. Declination, SeaaoD8,
mclination ofAxM to Orbits; and SeUOI18 of the Phmet8....... •. • .
<»l\iunction, Opposition, Traasita, Phuee of VenDI, &c. •••••• • • • • • •
Teieecopic Vie. . of
Primary PIanef.8o. • • •• • • •• •• • • • •• ••• • • ••• •• •
Batom in hi8 Orbit, Pbuea, Telescopic Vie. ., &0... •••• .••• •• • • . • • •
Ph.... and Teleacopic Vie. . of the Moon...... . • • • •• . . • • • • • • • • . . • . •
0 ••••••••••••••••••• 0
0
•
•
•• •
•
•
•
0
•• •
•
•
•
•
•
•
•
&c..................
the
Solar and Lunar Eclipeea •• ••• • •• ••• • •• ••• • • •• • • • • • • •• ••• • •• •• • • •• ••
1'I1e PhilOlOphy or TidM. • • • • • • • • • • • • • • • • • • • • •• • • • • • • • • • • • • • • • • • • • ••
Vie. . of Remarkable CoIII8IB.. • • • • ••• •• • • •• • • •• • • •• •• •• •• •• ••• • • • ••
Sir
Hemchel'a forty-foot
Clusters of Stars, Binary ~yt4eln8, auu r'~lJule •••••••••••
Lord Rosse'lgreat Reflecting Teleecope ..
William
11
1'7
33
38
49
at
a
•
'1'1
83
.,
101
III
l31
Reftector.................... ...... III
0
•• 0
•••••••
0 •••••••••••••••••••••••••
1~
II
181
1ft
•
- - -
-.o;r--
-
INTRODUCTION.
Le880n I.
IJIftOKOJIT-ITS !fANKB AS .6. ICIBIfCa.
is knowledge systematically arranged, 10 . .
10 be • conveniently taught, easily learned, and readil1
applied.
.
..
ASTBOKolIY Is that science which treats or the names,
distanoes, magnitudes, and motions
the heavenly bodies
-the Sun, Moon, Planets, Comett, and Fixed Stal'8 and
the laws by which tbey are governed .
.All who are not deprived of the ble88ing or sight
have seen tae 8un, moon, and stars. Indeed they are
'Yery familiar objec».t. Now,. by carerully observing
their appearance., and watohing their movements for a
ahort time, every learner may discover or establish the
following raot. for himself; viz.
1. The SUD and Moon appeir nearly or a size, and
much lar8" than any other bodies that we see in the
heavens.
2. The SUD sheds a strong and brilliant light upon
the earth, while the light of the moon ia pale and
Ceeble_'
.
3~ The Sun and MOOD are sometimes near each other,
.... when the Dew mopn is first seen in the west, wbile
at other times, the moon rises hi the east just as the aUD
goel down.
.
4. When the Moon is first seen , east or the SUD, she
i .. very alender; but as she
behind and separates
from the SUD, she grows larger and ]arger till ahe becomes a "full moon i" after which she grows amaller
8cIUCB
or
:+
ralls
2
14
ASTRONOMY-ITS NATURE AS A SCIENCE.
and smaller till new moon again. The horns of the
new moon point to the east, while those of the old moon
point to the west.
5. It is easy to 8ee, by watching the moon tor only
Qoe or two nights, that she is actually moving eastward
8S respects the stan; and she sometimes runs over, OJ'
seems to cover up one, and" put it out for a.time as she
,
goes along.
6. Everybody has notioed the dark linea and spots
upon the surtaoe of the Moon, as if some one had at.
tempted to draw an outline map of some new country
upon her face, showiDg its various islands, continents,
and seas.
.
7. Moat people have seen what is called an ~clip8e ;
or in other words the "partial or total darkening of the
lun or moon, as if some large" objeot was covering .
them up.
"
8. The stars difFer very much in their p.pparent sizesome appearing large and bright, while others are 80
small and taint as to be 8carcely' perceptible.
9. Most of the stars seem to" keep the sam~ ,distanoe
from each other, and to ocoupy the same positions with
reference to each other from age to age. But there are a
few that are constantly wandering along eastward, as
it were trom star to star,. till, like the MQOD, they
traverse the whole circuit of the heavens. Dl&ring this
journey, they sometimes stop for a while, and even fall
back west.ard, but they soon resume their ..route again
with an accelerated motion, and hasten eastward over
the celestial concave.
10. One star at least is west of tbe sun Cor a time,
and rises beCore him, «;>n which account it is called the
Morning -Star. But this same star, may at other times,
be seen east of the SUD. At this time sne may be sp-en
in the west after the SUD goes down, and is then called
the Evening Star.
11. The .stars in the northern portions of the heavens
aeoer Bet, but seem to revolve around what is called the
North Pole star, from night to night, and from year to
year. By ranging by a stake or some other permanent ,.
"
~
'-~
.ANCIENT HISTOB.Y 0., AITKO.OIIY.
15
object, on a clear evening, it will be seen in a sbort
time. that all the stars below the North Pole star Beem to
be moving euttDard.
12. During the winter, the sun is quite low down in
the south; but in June and July, he is almost directly
overhead at twel ve o'clock, even as fa r north 88 the
United States. These, and maDY otber curious things
respecting the heavenly bodies, may be observed with
the naked eye, or without the aid of telescopes. It was
in this way that the ancients studied astronomy. By
oarefully watching the heavens, they learned ODe fact
after anQther, respecting the SUD, mOOD, and stars, and
when these facts were put together and arranged in systematic order, they constituted the Science oj .A6~
Lesson
~.
ANCIENT HISTORY OF ASTRONOMY-TBE PTOLEMAIC THEORY.
(Map 1.)
The oldest records of astronomicai science are found
in the Holy Scriptures. We there read of the creation
the sun, moon, and stars, and thf' commencement
their revolutions. In the Book Job, which was written
fifteen hundred years before Christ, we read of "Arct,,nu, Orion, and Pleiades, "-stars or cl usters of stars that
bear the same name ~t the present 'day. Weare here
taught, also, that our world does not rest upon some vast
and strong foundations, but that the Almighty " hangeth
the earth upon nothing."
The prophet Amos speaks of the "seven stars and'
Orion." 8ev~n hundred and thirty-three years before ·
Christ, and of the phenomena of day and night.
The Greek philosopher, Pythagoraa, taught astronomy
about five hundred years before Ch rist, and the Egyptian
philosopher, Ptolemy, in the second century of the Christian era. Ptolemy constructed a regular system or theory
of Ifstronomy, by which he proposed to account 'for all the
appealrari~. and motions of the heavenly bodies. '
or
or
or
"f
•
,
'1
16
I
TIm l'TOLBIU.IC TBBOllY.
The PTOLBIIAIC SYSTDI, 80 called from Ptolemy, its
author, is the subject of Map No.1. It represents the
earth as located in the centre of the universe; as being
perfectly at rest; as a plane instead oC & globe; and as
inhabited only on one of its sides. Some supposed die
. earth to float upon an abyss of waters; while others be.
lieved that it rested upon the head of an eOQrmous serpent
or dragon, as represented on the map. Ptolemy taught,
.190, that) the 8UD, mOOD, planets, and stats revolved
around the earth, frOID east to west, as they appear to do,
every twenty-four hours. To account for their passing
over the earth without falling down upon its surface, it
was supposed that the heavenly bodies were supported by
vast arche8 or IwllorD aph,ere" in which they were firmly
.et like a diamond in a ring.
But "as the SUD, moon, planets, and stars were not a11 at
the same distance from the earth, it was supposed that
there were several of these spheres placed one above another-that the Moon was in the first, Mercury in the
eecolld, Venus in the third, the Sun in the fourth, Mars in
the fifth, Jupiter in the sixth, Saturn in the seventh, aod
the Fixed Stars in the eighth. The anoients had no
knowledge of Herschel, or Le Verrier.
Mercury, Veo'us, and the Moon, were placed in the
three lower spheres, because they were sometimes seen
to pass between the earth and the sun. But Me.rcury
aDd Venus sometimes go before the sun, and sometimes
follow after him. To account for this" it was supposed
that besides the great circle of the heavens around w hioh
they passed daily, they had other smaller circles withiD
their respeotive spheres, in . which they revolved at the
same time. These the a!1cients called ~lu. They
may be seen on the Map, In the second or sp_ of Mer.
oury.
To acoount Cor the rapid westward motion of these
ponderous spheres, it was believed that the neceSS81 y
moving power was applied in some way to the upper
sphere, above the fixed stars; and that this sphere COAlmunicated its motion to the ODe immediately b,e.neath OJ
within it, and 10 on down to the lower sphere. !fhis, h
17.
DIPPICl1LTIBS OP TBB PTOLEMAIC TBBO.Y.
#
was thought, moved slower than the rest, .s the mOOD
or
•
constantly fell back of the SUD. To allow the light
the stars to pass down to the earth, it was supposed that
the sever~l concentric spheres rising one ah9ve another,
were made of the finest cry,tal, and were perfectly transparent. The space above the fixed stars was designated
as the blissful abode of departed spirits.
On the map, the spaces between the white circles represent the several crystalline spheres. The sun and mOOD
are represented as going ~own in the west, 'he mOOD
baving fallen a little behind the 8UD, as when we first see
the new moon. Mercury and Venus are near the SUD, &I
they always are, and Mars, Jupiter, and Saturn on the
left. On the right "is seen a comet passing down toward.
the sun.
Such is the Ptolem4ic TMDrJ of the structure
the
Universe.
or
Lesson 8.
DIPPIC11LTIBS OP THE PTOLBMAIC TBKOB.Y.
(Map'l.)
Besides the 01 umsiness of the machinery, it W88 at.
tended by numerous difficulties :which ita supporters could
Dever explain or obviate.
~
1. It could never determine what upheld the earth.
Rooks and mountains could not float upon water; and if
they could, what upheld the water' Some imagined that
the earth was upheld by a huge 86r:JJe"', resting upon the
back of a tortoise, as represented in the map. But what
upheld the tortoise'
2. It represented many very large bodies, &I the SUD
and some
the planets are DOW known to be, as revoly.
ing around the earth, a com'paratively small one.
a. It adopted the most difficult and unreasonable plan
for lightipg and warming the earth, and producing day
and nig~t: - Taking the sun around the earth every
twenty-four houra, W88 like carrying a fire around a
or
2-
18
TBB COPBllMICAN STInK.
•
person who was cold and wished to be warmed; instead
of his turning himself to the fire as he pleased.
4. The Ptolemaic theory would require a motion inoonceivably rapid in all the heavenly bodies. As the
aun is ninety.fi ve millions of miles from the earth, the
entire diameter of his sphere would be one hundred and
ninety millions of miles, and its circumference about six
hundred millions. Divide this distance by twenty.fourthe number of hours in a day-and it gives tUJent,-fifJ,
aillion "tile. aft hour; or sixty-nine thousand four hundred and Corty. four miles per second, as the velocity oC
ahe sun!
" This theory gi ves a still more rapid motion to Mars,
Jupiter, Saturn, and the fixed stars. It would require
the nearest of the latter to move at the rate or near four- .
"m thouBand milliO'll,8 of mile. per a6corul, or seventy
thousand times as swift as light, in order to accomplish
ita daily course.
But with all these difficulties in its way, the Ptolemaic
theory was generally believed till about the middle oC the
.ixteenth century, or three hundred years ago.
Lesson 4.
THB COPERNICAN SYSTEM.
(Map
S.)
or
or
About the year 1510, Niclwlatu Copernicu,
Pru88ia,
. taking some hint perhaps from the writings
p,tIaogo.
ru, discovered what is now generally received as the
true theory of astronomy, and called aft~r its author the
Corpemican Syatem.
The COPBRNICAN SYSTBM attributes the apparent daily
motion of the sun, moon,. and stars rrom east to wes\, to
the actual motion of the earth on its axis from wes' to
east. Though the heavenly bodies ,ee". to move; yet we
often transfer our own motion, in imagination, to other
bodies that are at rest; especially when we a~ oarried
"apidly along without effort, u in a carrisge, steamboat,
".
\
1
n_IT a_AXD DmSIOX8 01' TID VKIV.....
19
or railway car. It places tbe SUD in the centre or a
ayatem or worlds, of which the earth is one. It gives thel'll
a reyolutioo around their common centre, by which the
1888008 are produced; and anbther upon their axes, producing day an~ night. It accounts tOr all the motions of
the heavenly bodies, and harmoniu. the whole system of
aature.
The C~" S,.tem is represented in Map~. ID
the centre is seen the sun, in a state or rest. Around
him, at unequal distances, are tbe planets and fixed stars,
the rormer revolving about him (rom west to east, or in
the direction of the arrows.- The white circles represent
the oriJiU, or paths, in which the planets move around
the SUD. On the right is seen a CMMt plunging down
into the system around the 8un, and then departing.
This is the Copernican Tl&eory or the 101 ar system.
M
0 how ualiJr.e the complex work. 01 man,
Heaven'. euy, artIe88, uaeDcwnber'd phAD!"
The truth of the Copernican theory is established by
the moat conclusive and satisfaotory e~idence. Eclipses
the. sun and mQOn are calculated upon this theory,
aDd astronomers are able to predict thereby their com.
mencement, duration, &c., to a minute, even hundreds
years before they occur. We shall, therefore, asBurne the 'ruth or this system, without further proor;
and proceed aocordingly to the .tudy ot the hoavenly
bodies.
or
or
Lessen
~.
)'laST GRAND DIVISIONS OF TO TINIVBBSB.
(Map 2.)
The material universe may be divided into two parts,
viz., the SOLAK SYSTBM and. the SIDEREA.L HBA VENS.
The Sol4r Sy8tem consists of the Sun and all the planet.
and comets that rp-volve around him.
The Siti8real HeaDeR. em brace all those hodiel that
•
20
PIEST GEA.lfD DITISIONS OF 1'HE UNIVERSE.
or
\
lie around and beyond the solar system, in the region
the fixed stars.
Th,e relation of the one to the other may be partially
underst~ by carefully observing Map 2.
The sun
and his attendant worlds are there seen tDithin the fixed
.tars, which occupy the corners of the map, and the
spaces without in every direction. If' the observer were
placed at a distance beyond the solar system, in any
direction, he would see vast numbers of the fixed stars
between it and him, as if they were scattered between
the eye of the learner and every part of the mnp. But
situated 88 we are, in the mi8st of the Sidereal Heft vens,
which surround us in every direction, it is not strange
that the earth should seem to be in the centre of 'the
universe.
In considering the genera:l fJubject of astronomy:, we
.ball proceed according to tbe foregoing classifica'ioD,
treatiug first of the SOLAR SYSTEM, and seCQ¥1y, of the
5mBREAL HBA.VENS.
.~ .
.
..
\
..
1
-.-.!-
PART I.
OF THE SOLAR SYSTEM.
CHAPTER 1•
.
CLASSDTCAnON or THE SOLA.R BODIES.
.fBB
S11J(, PUNBTS, PllI14A.BtIES, SECO.NDA.KIBS,
k.
(Map 2.)
Solar System d.,ives its name (rom the Latin
word Sol, the Suo. It Includes that great luminary, and
TUB
'.
all the worlds that revolve around him. To distinguish
these attendant bodies from others in the heaveDs, the,
will be denominated Solar Bodiu.
The bodies
the Solar System are divided into sey.
eral distinct classes.
I. The SUN is the fixed centre of the system, around
which all the solar bodies revolve; and from which they
receive their light and heat.
.
II. The PLA.NETS Bre those bodie. that revolve around
,the 8UD, and receive their light and beat from him. The
t term p14ttet signifies a flNl,nderer, and was applied to the.
IOlar bodies because they seemed to move or waDd~r
about among the stars.
~.
1. The planetS are divided into Prima,., and SecoiadtJ,.,
planets.
The primary planetA are those larger bodies of the
system which revolve around the SUD only, as their cen.
tre of motion. They may be distinguished on the map
by their size,. and also by tbeir being in their orbits, or OD
the white ciroles.
.
or
6
22
'~AXES AND SIGNS OF THE P.IJlARY P~NBTS.
The 8f.Condary plane" revolve not only around· the
SUD, but also around the primary planets, as· their attendants or mOODS. They: may easily be distinguished
.
on the ·map.
2. The planets are again divided into lnUrior and E~­
~rlor planets.
The interior planets are those whose orbits lie II1ithi"
tbe orbit of the earth; or between it and the SUD.
The ezt.erior ,lonets are those whose orbits lie tDithout
the orbit of the earth.
3. Five of the smaller primary planets are called.
ABteroid8. They may be seen on the map near together,
just above the SUD.
4. C~et8 are a singular class of bodies belonging to
the solar system, distinguished by their long flaunting
trains of ligbt, and also by the elongated form of their
orbits.
CHAPTER II.
OF THE PRIMARY PLANETS.
Lesson 7 •
• A.MBS AND SIGNS OF THE PRIMA.RY PLA.NBTS.
(Map 2.)
. TUB Primtlry Planets are thirteen in number.
They
are distinguished in a8tro~lomical books by certain characters or signs, which are· llsed to represent their respective
planets. The names of the planets and their symbols
are as follows:
*
· Mercury, ~
Venus,
~
Earth,
ED
Mal'll,
3
~S
l
a
Vella,
Astne&,·
JUDO,
*0
~
~
Cere.,
Pallas,
Jupiter,
SatW'D.
Herschel,
Le Verrier,
• Four new Asteroida have recently been discovered, of which,
however, very little i. known. They are called Flora, Iris, Met,.,
and Hebe.
.
•
•
•
,
K£JIBI AlfD SlSKI 0,. TIIB HOUBY PLAN.ft.
Most
or the
J(oddesees.
MBBCUBY
sign, ~, is
around it.
VBNUS
23
planets are named after heat.hen gods or
was the meuenger or the gods, and the
his CtUluceu, or roll, with ,~rptfIU twined
was tbe goddess or tOTe and beauty. Her
is a fAirrot' with a handle after the ancient
sigOt ~,
form.
The EARtH is repreaented by the sign a, denotinll a
BpAere and its equa.tur; or by $, which may denote
either meridiana of longitude, or the four quarters of the
globe. .
.
MABs wu the god of war, and hil sign, I, is a buckler
and rpefl-r •.
VESTA, the goddess 01 fire, hu the sign of an altar, I,
with a fire blazing upon it.
ASTR.&A, the name of the new asteroid, signifies a ,tar,
and may. l»e known by its appropriate sign,
JUNO was the reputed queen of heaven; and her
sign, C, is an ancient mirror, croWDed \vith a ,tar-an
emblem of beauty and power.
CERES is 80 called after the goddess of grain and har.
vests. Her sign, ~, is a ,ickle, of an antiq uated form.
PALLAS was the goddesa of Wiadom, and her sign, 9,
is tAe head of (J rpear.
J trPITER, the reputed father of the gods, is known by
the sign 2l. It was originally the letter Z, the first letter of the' Greek word Zew, the name (or Jupiter, which
has been changed in the coune of time to its preseDt
form.
SA-T11B.X was the reputed father of Vesta, Ceres, &0.
His astronomical sign, 'J, is supposed originally to have
denoted a .cytAe.
HERSCHEL, 80 called after Sir William Herschel, ita
discoverer, (also caUed Georgium Sida, or GeorKi!zn Star,
after George III. his patron, and Uranu8, (rom a heatheD
divinity,) has the sign of the letter H, with a planet suspended from the cross-4)ar-thus, '&I. It is designed to
indicate Dr. Herschel afl its discoverer.
La VBBRIEJl, the last nefD planet, sci called from its di..
*.
I
I
24
• .a.Ka A.XD .Ia•• OF TIlE
oo~erer,
PIlI.AllY PLUf.T8.
hu the sign of an L and a V' united, with a
planet suspended from the hair line of 'he V-thus, 14,·.
This al80 denotes the diacoverer of ~"e planet.·
The MOON is denoted by various signs, according as it
is new, half.grown, or full-thus, e, 1>, O.
The SUN is represented by the sign 0, deuoting an aocient Insckk,.. As the aDcients kept their bucklers brigh~
80 as to dazzle the eyes of their enemies, this iostrumeDt
was selected as the appropriate emblem of the 8UD. It is
also known by the signs t!b and
The five plan eta enclosed in braces in the" table are
the .A8teroitU.· Mercury and Venus are tbe ir&terior planets, and those outside the Earth's patb the ezIerior.
The several planets should now be looked out UPOD the
map, and' their comparative size" rlistances from the 8Uft,
and appearances carefully noticed.
MercurJ is placed close to the SUD, and directly under
him. Vemu is 8180 near the SUD, and a little above him
on the left. The EartA is next in order, above the SUD,
and a little to the right. The Moon and her orbit will be
seen near the earth. Mar8 is aD the right of the SUD, and
beyond tbe orbit of the eartb. He 'is the irst of the
nor planets. .A. bove the earth are seen the five planets
called .A,rteroida, viz.: Vt8ta, .A8trtla, Juao, Ceru, and
Pallas. Jupiter is tbe large planet below the 8UD on
the left. His surface is striped with· ourious '6el,., and he" .
is attended by (our secondary planets or moons. A bove the
Asteroids on the right is seen the beautiful planet &dum.
He is attended by Beven moon~ and 8urroundei by two ~
magnificent and wopderful ring.. Her.c1&el and his six
moons are ~1Q.ced on the left, near the upper comer of the
rnll p. Le Verrier could not be placed upon the map at his
relative distanoe, but may be imagined at twice the distance of Herschel, and of about the same magnitude.
,
e.
"Ie-
• The Board of Lo.,;tude of Parie I'8COIDIDeDd that the IMW
after the heathen pel
the lieU, with
we see no good re.,n why th" Dame
of ... discuverer should be exchanged for that of aD imuginary divinity. AstronomJ BI'eda DO additioaal appenda,.. from the MytholUQ
p1ane~ be cat.llecl Neptu"..,
the Bigll of a trident; but
01 t"~
aDcieDta.
or
..
DISTA.NCES 0. THB PUNBT8
LeS80R
Fao.
TID aUK.
t6
S.
DISTA.NCBS OF THB PLANETS FROM TRB al1K.
(Map
2.)
Map 2 shows all the planets, except Le Verrier, at their
relative distances from the sun. 'rhe scale is one hundred rn ill ions of miles to an inch. The distaDoes of &he
planets in Iniles are as follows:
Ceres"
263 millions.
Mercu."y, 37 millioo!.
V en us,
69
"
Pallas,
263
"
Earth,· 95
"
Jupiter,
495
"
Mars,· 145
"
SatuFn,
900
"
Vesta, 225
"
Herschel, 1,800
"
Astrrea, ~53
"
Le Verrier, 2,800
"
JUDO,
254
"
It is difficult to conceive justly of these vast distances.
Were a body to move at the rate of five hundred mile.
an hour, without intermiSliioD, it would require near eight
and a hal f years for it to pass from the sun to the nearest
of these planets. To visit the flarth would require over
twenty-oue years; and to reaoh Herschel over four hUDdred years!
.
Railroad oars travel at the rate of- about thirty miles
an hour. or a mile in two minutes. Now if there was a
railroad froln the sun to the orbit of Le Verrier and the
orbits ~ the other planets were stopping-places 00 the
route, the train would reach
'
Meroury, in
152 yea ....
V en U8,
"
264
"
. Earth,
"381
"
Mars,
"554"
Jupiter,
"1,884
"
Saturn,
"3,493
"
Herschel, "6,033
"
La Verrier, u 13,700
"
Such a journey would be equal to riding 900,000 tim.
a
26
DEGRBBS, MINUTES, A.ND SECONDS BXPLAINlbI.
over Whitney's proposed railroad from Boston to Oregone
It is now about 5,850 years since the creation of the
world. Had a train of cars started from the sun at that
time to visit the orbit of Herschel, and travelled day and
night ever since, at the rate of thirty miles per hour, they
would still have 284 millions of miles to travel before
they could reach their journey's end. To finish the passage would require 1,083 years longer; the whole of
time past and a thousand years to come! To reach the
distant orbit of ~e Verrier the train would need to proceed onward, at the same rapid rate, nearly 7,000 years
longer!
Such is the vast area embraced within the orbits of the
planets; and the spaoes over which the sunlight travels,
to warm and enlighten its attendant worlds.
Lesson 9.
I)BGIlDS, IttJNUTBS, AND SECONDS EXPLA.INBD.
(Map 3.) .
..
In astronomy, the distances and magnitude of bo~iel
are often given in degrees, minute., and ,eeCJ'lUl8. It will
be necessary, therefore, to show what these mean. ~,.'t
"A circl.e is a plane figu1'~, comprehended by. single
curve line, oalled its circumference, every part o£ *tWhich .
is equally distant from the point within called its .eeht'.:e."
A ci rcle is represented on the right at Fig. 1.
.
A q,/,adrant is the fourth part of a cirole.
A sextant is the sixth part of a circle.
A Bign is the twelfth part of a circle.
A degree is the thirtieth part of a. sign, or"one three
hundred and sixtieth part of a circle.
·
A minute is a sixtieth part of a degree; and
. A ,eeond. is the sixtieth part of a minute.
On the map the circle is divided off into parts of ten
degrees each, and numbered in figures every thirty· degrees, or oftener. It· will be seen that one.fourth of a
•
•
·1
.A.KGULAJl DISTANCES, KAGNITUD• ., BTC.
27
lit"',
oil ~le contains just tAree riga, or aitlet, tlep. . ; and
half a oircle U 1igM, or mAe AUflued, and
tkgrea.
All oircles, whether great or small, have the same
Dumber of degrees, namely, tJiree hundred and sixty.
But one hundred BDd eighty marks the greatest possible
angle, as a pair of compasses can be opened DO farther
than to bring the legs in a straight line. These degrees,
&0-., are used to represent the angle which any two linM
form, coming from different points, and meeting at the
eye in the centre.
In the figure the lines passing from the stars on the
left to the eye, are found by the measurement OD the
oircle to be ten degrees apart. If the dotted liDe was
perpendicular to the lower or plain one, they would be
ninety degrees apart, &0.
Degrees, minutes, and seconds are denoted by certain
characters, as follows: 0 denotes degrees, ' denotes minutes, and" denotes seconds. Thus, 100 15' 20" is read
ten degrees, fifteen' minutes, 8Dd twenty seoonds.
Measurement by degrees, minutes, and seconds, i8
called .Angular MetUUrement.
Lesson 10.
AKGULA. DISTA.NCBS, MA.GNITUDES,
&0.
(Map 3.)
In
Fig. 1, the observer is represented 8S seeing two
stars on the left side of the map. By looking at the
graduated or divided cirole, it will be seen that the angle
which these two stars make at the eye is 1Oc:>. The stara
are therefore said ..0 be 100 apart. If a globe filled the
same angle, or number of degrees, as shown on the map,
we should say it was 100 in diameter. If the_~pace be.
tween the foot of a mountain and its top -filled the same
angle,' we should say it was 100 high;' and if a comet
passed through the same -angle in one hour, we should
8ay its velocity was 100 an hour.
All circles, whether large' or small, have the sameDumber of degrees j but the angle which an object makea
28
THE Stnf AS SBBN PROM THB DIFPERBNT PLANETS.
at the eye will be great or small, according as it is Dear
to or di:ltant from the observer. This is illustrated by
Fig. 2. On the left is the object. To the observer in
the centre the globe is 200 in diameter; but to the one
on the right its diameter is but 10°. To a third observer,
at twice the distance of the last, it would appear but 5°
in diameter, &0. This sho~8 why objects, grow smaller
in appearance as we recede from them, and large.r as we
advance towards them. Their apparent magnitude is in.
creased or diminished in proportion to the distance frtmj
.ldeA they are "ielDea.
Lesson 11.
THB SUN A.S SBEN FROM THB DIFFBRENT PLA.NETS.
(Map 3.)
By the' table of distances, (8,) and also by Map 2, it
will be seen that the Sun is about twice as near to Mer.
cu ry as he is to Venus. Of c'Jurse, then, according to
the principle illustrated in Fig. 2, his apparent diameter
must be twice as great when viewed from Mercury as
. when viewed from Venus. From the Earth it is still
Rmaller, and so on till we view him from the distant orbit
or Le Verrier, from which he would appear but a small
glimmering point in the heavens. Ftom the fixed star
Sirius, he would" appear smaller than Sirius appears
to us.
The relative apparent magni'tude oC the' Sun, as seen
Crom the ditfeI:ent planets, is represented by Fig. 3. His
angular diameter would be,
From Mercury • •
"
"
"
.,"
II
/,
Venus
Earth
Mars '"
Velta
Astrma
Juno •
S!f
• • • 4
• • • 32'
• • 21'
'
. . . lSi'
• • • 12'
- - • 12'
· lit'
From Ceres.
- 11 '
" Pallas
...
Jupiter
6'
"
"u Saturn . . .
Herschel.
" Le Verrier • 50"
~:
•
PHILOSOPHY OF THB DIFFUSION OP LIGHT.
29
From Mercury it is supposed that the spots OD the SUD
would be visible to the naked eye, as seen on the map j
and from Le Verrier the Sun himself wquld appear but as
a large and brilliant stl1r. Let the student imagine him.
self as approaching the SUD till it has four times its present apparent diameter, and his spots stand out in full view
to the naked eye; and then let bim recede from the sun,
pass the earth and the orbits of Jupiter and Saturn, and
retire away into space, till the SUD appears but a glim.
mering star, aod he will have lOme raint conception of
the almost inconceivable. distances of the 801ar bodies.
Lesson
I".
PHILOSOPHY OP THB DIFFUSION OP LIGHT.
(Map
3.)
Light always !Doves in straight lines, unless turned out
of its course by reflection or refraction. This is repr~.
sented by Fig. 4 on the map; where the light is seen
passing to the right, from the SUD on the left. From this
law it follows that the squares A B and C in the diagram
• wou Id receive equal quantities of light; but as B has
four times, and C nine times the surface of A, a single
square of B equal to A,- would receive only one.fourth
as much light as A; and a square of C, equal to A,
would receive only one.ninth as muoh. This difference
in the amount of light received is caused by the unequaJ
di8f.ance8 of the several squares from .the miniature sun
on the left. The distances are marked on the upper line
of light by the figures 1, 2, 8.
The rule for determining the relative amount of light
reoeived by several bodies, respectively, placed at llD6(lUlll
distances from their luminary, is, that their light i8 'flfJer8ely Q,8 the aq'llare8 of their diatancu. This rule, al80,
is illustrated by the figure. The sq ua~e of 1 is 1; the
square of 2 is 4; and the square of 3 is . 9. Hence 1., f,
and 1-, will represent their relative light, as already
.hown. The checks are designed to illustrate this. .ole.
a*
•
30
LIGHT A.ND HEA.T OP THB SEVERAL PLANBTS.
Lesson "13.
LIGHT AND BEAT OF THE SEVERAl. PLANETS.
(Map 3.)
By applying the foregoing rule to the planet8, at their
nlapecti va distances from the SUD, we are enabled to 8.Hcertain the relative amount of light received by each;
and on the supposition that their heat is proportionate to
their light, we can easily determine their a"erage tem.
perature. At the bottom of the map the planets are
placed at their relative distances from the SUD, QOmmeocing with Mercury on the left, and extending to Herschel
on the right. Immediately over each planet respectively,
and near the upper line of the diagram, is marked the
proportionate light and heat of each, the earth being one.
They are as follows:
6t
Mercury. • - • - V en us - - - - • - • 2
Earth - - • • - - - 1
Mars. - - - - - - Vesta - - • • • - Astnea • - - - - •
t
t
1 uno· - • • - - • Ceres and Pallas. - I
. 1 upiter - • - - - - -1Y
Saturn • - - - • - -h
Herschel • - - • 111
Le Verrier - - • rho .
It appears, therefore, that Mercury bas 6! tim~s as
much light and heat as our globe; Herschel only
and Le Verrier only...-Jn.nth part as much. Now' if the
average temperature
ilie earth is 50 degrees, the average temperature of'Mercury would be 325 degrees; and
as water boils at 212, the temperature of Mercury Inust
be 113 degrees above that of boiling water. Venus
would have an average temperature
100 degrees,
whioh would be twice that of the earth. On the other
hand, Jupiter, Saturn, Herschel, and Le Verrier, seem
doomed to the rigors of perpetual winter. Think of a
region 90, 368, or 1300 times colder than the average
temperature of our globe I
m,
or
or
I
XA.GNIT17DB OF THB PLANBTS.
II
31
Who there iDhabit must haYe other powen,
Juices, and vew, aDd 1eD88, aDd life, thaD OUN:
Oue momont'. cold, like thein, woold pierce the beme,
Freeze the heart'. blood, aDd tura u all to Itou.e !"
It is not certain, however, that the heat is proportionate
to the light received by the respective planets, as variou
local causes may conspire to modify either extreme of
the high or low temperatures. For instance, Mereu".
may have an atmosphere that arres~ the light, and screeD.
the body of the planet from the in8upportable rays of the
SUD; while the atmospheres of Saturn, Herschel, &0.,
may act as a refracting medium to gather the light (or a
great distance around them, and concentrate it upon their
otberwise cold and dark bosoms. .
Lesson 14.
JUGKITUDB 0,. THE PLAlfBTS.
(Map 2.)
On the la~ge map the planets are drawn upon a seale of
4:0,000 miles of diameter to an inch. The Sun is represented as but a point, because he could not be placed in
the map, of a size proportionate to the planets.
The diameters of the several plane~ are as follows:
Mercury, 3,000 miles.
Venus,
7 2800 "
Earth,
8,000"
Mars,
4,200"
Vesta,
270 u
Astrrea, unknown. .
Juno,
1,400"
Ceres,
Pallas,
Jupiter;
Saturn,
Herschel,
Le Verrier,
1,600 miles.
2,100"
89,000"
79,000"
35,000 "
35,000 "
By carefully obse"ing each planet as laid down on
the map, it will be seen' that their relative magnitudee
correspond with their relative diameter. as bere stated.
,
•
32
aBLATIVE XAGNITUDB OP THB SUN AND PLANBTI.
Lesson 13.
1lBLATIVB MAGNITUDE OF THE SUN AND PLA NE;TI.
(Map 4.)
The relative magnitude of the sun and planets E repre:sented in Map 4, Fig. 1. The scale of the charts is the
same as in No. ~-Damely, 40,000 miles of diameter to
an inch. As the sun is 886,000 miles in diameter, he
is drawn 221 inches across, to show his true magnitude
as compared with the planets. These may be seen on
the right side of the m~p, commencing with Mercury at
the t01>, and passing downward to Herschel. La Verrier
is opposite Herschel on the left.
Thp. seeondary planets will be seen around their primaries.
.
The magnitudes of the primary planets as compared
with the earth, are as follows, viz. :
n
Mercury, • • - Venus, • - - - • Ii
Earth,. • •.• -. 1
Mars, - • • • ••
Vesta,. - - _. i I 0 0 0
Astrlea, unknown.
Juno, - • • - - • rh .
t
(Jeres, • - - •
.Pallas, • - • Jupiter, - ••
Saturn, •• Herschel, _.
• 11t.
• -h
1,400
1,000
Le Verrier, -
90
90
The BUft is 1,400,000 times larger than the earth, and
500 times larger than all the other bodies of the Solar
System put together. It would take one hundred and
twelve such globes as our earth, if laid side by side, to
reach across his vast diameter.
The moon's orbit is two hundred and lorty thousand
miles from the earth. N o~, if the sun was placed where
the earth is, he would fill all the orbit of the mOOD, and
extend more than two hundred thousand miles beyond it
on every side! What is a globe like ours compared with
luch a vast and ponderous body as the SUD'
~
"
"
l
eOllP~.~TIT. DBNIITY 01' TD PLANETS.
33
Lesson 16.
COlllPAKA.TIVB DENSITY OP TBB PItANETI.
8y deMity is meant compacme.8 or clolene8•. of ptJ,:,..
Hence we say cork is less dense than iron, and Itone ia
more dense than common earth. In like manner the
plane~s differ from each other in density, or in the compaotn~8S of the substanoes of which they are composed.
The comparative density of the I8veral planets, and tbe
eubstances with which they most nearly agree in weight,
will be shown by the following table, in which the earth
fa taked as the standard of camparilOn.
Mercury, •• 3-lead.
Venu&, • • • 1'. earth.
Earth, ••• 1
Mars, ••• h--earth.
Jupiter,
Satum, •••
Herschel, •
La Verrier,.
Sun, • • • •
,Jo-cork.
l~water.
unknown.
l-water.
•• i-water.
This table is one of cODsiderable importanoe, and
.uld be com~itted to mem~ry. Ita uses will be more
clearly see.n in the ~ext lesson.
,
Lesson 17.'
MrTJlA.CTION OP TBB PLAKBTS.
Attraction or gravitation is the ten.denoy of bodies to1Fards each o~.~¥r, \ By this i?Buence sub~tances fall to
. the earth, wb@n raIsed from It and left WIthout. support.
The force of 'attraction is what constitutes the !Deig"t ot
Ilodies; and its amount depends upon the q u&ntity of
matter in the bodies attracting, and their distances from
each other.
.
From the above law of attraction it follows that large
bodies attract much inore strongly than small ones, pro..
Tided their densities are equal, and their distances the
same; and 88 the force of attraction coDstitutes the we;''''
.'
I
34
ATTUCTION O:r THB PLANBTS.
of a body, it follows that a body weighing a given number
or pounds on the Earth would weigh much more on J u. piter or Saturn;, and much less on Mercury or the Asteroids.
The following table shows the relative attractive force .
of the Sun and Planets. A body weighing one pound 00
the Earth, would weigh
•
On Mercury,
"
"
"
"
"
"
"
Venus, •
Mars,
Jupiter, •
Satum, •
Herschel,
Le Verrier,
The Sun,
•
•
lb..
os.
0
0
0
9}
15
2
•
•
•
•
•
•
8
8
1o 125t
unknown.
28
5)
A· person weighing 150 lbs. on the Earth, would con..
sequently weigh 375 Ibs. on Jupiter; 4,250 lbs .. on the
SUD_; and ol1ly 75 Ibs. on Mars. The attractive force or
the Asteroids is 80 slight that if a man of ordinary muscular strength were transported to one of them, he might
probably lift a hogshead of lead from its surface without
difficulty.
But the learner will notice that the attractive force, as
shown in the above table, is not in strict proportion to the
bulk of the planets respectively. This difference will be
accounted for by again referring to Lesson 16, where the
subject of deMit, is considered. From the principles
there laid down, it will be seen at once that though one
planet be as large again as another, still, if it were but
half as den~e, it would contain no more matter than the
smaller one; and their attractive force would be equal.If' Jupiter, for instance, were as dense as the earth, his
attractive force would be four times what it now is; and
if the density or all the· solar bodies 'Yas precisely the
same, their attractive force, or the weight of bodies on
their surfaces, would be in exact proportion to their
bulk.
. . .IODle UTOL11'l'IOKI 01' 'I'D PL.lKftB.
3ti
Lesson 18.
'BllIODIC eVOLUTIONS o:r THB PL.llfa'S.
(Map 2.)
It has already been stated (3, 4, and 6) that the planet.
revolve around the sun. Their direction is from welt to
east, or towards that part of the heavens in which the SUD
rises. The passage of a planet from any particular point
in its orbit, around to the same point again, is called it.
periodic ref'olution; and the time occupied in making suoh
revolution is called its ptriodic time.
The periodic times of the planets are 88 follows:
Mercury, •
Venus,
•
Earth,
•
Mara,
•
Vesta,
•
Astnea,
•
Juno,
•
Ceres,
•
Palla.,
•
Jupiter,
Saturn,
Herschel, •
Le Verrier,
•
•
0
•
•
•
•
•
1
1
'"
8
4:
4:
4:
4:
•
•
•
•
•
•
•
•
•
o years,
•
•
• . 11
• 29
•
84
• 164
"
"
"
"
"
"
"
88 days
225
822
230
51
131
"
"
"
"
"
222 "
"cc·
" 222
317
" 175
"
"
"
"
"
The periodic tio18 of a planet may very properly be
oalled its ,ear; hence, one of Herschel's years would
equal 84 of ours; a year of Saturn is equ\ to about 30
of ours, &0.
But this differenoe in the length of the years or the
aeveral planets, is not owing .solely to the difference in
the extent of their orbits: there is an aotual difference in
their velocities, 88 will be Ihown in the next 1818OD.
a6
CBNTKIPBTAL AND CBNTRIFUGAL FORca.
Lesson 19•
. HOURLY MOTION OF THB PLANBTS IN THBIR ORBITS.
,
(Map 2.)
Mercury,.
• 96,000 miles.
Venus, •
• 75,000 "
Earth,
•
- 68,000 "
Mars, •
55,000 "
Ve8ta,
•
- 44,000 "
Astnea,..
• 42,000 "
Juno,
••
• 42,000 "
Ceres,..
41,000 "
Pallas,..
41,000 "
Jupiter, • • 30,000 "
Saturn,
• • • 22,000 "
Herschel,
•
15,000"
Le Verrier,.
•
• 11,000 "
Here, instead of finding the swiftest planets perform.
ing the longest periodic journeys, this order is reve rsed,
. and they are found revolving in the smallest orbits. The
Dearer a planet is to the SUD, the more rapid its motioll,
ud the shorter'its periodic time. The reasons for thia
dift"erence in the velocities and periodic times of the planeu, will appear i~ the next lesson.
it
Lesson
~O.
CBNTRIPBTAL AND CENTalFUGAL poaCBS.
(Map 2.)
The tendency of the planets towards the sun, or in
other words, the mutual attractive force of the sun and
planets, is called the centripetal force; aqd the projectile
-force, or that which impels the planets cfnward in their
. orbits, is called the centrifugal Coree. If the centripetal,
or Coroe of attraction, was suspended, the planets would
DIURNAL Jl&VOLl1TIONS 0., TUB PLANBTS.
37
lIy off in straight. lines beyoDd their present orbits, and
leave .the Solar System forever; and if the centrifugal
force was suspended, the planets would yield to the oeDtripetal force, and fall to the surface of the sun.
It has already been stated, in Lesson 17, that the
force of attraction depended somewhat upon the distance8
of the attracting bodies; those nearest together being mutually attracted most. It follows, therefore, that ~Iercury
has the strongest tendency towards the sun, Ven us next,
the Earth next, &0., till we get through to Le Verrier;
and as the centrifugal force, which is to balance the centripetal, is created by the velocity or projectile force
the planets, that velocity must needs be in proportion to
their distances respectively, from the sun; the nearest
revol ving the most rapidly. This we find to be the actual
state of things in the Solar System. And what wisdorD
and skil.l are displayed in so adjusting these great forces,.
as that the planets neither fall to the sun 00 the one hand,
Dor fly off beyond the reach of his beams on the Mher! AI
it is, they remain balanced tn their orbits; and steadily
revol ve at stated periods from age to age. "0 Lord, how
manifold are thy works! in wisdom hast thou made them
or
all."
.
Lesson
~1.
DIl11I.NAL REVOLUTIONS OF THE PLANBTS.
(Map 8.)
In addition to the motion of the planets in their orbit.
tiround the sun, they have another motion around their
respective axes, producing the vicissitudes of day and
night. So far as is known, the time of these revolution.,
or the length of their days, respectively, is as follows:
24 hours.
Mercury, • • • •
Venus,
• • • • • 231 "
Earth, • • • • • • 24
"
Mars, • • • • • • 24! "
Jupiter,
• • • • • 10
"
Satum,. • • • • •
4:
101 "
38
•
{
TRUE -PIGl1JlB OF THE PLANETS.
Hersche1, • • •
•• u,nknown.
Le Verrier, • • • • unknown.
Sun,
• • • • 25 days 14 hours.
The learner will not fail to observe the striking simi.
larity in the length of the days of the first four of the
planets; much less the very rapid motion of Jupiter and
Saturn upon their respective axes. As their days are
only about five hours long, the, sun must seem to mount
very rapidly up their heavens, and to decline as rapidly
downward to their western horizon. His progress must
be apparent to the inhabitants of those planets.
From the rapid, rotation of Jupiter and Saturn, it follows that they must have about 875 of their days in" one
of our years; and as Jupiter's year is about 12 times,
and Saturn's about 30 times as long as ours, it follow&
that the former will have about 10,500 days in his year..
. and the latter about 26,200.
'
The fact that the planets revolve upon their respective
axes is ascertained by observing the motion and direction
of spots on their snrfaces; or, in other words, their CORtinents and seas. For instance, in observing the sun, we
discover one of his spots on his eastern limb or edge, and
by watching it, find t~at it passes over his disc and disappears from his western limb in about 12 days and 19·
hours. From this we infer that it would pass around and
reappear "!here it was first seen, in 12 days and 19 hours
longer; making the time of the entire revolution 25 days
and 14 hours. It is in this way that the time of the revolution of the planets upon their axes is determined.
The effect of the rotation of the planets in modifying their
forms, will be shown in the next lesson.
Lesson. ~~.
TRUE FIGURE OF THE PLANETS.
The spherical form of the planets evinces the supreme
wis!iom of the great Creator. Were they cubes, (or in.
stance, instead of spheres,- their temperature would be Car
•
-,
THB BeLInI'"
39
Jess regular than it DOW is; the 8un would rise suddenly
upon a whole side at once, and as suddenly disappear at
night; and the blessings of twilight, and the gradualsuc.
cession of day and night, as they DOW transpire, would be
unknown.
On the' maps the planE!tS are represented as exactly
round, ~r spherical; but this is not their precise form.
Their rapid motion around their respective axes has a
tendency to depress or flatten them at their poles; and
extend or widen them at their equators. Hence their
equatorial diameter is considerably greater than their polar diameter; the true figures of the planets being that
()f
oblate Bpheroida.
The difference between the polar and equatorial diam •.
. eter of the planets respectively, so far as known, is as
follows:
.
. Earth, • • 36 miles. Jupiter, • • 6,000 mile••
Mars, • •
25"
Saturn,.. 7.500. "
Lesson
~3.
THB ECLIPTIC.
(Map 5.)
The Ecliptic is the plane or level of the earth's orbit,
indefinitely extended. Fig. 1 represents the earth in her
orbit, as she would appear to a beholder placed at a dis.
tance, and elevated above the plane of the ecliptic. She
is represented in perspective as appearing smaller as shQ
grows more distant-as keeping her poles tow~rds the
same points in the heavens; and as exhibiting the phases
of the moon according as we- see more or less of her en.
lightened side. She is colored green, as she \lsually is
through the series, to represent ne~ vegetation. The arro.ws placed in har orbit show her direction.
If the student has any difficulty in getting a rQrreot
idea respecting the ecliptic, let him SUppofie the orbit of
th.e earth to be a hoop of small wire laid ~pon a 8Bble:
t.he surface of the table, both within and without the hoop,
would then represent the plane of the ecliptic.
40
OBLIQUITY OF TBB BCLIPTIC.
From the above definition and description, it will be
leen that the ecliptic posses through the centre of the
earth, and the centre of the sun; conseq uentl y the ecliptic and the appar~nt path of the sun through the heaveDs
are in the same plane. It will be ea.sy, therefore, to ascenain the true position of the ecliptic in the heavens;
and to imagine its course among the stars on the other
lide of the globe.
l
Lesson
~4:.
THE POLES OF THE ECLIPTIO.
(Map 6.)
,
The poles or the earth are the extremities of her axis.
The poles of the ecliptic are the extremities of the im..
aginary axis upon which the ecliptic seems to revolve.
The ends of a rod or pointer, run through the. map
at the centre of the SUD, would exactly represent the
poles of the ecliptio.
As the ecliptic and equator are not in the same plane,
their poles do not coincide, or are not in the lame points
in the heaveDS.
Lesson
~3.
OBLIQUITY OF THB BCLIPTIC.
(Map 8.)
It has already been stated that the sun as well as the
earth is always in the pIllne of the ecliptic. But he
is north o( the equator for six months, and south six
months. It follows, therefore, that one.. half the ecliptic is
south of the plane of the earth's equator, and the other
half north of it.
As the axi~of the earth is inclined to the ecliptic 23°
28', her equator must make the same angle to the ecliptic in the opposite direction; and the ecliptic must erosa
the plane of the equator obliquely. The angle or 230
.
THE ZODIAC-SIGNS, BTC •
41
2R' thus made is what constitutes the obliquity of the
8cliptic~
This subject will be better understood by examining
the ,figure of the earth, and the position of her equator, as
represented on the map.
Lesson
~6.
TBB ZODIAC.
(Map 6.)
The Zodiat: is an imaginary belt 160 wide, namely.
80 on each side of the ecliptic; and extending from west
to east quite around the heavens. It is represented on
the map by the plain circles above and below the ecliptic. In the heavens the Zodiac includes the sun's apparent path, and a space of eight degrees south and eight
degrees north of it.
Lesson
~7.
SIGNS OP THE ZODIA.C.
(Map 5.)
The great circle of the Zodiac is divided into twelve
equal parts called 8igna. These divisions are shown on
the map by the spaces between the perpendicular lines
that cross the Zodiac. The ancients imagined the stars
of each sign to represent sbme animal or object, and gave
them names acoordingly.
.
The names, order, and symbols of the twelve signa
of the Zodiac, are as follows:
Ariel, or the Ram, •
TatU'U8, the Bull, •
Gemini, the Twinl,.
Cancer, tbe Crab, •
Leo, the [Aon, • •
Virgo, the Virgin, •
."
Libra, the Balance, '.
• ~
• II
•§
• ~
• 1tR
,.
.6
Scorpio, the Scorpion, • 111.
Sagittarius, the Archer, t
Capricomus, the Goat, • ~
Aquarius. the Waterman,
Pisces, the Fishea, • •
=
*
The anoient Astrologists supposed that each of the81
42
NODES-A.SCBNDING AND DESCENDING.
signs governed some partioular part of the human body;
and even in modern times people sometimes consult the
frontispiece of their almanacs, to see whether the" sign"
is "in the head," or "in the heart;" 80 as to attend to
certain important atr~irs "when the sign is right."
The idea seems to be that the word "aign" signifies an
omen or prognostication; and that the signs of the Zodiac
have some mysterious control o,·er the destiny of man.
But this fragment of heathen ~trology is fast falhng into
disrepute; and it is hoped will sooo be utterly banished
from every civilized country.
Lesson
~S.
NODES-A.SCENDING AND DBSCENDING.
~:
(Map 5.)
"a"
II
~".
.:~
I
Fig. 1 represents an interior planet as revolving':~D
an orbit inclined to the ecliptic at an angle of about 4~ ;
and as both planets revol ve around the same centre of at.
traction, the interior planet must pasl:I through the plane
of the ecliptic twice at every revol ution: once in ascend.
ing, and once in descending. These two points, where
the orbit of a planet passes through or cuts the plane of
the ecliptic, are called the node. of its orbit. One is
called the ascending, and the other the descending node.
On the map A. N. is the ascending node, and D. N. the
descending node. They are also denoted by the follow.
ing characters, viz.: g for the ascending, and U for the
descending.
A line drawn from one node to the other is called the
line of the node., and may be seen on the map, marked
L. N.
. In the figure the ascending node is represented as
being in the middle of Libra, and the descending in the
middle of Taurus. The design is merely to illustrate the
IU bject, without representing the actual line of the DOOea
of anyone of the planets.
TIlAK81T8.
Lesson
43
~9.
T1lA.NSITS.
(Map 5.)
By consulting Fig. 1 it will be seen that if an interior
planet 'vas at her ascending node, and the earth on the
line of the nodes, on the same side or the ecli ptic, the
planet would seem to pass over the body of the sun, 88
shown in the figure. This passage of a planet over the
sun's disc, or between the earth and the SUD, is called a
Transit.
Mercury and Venus are the only planets that can make
a transit visible to US; as all the rest are exterior to the
earth's orbit, and consequently can never come betweea
the earth and the sun. But the earth. may make transits
visible from Mars, the Asteroids, and Jupiter; and they
in turn may make transits for the inhabitants of all exte.
rior worlds. The principle is, that each interior planet
may make transits for all tbose that are exterior.
But transits can never occur except when the interior
planet and the earth, or planet from which the transit is
seen, are both on tbe line of the nodes. The sun and
both the planets will then be in a line, and the one near·
est the sun will seem to pass, like a dark round spot, over
the sun's face.
- ,
.
If the orbits of Mercury and Venus lay in the plane
of the ecliptic, (see Lesson ~S,) they would make transits
,rhenever they were in conjunction with the sun. Even
with their present inclination the same phenomenon would
take place twice in every revolution, if Venus and the
earth, for instance, were' to start together from the line
of Venus's n<?des, and revol ve in the same periodic time.
Venus would then al ways make a transit in passing her
nodes.
To calculate transits at anyone node, we have only
to find what number of revolutions of the interior planet
are exactly equal to one, or any number of revolutiolll
.1
44
TJl.A.NSITS OF M.RCURY.
the earth; or in other
planet will again meet on
In the case of Mercury
865.256; from which we
O(
7 periodieal l8YoiutioD8
13"
"
33"
"
46"
"
words, when the earth and the
the line of the planet's nodes.
this ratio is as 87.969 is to
ascertain that
of the Earth are equal to 29 of Mercury; .
"
"
"
54
u
,.
"
"
137
II
"
"
"
191
"
Therefore transits of Mercury, at the lame node, may
happen at intervals C!f 7, 13, 33, 46, &c., years.
All transits and eclipses are calculated upon these
. princi pIes.
Lesson 30.
TRANSITS OF MERCURY.
(Map 5.)
The following is a list of all the transits of Mercury
(rom the time the first was observed, Novembe~6, 1631,
to the end of the present century.
l63l-November 6.
1776-November 2.
1644-November 6.
1782-November 12.
1651-November 2.
1786-May 3.
I 789-November 5.
1661-May 3.
1664-November 4.
1799-May 7.
1674-May 6.
1802-November 8.
18IS-November II.
I 677-November 7.
1 ~22-November 4.
1690-November 9.
1697-November 2.
1832-May 5.
1707-May 5.
1835-November 7.
171 O-N ovember 6~
1845-May 8.
1723-November 9.
1848-November 9.
1861-November II.
1736-November 10.
I 86S-November. 4:.
1740-November 2.
1743-November 4:.
1878-May 6.
l753-May 5.
1881-November 7.
1756-November 6.
1891-May 9.
1769-November 9.
1894-November 10.
ftAlfSITS OF VBWI.
46
\
By c are fu}] y examining the foregoing table it will be
leen that the transits of Mercury all occur in the months
of May and November. The reason for this is, that hi.
ascending node is in the 16th degree of Taurus, and bis
descending in the 16th degree of Scorpio; the first
which points the earth always pa88es in November, and
the other in May.
All the traosits, therefore, that happen in November,
are when Mercury is at his ascending node, and the residue are w,hen he is at his descending node.
Again: If we take the transits in their order, as laid
down in the table, they will be found not to occur at intervalR of 7, 13, 33, 46, &c. years, as previously stated ;
but if we take those only th~t occur at the .arne node, we
shall find them regulated according to the ratio prescribed.
For example: from 1631 to 164+ is 13 years; from
1644 to 1651 is 7 years; from 1651 to 1664 is 13 yeara;
from 1664 to 1677 is 13 years; from 1677 to 1690 is 13
years; from 1690 to 1697 is 7 years, &0. Thus far
their intervals are 7 and 13 years; but they may bappen
at the other periods.
If we take those occurring in May we shall find them
conforming to the same ratio; as previously laid down
in Lesson 29.
or
Lesson 31.
TRANSITS OF VENUI.
(Map 5.)
8 periodical l8yoluticma or the Earth are equal to 13 of Vea. .
135
u
"
""
"382"
243"
"
""
"346"
'251"
.e
""
"408"
291"
"
.."
"475"
The line of V enus's nodes lies in the middle of Gemini
and Sagittarius; which points are passed by the Earth
io December and June. It follows, therefore, that transits
of Venus must always happen in one or the odler of these
months.
~
46
INCLINA.TION OF THB ORBITS 01' TIIB PLANBTS.
I
The following is a list of all the transits of Venus
(fom 1639 (the time the first was observed) to A.. D. 2012~
1639-December 4.
1874-December 8.
1761-Juoe 5.
1882-December o.
1769-1 une 3.
2004-J une 7.
1822-December 6.
2012-Juoe o..
Here it will be· noticed, that the transits for December
occur at interv.als of 235 and 8 years; and those of June
at intervals of 8, 235, and 8 years, according to the ratio
previously stated.
Lesson
3~.
INCLINATION OP THE ORBITS OF THE PLANBTS TO THB
PLANE OF THE ECLIPTIC •
. (Map 5.)
,
Fig. 1 represents the orbit of. a planet. as inclined to
the ecliptic at an angle of about 45 0 • But none of. the
planets ha ve 80 great an inclination; the main object
here being to illustrate the subject of nodes.
The inclination of the orbits of the several ,planets
to the plane of the ecliptic, is shown in Fig. 2. In the
centre is seen the sun. The dotted line running hori.
zontally across the map, and through the sun~s centre,
represents the plane of the ecliptic. On the right and
left are seen arcs of a circle, divided off, and numbered
every ten degrees. The plain lines, ·inclined more or
less, and passing through the centre of the sun, repre.
sent the plane of the orbits of the planets respectively.
Un the left, outside the graduated circle, are seen the
Dames of the planets; and just witJtin the circle the
amount of the inclination of their orbits. This inclination is as follows : Mercury. • • • 7 0 Ceres • • • • • 10 0
Venus • • • • 31 Pallas • • • • . 34
Earth
••••
Jupiter. • • • • I
2
Mars • • • • •
Saturn. • • • • 2
Vesta. • • • • 7
Herschel • • · •
4
Astrma • • •
Le Verrier, not determined.
Juno • • • • • 18
I
· 71
l
CBLBSTIAL LATITUDB AND LONGITUDE.
47
The wide colored portion of the graduated circle showl
the limits or the Zodiac, extending 80 on each side or the
ecliptic.
It will be seen that the orbits of most of the planets lie
within the limits of the Zodiac; but Juno, Ceres, and
Pallas extend beyond its bounds. They are therefore
sometimes called the ultra zodiacal planets. The orbit
of La Verrier is not inserted in the map.
N ear the middle of Fig. 2 are seen two come" in their
orbits; one coming down from the heights North or the
ecliptic, passing around the sun and then reascending;
and the other coming up from the depths South or the
ecliptic. The design is to illustrate the fact that the
comets do not revolve in the plane of the ecliptic, or as
nearly so as do the planets; but that they approach the
sun from all directions, or from every point in the heavens.
Lesson 33.
CBLESTIAL LATITUDB.
It will be understood by LessQn 25; that the ecliptic
and equinoctial are two different planes,. intercepting each
other at an angle or 23,0. Now, although terrestrial
latitude is distance north or south of the earth's equator,
yet celestial latitude is not reckoned from the celestial
equator, or equinoctial, but from the ecliptic. Celestial
latitude is, therefore, distance 'I&Orth or Bouth of the ecliptic;
and as one half of the ecliptic is ,outh of the earth'8 eq 00·
tor, (Lesson 25,) it follows that a star may be in
celestial latitude, which is, nevertheless, ,outA of tAB 6lJUl,·
nor'"
noctial.
Lesson 34.
CELESTIAL LONGITUDB.
(Map 6.)
Longitude on the earth is distance east or weat (rom
any given point. qn all English charts and globes it i.
.11
48
LONGITUDB OP PLANETS' ASCBNDING NODBS.
reckoned from Greenwich Observatory, near London; but
on those of American origin it is usually reckoned from
the meridian of Washington City.
Longitude in the heavens is reckoned from the vernal
eq uinox, or the first degree of Aries, eastward, around the
eclipt'lc to the same point again. The map is a vertical
view of the Zodiac, and when suspended to the south or
the learner, gives a pretty correct idea of its poHition in
the hea veDS.
Beginning at the first degree of the sign Aries, and
passing eastward around the ecliptic, the longitude is
marked off in degrees on the map, and numbered every
ten degrees. The entire circle, like all other circles,
consist.s of 360 degrees; which bring us to the point from
which we started.
From what has been said, it will be obvious that if the
sign Aries, for instance, were directly overhead, or on
the meridian at any given time, Libra would be in the
oppos~te part of the Zodiac, or in the heavens beyond the
other side of the earth. In using longitude to describe
the position of stars or other objects in the Zodiac, we
should say the Twins were between the 70th and 80th
degrees; the Lion between 130 and 140; the Balance
between 190 and 200; the Goat between 280 and 290,
&c. The student can traoe them out for himself; and
mark their longitude.
.
Lesson 33.
LONGITUDE OP THE ASCENDING NODES OP THE PLANETS.
(Maps 5 and 6.)
On Map 5, Fig. 1, the line of the nodeR of the interior planet enters the middle of A ries, and the middle
of Libra'. It was stated in Lesson ~O, that the ascend.
ing node of Mercury was in the middle of Taurus,
and his descending node in the middle of Scorpio. This
will be fully illustrated by Map 6, where the line of his
nodes is shown, aad their longitude marked. The m,p
49
LONGITUDB OF PLAluITS' ASCBNDIXG NODBS.
represeots the plane oC the ecliptic, and when placed ID
the south side of the schoolroom, corresponds with the
position oC the ecliptiQ in the heavens. The north side,
or side towards the learuer, is oonsidered as ahove the
ecliptic, and the south side below it. To pass the plane
of the ecliptio, therefore, from South to North, is to
tUcend; and to return from North to South is to de8cend.
The arrows Dearest the sun show not only the direction
of Mercury t a8 he moves in his orbit, but also his relati ve
distance from the SUD, and the position of his nodes in
the ecliptic. The entire line of Venus's nodes is also laid
down ,on the map, together with her distance from the
eUD, and direction, shown by the arrows crossing the line.
In astronomical tables, the longitude of the ascending
node only is given; for when this is ascertained, that of
the descending' node is easily inferred from it. Take for
instance, the a~nding node of Mercury: it is laid down
OD the map b8 in longitude 46 0 •. Of course, then, hi.
descending DOcIe is in thC!ropposite side of the ecliptic, 9f
just 1800 distant. Add 180 to 46, and we have~tI26, tii~
actual longitude of his descending node, as showIl by the
map. So by adding 180 to 75, the longitude of Venus'.·
ascending node, we have 255, the longitude of her descending node. I have therefore given only the longitude
of the ascending nodes of the planets, and one half the
line of their nodes on the map; leaving the longitude
,lfthe descending nodes to be ascertained. in the manner
already explained .
. The longitude of the ascending nodes
the planets
respectively, is as follows:
or
or
Mercury -
•
-
460
Venus - • - - 75
Earth. - • •
Ceres •
•
•
800
•
Pallas - • • • 173
Jupiter. - - 98
Satttm. - • • 112
Herschel - - • 72
Le Verrier-undetermined.
Mars • • • - 48
Vesta • • - • 108'
Astnea . - • - 120
Juno • " - • 171
This subject JJhould be well . understood before the
learner dismisses it, to euter upon the next leuon •.
· 5 '
•
.00
CORSTBLLATIONS OF THB ZODI&C.
Lesson 36.
CONSTELLATIONS OF THB ZODIAC.
(Map 6.)
Bv this time the student is no doubt anxious to know
the "meaning of the strange-looking figures that .are
placed around this map, in the signs of the Zodiac. It
must not be forgotten that a lign is merely the twelfth
part of a circle. The largest circle on the map is divided
into signs, as well as into degrees. In each sign, and
outside of the circle, is placed a picture of some kinda bull, a lion" a lady with wings, a goat, or some other
figure. The reason for this we will now explain.
Outside the divided circle on tile map, and around the
different fieures or pictures, may be seen numerous star,.
Some are larger than others, and they seem to be scatJ
1
tered about at random. Such is the natural appearance
~
. of the bea vens generally, in a clear night, as well that .
belt stretching over from west to ~ast called the Zodiac,
as any other portion. Now the ancients imagined that
the stars were thrown together in clusters resembling
different objects; and they consequently named the'ifferent groups after the objects which they supposed them'" .
to resemble. These clusters, when thus marked out by
the figure of some animal, person, or thing, and named
accordingly, were called ConatellafiO'll.8.
As every part of the Zodiac is filled with stars, each
sign has one or more of tbese ancient constellations. It
is on this account that the figure, supposed to be represented by the constellation of each sign, is still retained;
and the signs bear the names Df their respective constellations.
The pupil will now more clearly discover the folly of
the idea- that each sign or constellation of the Zodiao
"governs" a particular portion of t:le human body, 88
stated in some almanacs.· How preposterous the notioD
TBB SUN'S APPABBlfT KOTIOK IX TBB ECLIPTIC.
61
that ~ cluster of stars, millions of miles from our globe,
govern a man's head, his arms, or his feet! And yet
sdme still think the "signs" should be consulted in refer.
ence to many important matters.
The names of the signs have already been given in
Lesson 27, to which the learner may again tum, to re.
fresh his memory, in conneotion with the map now beCore
hinGe
.
Les80n 37.
THE SUN'S UPA.RENT MOTION IN T1m ECLIPTIC.
(Maps 5 and 6.)
In Map 5, Fig. 1, the earth is seen performing hel
annual journey around the sun. Now when the earth is
in the sign :0: the sun will appear to be in cr; and as the
earth moves on to 111., the sun will appear to pass around
to ~. Hence, as the earth pass8s around in her orbit
every year, from west to east, it is obvious that the "Uft
will appear to make the circuit of the heavens in the
same time, and in the same direction.
.
;.. ',. .. All .the constellations of the Zodiac seem to overtake
aDd pass by the sun westward once a year; or in other
, words, the sun appears to meet and pass through them all
~astward, in regular order, every 365 days ..
Map 6 may ~llustrate this subject still more clearly.
The sun is seen in the centre. Around the SUll the earth
is seen in her orbit, the arrows showing her direction.
Now when the earth is in ~, in November, the SU~ must
seem to be in 111, on the opposite side oC the ecliptic. So
when the earth is in n, the sun will appear to be in I,
&0.
On the 20th of March the ear(h, is in longitude 180,
or in the first degree of =01; at which time we s'-l the lUn
enters cr.
.
The time of the 8un'. entrance into the different sip
is as {ollowa:"....
62
SUCCESSIVE APPBARANCB OF THB CONSTBLLATIONS.
cr, ,March
September 23d.
111., October 23d.
.
I, November 22d.
~, December 21st.
=, January 20th.
February 19th.
It must not be forgotten that this motion oC the sun
eastward around the Zodiac, is merely apparent; and is
caused 'altogether by the revolution of the earth around
the SUIl. By following the earth in her orbit from March
20th, around to the same point again, th~ sun will seem
to enter all the signs, in the order, and at the times speci'fi~d in the foregoing table.
As we have our spring while the sun )8 passing
through 'r, ~, and II, these are called the spring signs;
~, bt, and "R, are the 'BUmmer signs; :Or, fIl, and t, are
the autumnal signs; and "', =, and
the winter signs.
This subject will be still further illustrated in the next
lesson.
20th.
~, April 20th.
II, May 21st.
§, June 21st.
&\., July 23d.
1lR, August 23d.
:0=,
.
*,
*,
Lesson 3S.
SUCCESSIVE APPEARANCE OF THB CONSTELLATIONS IN TO
NOCTURNAL REA VENS.
(Map 6.)
Weare very apt to suppose that because we see no·
Itars in the daytirne, there are none in the heavens above
us. This is an erroneous conclusion. Were it not for
the light of the ,sun, the stars would shine ou~ as brightly
during what we now call. the daytime, as they ever do in
the night; but instead of seeing the same constellations
that we see in the night, at any given time, we should
see those only that were visible in the night 8iz mont"" ,
before; and would be above the horizon again in the night
six months afterwards.
The fixed stars surround the solar system in every
direction; and the fact that we cannot see the stars beyond the sun, 'or in that half of the Zodiac in which he
DISAGRBElIBNT .BBTWEBN THB KONTBS AND SIGNS.
63
appears, (on account of his superior light,) is no proof that
suoh stars do Dot exist and shine. W hen the sun is te>tally eclipsed, the stars appear in the daytime; and if
we look through a long tube or descend into a deep' well,
80 as to sh ut the strong light of the sun from the eye, the
stars may be seen even at noon in the heat of summer.
Let this subject be illustrated by the map. Suppose a
person to be observing the constellations of the Zodiac
on the 21st of June. At midnight all the constellations
(rom :01 around to cr would be in sight; but at twelve
o'clock the next day, when the other half of the Zodiac
would be above the horizon, the sun would be between
the observer and the signs II and ~, and would shed 80
strong a light over the whole visible heavens, a8 to eclipse
or obscure all the stars.
But as the earth passes on in her orbit, and the SUD
seems to pass the signs eastward in regular order, the
constellations will arise earlier and earlier every night;
so that all of them will seem to pass over from east to
west in the night. in the course of a year.
This map may be used to show what constellation.
will be on the meridian at twelve o'clock, or at any other
hour of the night, during every tnonth in the year. In
December they will be II and $; in March "R and .0.;
in June t and ~, &0., as the earth advances eastward
in her orbit, and turns from west to east upon her axis •
.,
. Lesson 39.
DISAGB.BBKBNT BETWEEN TilE MONTHS AND SIGNS.
(Map 6.)
The names of the months are marked around on the
map from we.st to east, to show at what time the earth 0ccupies any particular place in her orbit; and also when
the sun enters the opposite sign. But the months and
the signs do not exactly agree in longitude. The earth
reaches long. 1800 , and the sun enters T on the 20th or
~.rch; 80 that ~here are eleven days of March left aftel
the earth has passed into =0=, and the SUD baa entered ".
6-
THE BQUINOXES.
()f course,
then, all the months in the year are a little
more tardy, so to speak, thaD the signs; and are rep ra: ,
lented, in the map, as jutting by them eastward about
ten degrees of longitude.
Lesson 40.
THE EQUINOXES.
(Map 6.)
The great circle of the Zodiac is divided into four
parts, by imaginary lines running through the centre of
the sun, and at riCht angles with each other. On the
map they are dottet4. to distinguish them from others, one
running perpendicularly, and the other horizontally. The
.. earth is represented as being at the points where these
lines cross her orbit.
Two of the,e points, namely, the upper and lower,
are called the equinoctial points. They are so called because when the earth is at either of them the sun shines
perpendicularly on the equ~tor, and consequently to each
pole; and the day. and nightfl are of equallengtA all over
the world.
The plane of the equinoctial passes through the earth'.
equator; or, in other words, it is the equator of the earth
" extending off into the heavens in every direction.
•
The earth passes the equinoctial points on the 20th
of March and the 23d of September; the first of which
is called the 'Vemal, and the latter the "u'umfUll equinox.
These points being in opposite portions of the heavens,
are, of course, 1800 apart, as appears by the map.
Lesson 41.
'PRECESSION OF
TH~
EQUINOXES.
The best explanation of this nice and intricate motion
with which we have ever met, is from the pen of the
PUCESSION OP THE BQ11UfODS.
lalb~nted
55
Burritt; and &8 we have DO wiah to affect
originality at the expense of utility, we inae~ the follow.
ing extract for the perusal of the student. It is taken
(rom a chapter on the subject in the cc Geography of th(,
Heavens."
" Of all the motions which are going forward in the
Solar System, there is none, which it is important to notice, more difficult to comprehend, or to explain, than the
PRECESSION OF THE BQUINOXES,' a8 it is termed.
"The equinoxes, as we have learned, are the two opposite points in the earth's orbit, where it crosses the
equator. The first is in Aries; the other, in Libra. By
the preee88ion of the equinoxes is meant, that the intersection of the equator with the ecliptic i. not always in the
same point :-in other words, that the .~un, in its apparent
annual course, does not cross the equinoctial, spring and
autumn, exaotly in the- same points, but every year a
little behind those of the preceding year.
"This annual falling back of the equinoctial points, il
called by astrooo01er8, with reference to the motion of the
beavens, the Prece,sion of the Equino:re8; but it would
better accord with fact as well as the apprehension of the
leamer, to call it, as it is, the Rece8aionof the Equinoxes:
for the equinoctial points do actually recede upon the ·
ecliptic, at the rate of about 5ot" of a degree eve.ry year.
It is the name only, and not the position, of the equinoxes
.-:hich remains permanent; Wherever the sun crosser
the equinoctial in the spring, there is the vernal equinox
and wherever he crosses it in the autumn, there is the au
tumnal equinox; and these points are constantly moving
to the west.
"The sun revolves from ODf' equinox to the same equinox again, in 865d. 6h. 48' 47/ .81. This constitutes
the natural, or tropical year, because, in this period, ODe
revolution of the seasons is exactly completed. But it ii,
meanwhile, tQ be borne in mind, that the equinox itself,
during this period, has not kept its position a(llong the
stars, but has deserted its place, and fallen back a little
to meet the sun; whereby the sun has arrived at the
eq niDOI: before he has arrived at the same position among
56
THE t;OLSTICBS.
the stars from which he departed the year before; and
consequently, must perform as much more than barely a
tropical revolution, to reach that point agaiJl.
"To pass over this interval, which completu the BUft'.
8idereal revolution, takes (201' 221'1'.94) about 22 minutes
and 23 seconds longer. By adding 22 minutes and 23
seconds to the time of a tropical revolution, we obtain
365d. 6h. 91n. 10:8. for the length of. si,clereal retJoluticm;
or the time in which the sun revolves from one fixed star
to the same star again.
"As the sun describes the whole ecliptic, or 3600, ir
a tropical year, he moves over 59' 811'1' of a degree every
day, at a mean rate, which is equal to 5011'1' of a degree
in 20 minutes and 23 8~conds of time; consequently he
will arrive at the sam~ equinox or solstice when he is
50!" of a degree sl~ort of the 8ame star or fixed point in
the heavens, from which he set out the year before. So
that, with resper,( to the fixed stars, the sun aod equinoc• tial points faU back, as it were, lOin 7Ii years. This
will make the stats appear to have gone forward 10 , with
respect to the 8igna in the ecliptic, in that time: for it
must be observed, that the 8ame. aigna alway, keep in tIuJ
Bame points of the ecliptic, without regard to the place of
the cDnltellati0ft8. Hence it becom~s necessary to have
new plates engraved for celestial globes and maps, at
least once in fifty years, in order to exhibit truly the al.
tered position of the stars. A t the present rat.e of motioa..
the recesaion of the equinoxes, as it should be called, or
the prece88icm of the stars, amounts to 300 , or one whole
sign, in 2140 years."
Lesson
4~.
THE SOLSTICES.
(Map 6.)
The dotted line running horizontally across the map
is the lloe of the solstices; and the points where this line
crosses the earth's orbit are called the 80utitial poi,,".
57
TBB COLl1JlBS.
At the time of tb~ autumnal equinox, Septemoor 23d,
the sun is directly over the earth's equator, and his light
extends to both poles, as shown on the map. From thi.
time to December 21st, the SUD declines south, till it is
perpendi~ular over the tropic of Capricorn, (so called
(rom the sign which the sun enters on that day,) woeD
its Southern declination is stayed or ce~s. Hence the
Dame solstice.
From December 21'" to March 20th the lun approaches the equinox, which it reaches at the latter period, when h8 begins to decline northward, till on the 21st
of June he reachetf the tropic of CaRcer. He is then at
the 6U1n.mer solstice. From June 21st to September 28d
the sun agairY."fipproacbes the equator or equinox, at
which time he begins again to decl ine south, &0.
This declination of the sun north and south, and hi&
apparent passage through ~he plane
the equinoctial,
. twice a year, are caused by the inclination of the axis of
the earth to the plane of the ecliptic, and her revolution
around the SUD. What we have here said will serve
more fully to illustrate Lesson 25, where the obliquity.
of the ecliptic is considered.
or
Lesson 43.
THE COLURES.
...
(Map 6.)
The Colurel are two great circles crossing at the pole•
.'!I the ecliptic, (see Lesson 24,) and passing through the
. ecliptic at right angles. One passes througb the equinoxes, and is thence caned the Equinoctial Colure; the
other passes through the solstices, and is called the Solsti.
tial Colure. They are to the heavens what four meridi.
ana, each 900 apart, would be to the earth. They divide
the celestial sphere into four parts, like quartering an apple. Two hoops of wire, crossing between the eye of the
student and the sun, and also directly beyond the sun on
the other side of the map, would represent the colures;
,
58
PBRIHELION ANIJ APBBLION.
provided one paased through the map at the solstitial, and
the other at the equinoctial points. When once the place
of the colures is clearly ascertained, they are very COD.
venient in finding particular stars or constellations either
north· or south of the ecliptic.
'
Lesson 44.
ELLIPTICITY OP THE P!NETS' ORBITS.
(Map 7'.)
..
•
1
i
•
i
I
Thus far we have proceeded upon !Ie supposition that
the orbits of the planets were exact circ~s, and that CODsequently the several planets were· al waj't at the 8am~
distance from the 8U~ I t is time DOW to state more definitely tb.~ true figure of their orbits.
Fig. 1 represents the earth as revol ving in an ellip8e,
or cmal-a.Aaped orbit. This is its true figure; and indeed,
to a g,e~t extent, the figure of all the .planetary orbits.
But some ·~re more elliptioal than others, and the orbits'
of the comets, ~,shown in Maps 2 and 5, are more elliptical than thos8 ..of.'~~y of the planets.
Not only. are 1fle', orbits of the planets elliptical, but the
sun is always found one side of the centre, or Dearer one.
end of the ellipse than the other, as shown on the map.
The point where the sun is placed is called one of the foci
of the ellipse.
~
Lesson 43.
PBIlIBBLION AND APRELlqN.
(Map 7.) .
Wilen a planet or comet is in that part of its orbit near.
est to the SUD, it is said to be at its perihelion; and wilen
at the point most distant, at its aplaelitm. So of the mOOD ;
perigee and apogee are the points of her orbit nearest to
and most distant Crom the earth.
On the map the earth is seen at her perihelion on the
left, and at her aphelion on the right, the two points being /
•
...
I '
,\'
I
i
I
.1
59
BCCENTRICITY OF THE PLANETS' ClllBITS.
at very unequal distances from the sun. In stating the
distances of the solar bodies, we sometimes give their pee
rihelion and apheliOfl, as well as their mean or average
distances; but in Lesson 8 the mean distances only are
given. The following table will exhibit the longitude oC
their periheliMls, respectively:
Mercury.
.Venus
•
•
•
•
•
•
.lar~h
Mars
Vesta
Astrrea
•
•
•
•
JUDO
•
•
•
Ceres
Pallas
•
Jupiter •
Saturn •
Herschel.
La Verrier
•
•
•
•••
•
•
•
•
•
•
•
•
•
•
74 0
128
99
332
249
21'
43
46"
31
4
53
5
30
23 .. 56
33,"' 24
27 54
83 46
•
•
•
•
•
•
147
•
•
•
•
•
121
11
7
7'
8
89
9
167
31
299
11
"•
•
•
135
•
53
•
•
85
30
16
00
Lesson 46.
ECCENTRICITY OF THE PLANETS' ORBITS.
(Map ... )
The ecce'f&tricity of a planet's orbit is the tli8tance of it.
U!.~ the centre of the aun. This will be easily UD·
ders·
observing Fig. 1, where the sun is seen in the
left-han
cus of the ellipse, and upon the large maps,
about two inches from its centre.
These two inches would, in this case, constitute the
,
ecoentricity of the ellipse.
The ecoentrioity of the orbits or the different planets, .
is as follows:
Mercury
7,000,000 miles.
•
•
•
Venus •
492,000 "
•
•
•
Earth
1,618,000 "
•
•
•
•
Mars
•
• 13,500,000 "
•
•
Vesta
•
•
• 21,000,000
•
"
62
RIGHT ASCENSION.
Fig .. 2 shows the position of the sun at the time of the
equinoxes and solstices; the manner in which his light
strikes the earth at these times; the :one, of the earth;
the extent of the sun's declination, &0.
Fig. 3 is still more full and explicit. In addition to
what is contained in Fig. 2, it shows the place or decli.
nation of the sun for every month in the year, and the
manner in which his beanis strike the middle of both the
temperate zones during every successive month. Take.
for instance, the north temperate zone, at the 45th degree
of latitude. On the 21st of December, when the sun has
the greatest southern declination, and, as shown in Fig. 2,
shines vertically on the tropic of Capricorn, he would
seem to be quite low down in the south, even at noon;
and his rays would strike the north temperate zone quite
obliquely, as shown in the figures. From December
21st to June 21st the sun advance. to*aros the north,
and the obliquity of his rays constantly diminishes. On
the 21st of June the light falls quite obliquely on the
southern hemisphere, where it is then winter. The two
lines running off from the earth's surface to the 1ettet Z, .
are designed to show the perpendicular and zenith of the
45th degree of latitude; and also how much the sun
lacks of being direotly overhead at these points, at the
time of the solstioes.
I t will be easy to see from these figures that declination
18 to the heave",,' ",kat latitude it to the earth.
They may
De used, also, to show the use of a quadrant, a~ the
manner of determining latitude by the sun'~ .-. Idian
altitude, and his declination.
Lesson 49.
BIGHT ASCBNSION.
(Map
6.)
Rig'lat A,cenrion is distance east of the vemal equinox,
measured on the equinoctial.
In Lessons 33 and 34, it was shown that celestial lau.
,..
63
INCLINATION OF AUS TO OB.BITS.
tude and longitude answered to terrestrial, exoept that in
the Cormeroase we reckoned from ~nd on the ecliptic, in.
stead of the equinoctial. .
On the other hand, declination and right asoension re.
fer directly to the equinoctial; and consequently ans\ver
.to"longitude and latitude on the ~arth.
The learner may here start the inquiry, Why were not
declination and right ascension oalled celestial latitude
and longitude, seeing that they refer to the celestial equa.
tor, instead of measurements from and on the ecliptic 1
Such Ii question is not easily answered. This interchange
of terms, as it may be called, is rather unfavorable to a
ready and clear understanding of these topics. Even at
this late period it might be a service to the science in the
end, to call declination oelestial latitud~, and right ascension celestial longitude.
.
Right ascension is reckoned around on the equinoctial
to 360°, answering to 3600 or celestial longitude, only
that one is reckoned on the equ.inoctial, and the other on
the ecliptic.
l.
Lesson 30.
INCLINA.TION OF THB AXES OF THE PLAKET8
PLANB OF THEIR RESPECTIVB OB.BITS.
•
TO
TBB
,
(Map S.)
T~ pupil may fully understand this lesson, it may .
be ~~ii ;lecapitulate some things already learned .
1st. The Ecliptic is described Lesson 23. .
2d. The Orbil8' of the planets are described Lessons 4,
43, and 45.
3d. The inclination of the orbita to the plane 9f the
ecliptic is the subject of Lesson 32.
We now call attention to the inclination of the ozu or
the several planets to the plane of their orbits.
This is a lesson of great interest and importance; and
although so far as the earth is concerned it has already
been anticipated, in our remarks on the seasons, d~clina-
64
INCLINATION OP AXES TO .aBITS.
non, &c., still it opens a rich field of inquiry before the
Itudent, and should receive a good degree of attention.
On the map the dotted horizontal lines represent por.
tions of the orbits of the planets, with the exception of the
sun, in which case they represent the plane of the ecliptic.
The azis of each planet is seen inclined to the plane of its
orbit at its true angle. The equators are shown by the
dou ble lines crossing the axes at right angles. The zonu
are distinguished by curved boundary lines, and by the
different colors--the torrid zones being red, the temperate
green, and the frigid white.
It will readily be seen that the extent of the torrid zone
of a· planet depends altogether upon the amount of its
polar inclination. If its axis be much inclined, as in the
case of Venus, it will have a wide torrid zone; but if its
axis is but little inclined, like that of Jupiter, it will have
a narrow torrid zone.
The sun's declination north and south of the equator
of each planet must be just equal to its polar inclination ';
and as its torrid zone includes both its northern and
southern declination, it follows that .it must be twice as
wide as the alDount of its polar inolination.
These prinoiples will be more olearly seen by the fol.
lowing table, in which the polar inolination, greatest de.
clination, and width of torrid zone, are oompared :
Inc. of axia.
Declination.
;:0,00'
Torrid zon•.
Venus • • • 75 0 O<Y
75° 00'
66
Earth • • • 23 28
23 28
Mars • • • 28 40
28 4:0
57 20
Jupiter • • •
8 5
8 5
6 10
Saturn • • • 80 00
30 00
60 00
The SUD • •
7 20
Only the first part of this table nee~ be committed to
memory; but the whole should be studied and compared
with the map until its principles are fully understood.
or Mercury, the Asteroids, Hersohel, and Le Verrier,
nothing definite is known respeoting their polar inolina.
tion; oonsequently we have no knowledge of the extent
of their zones, or the charaoter of their seasons.
66
Lesson 31.
SEASONS OF THE DIFFEB.ENT PLANBTI.
(Map S.)
The general philosophy of the seasons, together with
the seasons of the earth, are already explained in LessoD
46. The same subject will now be resumed, as it relatel
to the rest ot the pI anets.
The seasons of the planets depend upop two causes:
the inclination of their axes to their respective orbits, and
their periodic revolutions around the 8un. The former
determines the eztent of their JOne8, and the latter the
length of their 8etUOM.
The effects df polar inclination are seen in the contrast
presented by Venus and Jupiter. Venus, with a polar
inclination of 75°, has a torrid zone 15()O wide; while
Jupiter, whose axis is inclined but 3° 5', has a torrid zone
only 6 0 10' wide. After the statement, of these general
principles, w.e shall proceed briefty to notice the seasons
of the several planets.
It might be well, however, for the student to turn back to
Lesson 46, and review it in connection with this map.
Especially let him examine the figure of the earth and
her zones with a view to the obliquity of the ecliptic, explained in Lesson 25. Call to mind al80 the subject
the..aun's declination, Lesson 47, and the difference be.
tween r~rring to the ecliptic, as in celestial latitude and
longitude, and to the equif&Octial,8s in right ascension and
deolination. See Lessons 83, 34, 4:7, and 4.8.
or
Lesson 3t1.
SEASONS OF VENl7S.
(Map S.)
The tropics of Venus are 75 0 from her equator, ~d
within 150 of her poles. She has no frigid zone, or polar.
6*
,
66
SBA.SONS OF !IIA.RS.
circles. Her periodio time being only 225 days, (Lesson
18,) the sun passes in that'short time from her northern
solstice through her equinox to her southern solstice, and
back to the point from which he started. So great is the
sun's dec1i9ation on Venus, that when he is over one of
her tropics, it is winter not only at the other tropic, but
also at her equator; and as the sun passes over from
tropic to tropic, and back a,gain every 225 days, making
spring at the equator as he approaches it, summer as he
passes over it, autumn as he declines from it, and winter
when he reaohes the tropic; it follows that at her equator
Ven us has eight ,ea,01I8 in one of her years; or in 225 ol
our days. Her seasons, therefore, at her equator, consist
of only about four weeks of our time, or 28} days; and
from the heat of summer to the cold of winter can be only
about 56 days. At her tropics she has only four seasons
or 56 days each.
A t first view it might appear to the reader that such
an arrangement must be fatal to all vegetable life, especially at Venus's equaior; but it should be remembered
that He who inclined the axis of Venus to her orbit, and
pre8Cr~bed her periodic time, could as easily clothe her
with vegetation of a month's growth, as with that requiring the lifetime of the oak or the cypress to bring it to
~Tfection.
Lesson 33.
SEASONS OF MARS.
•
(Map S.)
The polar inolination and zones or Mars are very
similar to those of the earth; but owing to the difference
of his periodic time, his seasons are very different from
ours. His year of 687 days is divided ~nto four seasons
of about 172 days each, or nearly twice the length of the
seasons oC the earth.
Hjs 'polar inclination is 50 12' greater than that of the
earth; making his torrid zone wider, and his polar
oircles greater than ours; while his temperate zones are
IOmewhat narrower •
•
• .'SOKI OP JUPITBll.
67
Lesson 34.
8BA80N8 OP 11JPITBll.
(Map
8.)
80 slight is the inclination oC J upiter'a axil to hi,
orbit, that it affords him but a very narrow torrid zone.
The inclination of his orbit to the ecliptic is but 10 16',
and his axis is inclined to his orbit but 3 0 5'; 80 that his
axis is nearly perpendicular to the ecliptic. The BUD
never departs more than 30 6.1 from his equator, and still,
as his periodic time is about 12 years, (Lesson 18,) he
has alternately six years of northern and six of southem
declination. His narrow torrid zone and small polar
circles leave very extensive temperate zones. In paaaing from his equator to his poles, we meet every variety
of climate, from the wannest to the coldest, with but
slight variatioDs in any latitude, from age to age. His
days and nights are always nearly of the same length, as
the sun is always near his equinoctial. His poles have,
alternately, six years day and six years night.
In connection with the above facts, it may be well to
8880Ciate the amount of lWht received by this planet; bie
rnagnitu.d,e; his oblate frRure; his rapid roto.tion upon hie
axis; and his distance from the sun. The student can.
Dot too often call up the facts already learned, as he ad.
vances from lesson to lesson. In this way he will 8000
be able to.state the most interesting particulars r~peotiDg
each of ilie solar bodies.
Lesson 33.
SBA.SONS OP SATUllN.
(Map 8.)
The polar inclination and zones of Saturn differ but
liUle frorn those oC Mars; but his seasoDs are greatly
modified by the length of his periodic time. This being
about 30 years, his four seasons must eaoh be about 7i
68
years 1000g; and his polar regions must have, alternately,
15 years day, and 15 years night.
The Rings of Saturn which lie in the plane of his
equator, and revolve every'
hours, are crossed by the
sun when he crosses the equinoctial of the planet.
During the southern declination of the sun, which lasts
fifteen years, the 80uth side of the rings is enlightened,
and haa ita summer. It has al~ its day and, night, by
revol ving in a portion of the planet's shadow.
When the sun is at tbe southern tropic, it is midsummer OD the south side of the rings; as tbe rays of light
then fall most directly upon them. As the SUD approaches the equator, the t~perature decreases, till h~
crosses the equinoctial, and the long winter of fifteeD
years begins. At the same time the north side
the
riDgs begins to have its spring; summer ensues, and in
turn it has fifteen years of light and heat.
The Rings of Saturn will be turned directly towards
the earth, about the middle of September, 1849; at
which time the light of the '8un wijl extend to both pole.
of the planet. Of course Saturn is then at one of his
equinoze,. Seven and a half years after, he will reach one
of his 8OLmcu-his rings, as seen, will appear fully expanded from the earth,-the sun will have his greatest possible declination from Saturn's equinoctial, and it will be
wi~ter at one of his poleSt and summer at the other.
In seven and a half yean longer, he will reach his other
equinoctial point, and his rings will be invisible again.
Saturn's Rings will be invisible from the 22p of April,
1848, until January 19th, 1849; excepting that they
may be aeen from the 3d to the 12th of September, 1848.
or the I8880DS of Saturn, and the structu~, dimen.
sions, and uaes of his won~erful rings, we shall remark
rurther hereafter in a distinct lesson, in connection with
Map 11.
From Map 8 and the rOTegoing remarks, it must be
obvious to the leamer that cold and heat, winter and Bum.
mer, "seed-time and harvest," are not peculiar to our
globe, but are characteristio
every world with which'
we are to any oonaiderable extent acquainled.
lot
or
or
..
1
I
Lesson 36.
CONJUNCTIONS AJf~ OPPOSITION OF PLANBTS.
(Map 9.)
•
"
When any two or more of the solar bodies are found
ill tJ&e 8ame longitUiU, they are said to be in conjuflCtitm.
Fig. 1 represents the Sun in the centre, and Venus, the
Earth, and Mars, at different points in their orbits. Ie
the Earth was at D, and Venus at I or S, she would be
in conjunction with the SUD, both appearing to be at a
point between ~ aod II, or according to Map 0, in the
60th degree of longitude.
The interior planets have two conjunctions; the anfe.
rior conjunction, when between the earth and the SUD, as
at I ;. and the 81¥p6rior conjunction, when beyond the SUD,
as at S. At the superior conjunction the enlightened
side of the planet is towards the earth; and at her infe.
of
rior, the dark side.
When at her superior conjunction, Venos is 154 mil.
lions of miles Crom the earth, but when at her inferior
conjunction, she is only 26 millions of miles distant. The
reason for this great difference will be seen by a glance
at the map; whicb shows ber the whole diameter of her
ol"bit farther off when at S than at I.
. The uterior planets have a n.perior conjunction, as
Mars at N; but they can never get between the earth
and the sun to form an inferior conjunction. When,
therefore, \fa planet gets in the same longitude al the
earth, like Mars at F, it is said to be in 0pp08ition •
A planet in conjunction rises and sets nearly with the
Bun; but one in opposition rises when he 8ets, and seta
when he rises.
.
The position of planets with respect to each other is
sometimes represented by an astronomical sign. Thus d
denotes conjunction, and 8 qppo8ition~
LeasOn 32 shows the orbit of Venus to be inclined to
that of the earth at an angle of 3jP; hence as one half
of her o.rbit is above the ecliptic, and the othel half below,
70
BIDEBBAL £1(D SYl'fODIC UVOLnIORS.
ahe will always appear either above or below the sun
when in .conjunction, except when she is at one of her
nodes; in which case she will appear to pass over the
sun's disc, as represented in the figure. See Lesson 81.
Lesson 37.
SIDBREAL AND SYNODIC RBVOLUTIONS.
(Map 9.)
The 8idereal or periodic re1)olution of a planet is its
passage from any particular point in its orbit, around to
the same point again.
A ,ynodic re-oolutUm is one extending from either an
inferior or superior conjunction to the same conjunction
again. It is therefore considerably more than one com.
plete revol UtioD around tbe sun ..
For example: were the earth stationary at D, the su.
perior conjunction of Venus would happen 112j- days af.
ter her inferior conjunction; or in just half ber periodic
time; but as both are in motion in the same direction, one
revolving in 365 days, and the other in 225, it is obvious
that when Venus reacbes the point I, the earth will be
(ar behind; and when the earth reaches D, Venus will
have advanced to M in her second round; and will then
have to overtake the earth before an inferior conjunction
can be effected. This will occur when the earth reaches
the point L in her second rou~d.
From one inferior conjunction to another is t94 days;
requ~ring about 2f revolutions of Venus, and nearly If
revol utioDs of the earth.
.
The periodic times of the planets were given in LeaIOn 18; but for the sake of a better understanding of the
subject, the sidereal and synodic periods will here be
. given in connection. They are as follows:
Sidereal.
Mercury
Venus
•
Earth
•
•
-
88 days..
• 225"
•
• 865"
•
Synodic.
115 days.
594 "
866 "
IIDBUAL AND 8YJlODIC DV'OLVTlOKI.
8ldereal.
I
.)'Bodic.
Mars •
1 year-322 days. •
780 days.
Vesta •
•
8"
230"
•
608 "
..
4"
105 "
476 "
Astrma
JUDO.
•
4"
131"
474 "
Ceres •
4"
222"
•
466 "
Panas •
.."
222"
•
466 "
Jupiter
• 11"
317"
•
399"
Saturn
• 29"
175"
378 "
Herschel
84"
-"
3691 "
Le Verrier • 217"
119"
•
366t"
This is an interesting table, and may be studied for
. some time by the more advanced student to great advantage. He may imagine Mercury hurrying round to his .
starting-point in 88 days, and in 27 more overtaking the
earth, even before she has performed one-third of her an.
nual journey.
The periodic time or Mars being nearly double that or
the earth, his synodic period is but little over two years.
By subtracting the earth's period from the synodic period
of the rest of the planets, the remainder will show how
long the earth is in overtaking the exterior planets re.
spectively, after she has completed one revolution. Thus,
the synodic time of VeMa is 503 days. In 365 days the
earth completes one revolution, and reaches the point from
which she set out. Vesta is then 365 days ahead of the
earth, but moving at a four years' pace; 80 that in 138
days the earth overtakes her, and they are again in COD.
junction. In the case of Jupiter, Saturn, &c., it requires stift less time. Their periods are long, and they
move slowly in longitude;. so that when the earth haa
completed a period, they are but a short distance in ad.
vance, or to the east of her, and she lOOn overtakes them.
By subtracting, it will be seen that the time required is,
for Jupiter, 34 days; for Saturn, 13 days; Cor Hersohel,
days; and (or La Velrier only If days. . Map 2
mIght be serviceable in illustrating this subject, 80 far .a
relates to the exterior planets •
The learner must Dot forget tbafAlle exterior planets
have but one conjuDction, while the illterior have two;
q
•
71
72
WHEN PLAKBTI AU SAm TO .B STA.TIONARY.
and that in the preceding table the time is given from one
conjunction to another of tAe
Idnd. The opposite
OOIlj unction occurs in just half the synodic period.
,a,.,
Lesson 38.
BLONGATIONS OF A PLAN.'!'.
(Map 9.)
.
The elongation of an interior planet is ita angular distance east or west of the sun, according as it follo~s or
precedes him. The greatest elongation of Venus is 480 ,
and that of Mercury only 290.
But these alternate elongations east and west are not
always the same. Those of Mercury yary from 160 12'
to 280 48'; while those of Venus vary much lesS. E
and W, on the map, mark the positions of Venus at the
time of her greatest elongation.
From the above facts several other important conclusions
are deduc~d. The first is, that the orbits of Mercury and
Venus are within that of the earth. If it were not 80~
they would depart farther from the 8UD, and sometimes
appear in opposition to t.hat luoVnary. In the second
place, they show that the orbit of Mercury is within that
of Venus; otherwise his elongation would equal or exoeed that of Venus. Thirdly, they show the ellipticity
of the «;>rbits of Mercury and Venus. If their orbits were
oomplete circles, their greatest elongation would alway.
be the same; but as it varies, it proves that t..y are Dot
always at the same actual .distance from the sun, or, in
other words, that their orbits are more or less elliptioal.
Lesson 39.
WBBK PLANETS ARB SAID TO BB STATIONARY.
(Map 9.)
For a short time, while at or Dear their greatest eloDlation, the interior planets Beem neither to recede from.
l
I
DI1lBCT ..AND RBTllOGUDB MOTION8.
73
nor approaoh towards, the SUD. They are then said to
be dati.ontIry. These periods &re just before and just after
an inferior conj uDction. They are represented in Fig. 1
at E and W. At E the planet would be coming touJartll
the earth, and at W gai"IJ from it.
Lesson 60.
DIRECT ..AND RBTROGRADB MOTIONS.
(Map 9.)
It was stated in Lesson 18, that the planets revolved in
their orbits from west to east, or in the order of the signs.
But they do not always appear io maintain this order.
At times they advance regularly through the signs, and
again retrace their course. Hence the distinction of direct and retrograde motions. Direct motion is from west
to east; retrograde
from east to west.
The general course of the planets is eastward, their
retrogtession being but for a short time, when the direot
course is again resumed.
The cause of this seeming irregularity will appear by
again consulting Fig. 1. The signs will be seen marked
", ~, II, &c., on the right and left sides of tbe map, and
may be imagined around the whole figure. When Venus
is at W, she would seem, to an observer on the earth, to
be in
in the signs of the upper figure. As she passed
OD in the direction of the arrows, from W to E, her motion
would be ttlirect~ -and she would seem to pass through
", ~, II, §, and into bl; but in passing from E to W
she would seem to fall back through ~, II, &0. These
are her direct and retrograde motions.
But the amount of apparent retrogression is greatly
reduced by the motion of the earth in the same direction;
88 for instance, if the earth advances only from D to the
lower ~and (o:T) during a revolution o(Venus, she would
not retrograde beyond the beginning of~.
The above priooiplea are as applicable to Mercury u
to Veoua.
is
*,
74
RftaOO• .ADB .OTJO.8 OP Brrs.loa PUKBTL
Lesson 61.
UTJ10GUDB MOTIONS OP TBB BITEBIOR PLAlfETS.
(Hap 9.)
The apparent retrogression of the exterior planets is
dected in a manner somewhat difFereDt from that of the
interior planets.
8dl'poate the earth at A, and Mars at B; he would be
leen BltlO&g the stars at C. As the earth gains upon
Mars, and fed.ches the point D, Mars, being at F, would be
seen at G, 01" west of where be was first seeD. When
the earth reaches H, and Mars is only at J, be will be
seeD at K; or ItOme 150 back, or west, of his first apparent position.
.
The part of the great circle of the heavens through
which a planet see~ns to retrograde, is called its arc Of
retrogradati.on. In the figure it is the arc of the circle
betlveen C and K.
The following table will show the arc of retrograde
motion, and also tl1e time of retrogression in days:Arc.
-
Day..
23.
Mercury
ISlo
Venus
16
42
Earth
16
Mars
78
13
83
Vesta
•
12
99
Astrma
•
12
Juno
.D9
•
99
Ceres
12
•
12
99
Pallas
•
10
121
Jupiter
•
Saturn
139
6
•
Herschel •
151
4
•
Le Verrier
180
1
•
•
Here it may be interesting to· observe, that the more
distant the exterior planet the less its aTC of ret rograd ation, and the longer its time. The reaSOD for this may be
illustrated by the map, Fig. 1. Suppose Mars at F to
-
-
VBNlJI AS EVENING AND ltIORNUfG STAlL.
76
represent Herschel. Now as his year consists of eighty.
four of our years, it follows that the earth would pass him
eighty-three times during one of his revolutions; and that
during a revol ution of the earth he would pus through
only {7th part of his orbit; or about Slo. The planet
F would thence seem to retrograde slowly on the eel i ptio
nearly half the year; or while the earth was passing from
A to H on the m a p . .
For the same reasons· the arc would be still less, and
the time ~f retrogression still longer in the case of La
Verrier. The more distant the planet is from the earth'.
orbit, the smaller the angle which will be necessary to
inel ude that orbit; and the less the arc of retrogradation
descril?ed by the planet on the concave of the heavens.
Lesson
6~.
VENUS AS MORNING AND EVENING STA••
,
(Map 9.)
.. Next Mercury, Venus runs her larger round,
With softer beams and milder glory crown'd ;
Friend to mankilld, she glittel'8 from afar,
Now the bright efJenin.g, now the morning star.
From realms remote she darts ber pleasing ra "
Now leading on, now closing up the day;
Term'd P hOllphor when her morning beam.. she yiel.,
And Heq'rus when her ru.y the efJening gilds."
It has been seen that in making her revolutions, Venua
is sometimes East Bnd sometimes West of the sun. From
her infer'or to her superior conjunction she is IDe,t of the
sun; and from her superior to her inferior conjunction
ea.t of him. N ow it is obvious that when she is west oC
the sun she will go down before him, and cannot be seeD
in the west after sunset; but if she sets before the SUD
she will rise before him, and can be seen in the east be.
fore sunrise. When, therefore, Venus is west of the sun. :~f~
she is morning star. When she is east of the sun she·. :t.~'
rises aftex the sun, and nlay be seen above the horizorr1n .'
. the west, after the sun is set .. She is then e",ening at,ar.·'
The .ancients supposed thpse were two different stars,
•
76
PlUgS OP
oaeny .ARB VBlfVI.
calling the fint Ploqluw, and the other.HeqtrU. Venus
is alternately one or the other about 292 days. For 146
days after her superior conjunction she lingers Carther and
farther behind the sun, in the west, till she reaches her
greatest elUtem elongation. Sbe then seems to approach
, the sun agaiD for 146 days, w heD she passes her inferior
oonjunction, and becomes morning star. After this she
rises more and more in advance of tbe sun for 146 days,
when, baving reacbed her greatest tDUtem eioDgatioo, she
begins to faU back again ~wards the 8UD, and in 148
days is at her superior conjunction. This passed, she i.
agai 0 evening sta r.
..' . .
Fig. 2 is designed fully to illustrate all that may yet
.em obscure to the learner. From W to E w~pre­
lent her direct motion, in the order of the sign~ ..From
E around to W again sbows her retrograde mOtion. S
and I mark her superior and inferior conjunctions; and
the .appearance of a 'rGuit is represented on the sun's
disc.
By imagining the sun and Venus as represented in th~
figure, to rise in the east and pass over to the west, the
student will see -that if Venul were at W she would he
morning star, and at her grFatest elongation; but it at E
abe would be evening star, &0. It would be a usefbl
exeroise to observe the exact position of V en us in the·,
heavens, at the time of studying these le880ns, and then
point out that positioD on the map.
.
LeSSOI
63.
PHASES OF IIBRCl1BY AND VElWS.
(Map 9.)
As Mercury and Venus are opaque bodies, like our
earth, only those portioDs of their surface appearing
bri~ht whioh are enlightened by the sun; a'nd as their
enhghtened sides are tu rned towards U8, little by little,
they present, when seen tbrough a telescope, all the cW:.
Ce,ent appearanoe8 or phases the moon•
or
•
•
TELBSCOPIC VIEWS 0. THE PLANETS.
77
Fig. 2 represents Venus in her orbit, and exhibiting
all her different phases, in the course of her revolutioo.
At I, her inferior conjuDction, her dark side is towards
us, and ber enlightened side invisible. As she pl188e8
from I to' W, and so on round to S,
see more and
more of her enlightened side, till her whole illuminated
disc is in view. From her superior to her inferior COD.
junction she continues to wane, till her dark side is again
turned directly towards the earth.
Although when at S, her whole enlightened hemi.
sphere is towards tire earth, still she is le88 brilliant than
when at -E and W; owing. to her increased distllnce
from us, and her being, apparently, in the neighborhood
oftbe sun.
It will be seen that Venus is the whole diameter of
her orbit nearer to us, at ber inferior conjunction, than
at her superior; and as her meaD distance-from the SUD
is 69 millions of miles, her distance from the earth must
vary to the extent of twice that amQunt, or the whole
diameter of her orbit, which is 138 millions of miles. It
. is not strange, therefore, that her apparent magnitude
undergoes sensible variations between her conjunctioDs.
we
Lesson
6~.
TELESCOPIC VIEWS OF THB PLANBTS.
I :
•
(Map
to.)
Although in the preceding lessons we have frequently
al1uded to th~ appearance of. lOme of the planets, wheD
leen. through a telescope, it is thought important to describe those appearances more in detail; and to ill ustrate
the descriptions by appropriate engravings.. This is the
.
object of Map 10.
Before any particular planet is noticed, it may be well
to state a few general facts respecting these primary
bodies.
1. They all have the same general figure, namely,
that spheres or spheroids •
or
.,.
78
TELESCOPIC VIBWI OP TBB PLANETS.
2. They all seem to be surrounded by an atmoqMre,
of greater or less density aDd extent.
.•
3. The spots or belts seen upon their surfaces (rom
lime to time, by different observers, seem to be in the
main permllnent, and indicative of large divisions of land
and water, like our continents and seas.
With these prelimin~ries, tbey will now be taken up
aDd considered in order.
MERCURY.
"Of MBRCURY," says Dr. Herschel, "we can see
little more than that it is rouod, and exbibits phases. It
is too small, and too much lost in the neighborhood of the
8UD, to allow us to make out more of its character." But
this is not the opinion of every obse"er. Mr. Schroeter,
an eminent German astronomer, assures us that he haa
not only seen 8pOtII on the surface of Mercury, but also
8IOU1&tai1l8, the height of two of which he actually measured. They were situated in the southern hemisphere
of the planet, and the highest was found to be Dearly
. eleven miles in height.
Numbers 1 and 2 on tbe map, are representatioDs or
Mercury. The spots supposed to have been seen by
Schroeter, are represented on his disc, and he has a faint
bluish tint as when seen through a telescope. As else.
where stated, he exhibits the different phases of the moon
during his synodic journey around the sun.
VBNUS.
•
The figures from 3 to 12 inc) usive, are telescopio
views of VenlU. As a whole they represent her various
,la,e,; as already explained in Le880D 63; and il.
lustrated by the lower figures of Map 9. Figures 8, 4,
11, and 12, show her horDed, 88 when near ber inferior
conjunction. Figures Q and 10 show her as sbe appears
wheD at her greatest elongation; 6 aDd 9 as gihbmu,
between her greatest elongation and superior conjunction; and 7 and 8 as she appears at her superior conjunction.
These ten views present a great varietyJ as it resp6ol11
TELESCOPIC VIBWS OP TUB PLANBTS.
79
or
the 'PO" that appear upon the surface
the planet.
They seem Dot only to vary in form, but al80 in their
number. It may be proper, therefore, to state that the.
views were not all had by the same penon, Dor during
the same period of time.
Fig. 8 is a view by ScAroeter, in 1791.
Fig. 4:
u
Bianchini, in 1726.
Fig. 5
"
Cunni, in 1667.
Fig. 6
"
" . in 1666.
Figures 7 and 8 represent the face of the planet, as it
is supposed she would have appeared, at the time of
sOme of the other views, had her whole hemisphere been
enlightened. It will be seen that each of these figuree
combine two other views.
Fig. 9 is a view by Schroeter, in 1790.
Fig. 10 is a view often bad by the celebrated Dr. Dick.
Figures 11 and 12 are repetitions of former views, with
the crescent inverted, in order to illustrate the subject of
V en us's phases.
The wrface ot Venul is variegated with moufttaiu,
some of which are estimated to be over twenty miles in
height. Three elevations have been estimated at 101,
Ill, and 19 miles, respectively.
The atmoqMre of Venus is supposed to surround her
to tbe depth of only about three miles; but it is 8upposed
to be very deus.
The color of Venus is a a/very ",hite. When at her
greatest .ongation, she is sufficiently bright to cause a
perceptible shadow if her light is intercepted .
.•
THB BARTH.
That the leamer may know the grounds of the inferences drawn from the telesC9pic lippea.rances oftbe planets, in regard to their geography, or their great natural
divisions, as continents, seas,· &c., we present him at
No. 13 with a tele,copic view of tke Earth. Let him
imagine himself placed upon Merr,ury, for instance, with
a good telescope, observing our planet. At the time of
80
TELBSCOPIC VIBWS OP. THE PLA.NBTS.
her opposition she would appear/wI from Mercury. The
continents and islands would appear brighter than the
rest of her disc; as they would reflect a stronger light
than oceans, seas, and lakes. By watching these spots
they would be found to cross the earth's disc in 12 hours,
from which the observer would infer. that our globe re.
volved on her axis in 24 hours; and from the direction of
the spots he would deduce the inclinatioa of her axis to
the plane of her orbit.
From the passage of cloud8 over her 8U rface, and other
phenomena, it would be inferred that tbe earth had an
atmosphere, and the different zones, and the changes of
tbe seasons, might present a variety of COltw8 to the celes.
tial observer~
To a person on one of the ezterior planets, the earth
would present all the phases of the moon.
The study of geography has no doubt made the learner
familiar with the figures of the continents, islands, &0.,
upon the earth's surface; but if he can divest himself
for a moment of all particular knowledge of our globe, and
contemplate her from a distance, as a planet, with w hat Dew
and surprising interest does it invest her! She not only
becomes one of a class, from which we may reason analogically respecting the physical constitutions aod design
of other worlds; but while we look with wonder upon the
planetary orbs, and long to know more of their physical
structure, we look upon the earth as the only orb which
IDe are allowed to visit, and with whose history ao<Oj pecu.
liarities we may now become acquainted. ~jd as the
student surveys the whole Western hemisphere, let him
inquire, " What iR man /" What is a city. an t:mpire, or
a tDOrld, in the great universe of the Almighty'
IIA.B.S.
ThA figures from 14 to 23 inclusive are representations
Mara. The first two, namely 14 and 15, are views by
Cassini, 8S long ago as 1610. They are copied from a
volume of the Transactions of the Royal Society of Lon.
don. Figures 16 and 17 represent views had by Maraldi,
a celebrated French astronomer, in 1704. Figures 18
or
•
TBLBSOOPIC VIBWI OF TIlE .L.A.KBTS.
81
and 19 represent the appearanoe oC the spots on Mara, as
eeen by Dr. Hook in 1666, from a drawing made at the
time by him. Figures 20 and 21 represent views by Sir
William Herschel, previous to 1784. Fig. 22 is a view
by Sir J oho Herschel, as copied by Nichol in his" Solar
System," and by several other astronomical writers.
Fig. 23 is' a view by Dr. Dick, iD 1832, aDd alllO in 1837.
It is Jopied, as several of the above are, from his "CelMtial Scenery."
.
It may seem impossible to the learner that all thj,
yariety in appearance could be produced by permanent
objects on the su rface of the planets; but let him remem.
ber that the map of Mars, which he is studying, is drawn
upon a sphere; and that the revolutions of a planet would
necessarily produce a constant change, not only in the
general appearance, but a1110 in the apparent form of the
spots.
The bright lpot on the upper end of Fig. !2, at the
planet's north pole, is supposed to be the reflection of light
from 81WfD and ice. This supposition is rendered probable
by the {act that the spot disappears as the north pole of
the planet is turned towards the sun, and returns again
with the departure of the direct rays of the 8UD, and the
retu rn of winter.
The nrface of Mars is variegated with oceans, seas,
aod continents, with mountains and vales, like all the
rest of the planetary bodies. "On this planet," lays Dr.
He~l,"we discern, with perfeot distinctness, the out.
lines 0
hat may be continents and seas." The cele.
brated
ler, of BerHn, constructed a complete map of
the surfaoe of Mars, with accurate delineatioDS of its great
Datural divisions, as one would draw an outline Dlap of
the world Crom an artificial globe.
.
The color of Mars is red, owing, it is supposed, to the
density of his atmosphere, which may color the whole
scene, 8S clouds put 'on a gorgeous crimson in the morning or evening sky. This oolor is not merely telescopi" :
it is the natural color of the planet as seen by the naked
eye; and by it he may easily be distinguished from the
fixed stara.
82
•
TBLBSCOPIC VIBWS OF SA-TUIlN.
THE A.STEROIDS.
Of the A steroiu very little is known, on account 0'
their distance and their diminutive size. A thin haze, or
nebulous envelope, has been observed around Pallas, su pposed to indicate an extensive atmosphere; but no' spots
or other phenomena have ever been detected. It is hoped
that if ever Lord Rosse returns from examining the distant ne bulle, he will give us some new light respecting
the bodies of the Solar System.
The Asteroids are never visible to the naked eye.
Through a telescope they have a pale ash color, with the
exception of Ceres, which in color resembles Mars.
1UPITER.
or
Fig. 24 is a representation of Jupiter,-the prince
planets. His natural color is 8 palish gell.()fJJ. His belt.
are seen where they are usually found, namely, on each
side of his equator, or in his temperate zones. The map
shows his flblate form, or the difference between his polar
and equatorial diameter.
'
What the belts of Jupiter are is uncertain. " They
are generally supposed to be nothing more than atmo.
qherical phenomena, resulting from, or combined with, the
rapid motion of the planet upon its axis." In number they
vary.from one to eight. Sometimes they continue without change for months, and at other times break up and
change their forms in a few hours. Dark spots are also
frequently seen in these belts, one of which was,;lDown
to maintain the same position for upwards or r~f1; years.
Lesson· 63.
'lBLBSCOPIC VIEWS OF SATUaN.
(Maps
10 and 11.)
Fig. 25, Map 10, is a telescopic view of Saturn with
his belta and ring,. The helt8 resemble those ot Jupitp,r.
already described. His rings will be noticed in conneotion \vith Map 11, to which the student is referred. The
I
,
TELESCOPIC VIBWS OP SA'ft'llK.
body
or Saturn
83
is of a lead color-the rings a ,U"erg
."hite.
Before the invention of the Telescope, Saturn \'188
known only as a distant planet, devoid of that special interest with which modern discoveries have invested him.
But since. the powers of that wonderful instrument have
been brought' to bear upon him, he has assumed new and
resplendent glories, and now stands forth to view as QDe
of the most interesting objects in the gorgeous heavens.
Though we have no room in this treatise to desc~be
the different kinds of telescopes, or to detail their history,
we propo~, nevertheless, to give some idea of their imprl1t1sment, by traoing the Iuccessi1'e step. by which we have
arriyed at OUf present knowledge of the planet Saturn.
The figures arranged across the top of Map 11 are
representations of a variety of telescopic views of Saturn,
by different observers, during a period of 45 years; Of
from 1610 to 1655. The variety in these appearances is
probably owing more to the various qualities of the telescopes used, and their general imperfection at that early
period, than to any other cause.
Fig. 1 is a view, had by Galileo, the inventor of the
telescope, in the year 1610. He supposed there were two
large satellites at equal distances from the body of Saturn.
Fig. 2 represents him as he appeared to Scheiner in 1614.
Fig. 3,is a view by Riccioli, in 1640. With the exception ,ot the convexity towards the body of Saturn, the figure
is a ~ty~ correct one so far as the rings were traceable.
Fil~~epresents Saturn as he appeared to HeZvetiu
in 1643.
Fig. 5 is another view by Helvetius, in 1649. The
rings were now traced much farther than ever before, and
thei r existence Q,6 ringa was considered highly probable.
Fig. 6 is a third, and still better view, by the same ob•
.arvef, in 1650.
'
Fig. 7 represents a fourth view by Helvetius, in 1650.
Fig. 8 is a most a~curate and enchanting view had by
, RiccioIi in 1651. It shows the rings of Saturn as they
are often seen in our own times, through telescopes of
moderate power. The remaining four representatioDs,
,.
j
84
TBLBSCOPIC VIEWS OF SA.TUB.~.
1
as they occur on the map, were all had in 1655: the first
by Fontani; the second by Dif1ini; the third by Riccioli;
and the fourth by GU8entlu.
The real appearance or Saturn, as seen through a
common and cheap telescope, is well represented at A or
B, immediately under the above views, with the exception
of the opening between the rings. We have often seen
nim as here represented,-and with the belts across his
disc as shown in Map 10,-and that, too, with an ordinary
refracting telescope; b~t in earlier periods in the history
of the &eience, such views were denied even to the most
wealthy. devoted, and profound astronomers.
But this wonderful planet does not present the same
appearance at all times, even with the aid or the best
glasses. Indeed, the better the instrument the more
perceptible his variations. In the course or 30 years,
the time or his periodic revol ution, he presents all the
different phases shown at Fig. 3, from A to H. At one
time the rings are entirely invisible, except 8S a dark
stripe across the body of the planet, as seen at A. A bout
years afterwards the rings appear slightly opened, as
at B; and in
years more they appear 8S at C, &c
These different phases are all accounted for by Fig. 2.
Here the sun is seen in his place in the centre, and 'the
earth and Saturn in their orbits, as they ,may be supposed
to appear to a beholder at a distance, and elevated some.
what above the plane of the ecliptic. This diagram may
be used to illustrate a variety of principles. ~
1. It shows how the axis or Saturn (88 well
hat
the earth, &c.) pre8e",e8 iU paralleli6m in all arts of ita
orbit, and from age to age.
2. It illustrates the subject of his .eal0ft8, 8S partially
explained ill Lesson 65; and shows how the sun must
shine on one side of his rings 16 years, and on the other
15 years. At A the light falls directly on the edge of
the rings; but as soon as he passes that equinoctial point,
the sun shines upon the lOfDer or 80uthem side of the rings,
and continues to tlo 80 til1 the planet reaches its other
equinox at E. Here the'light crosses over to the upper
or tIDrlA aide of the rings, upon which it continues for the
at
3t
or
~
TRLESCOPIC VlBWS OF 8A.T11B.N.
Dex~
85
15 yeaN; or till the planet pUaes round to A
again.
.
3. It shows that the Equinoze. and &laticea are by DO
means peculiar to the earth-they belong to all the planetary bodies. In the figure, A and E are the equinoctial,
and C and G the 80utitial points.
4. The learner should test himself by this figure to see
if he funy understands the subject of the "",,'a declinatWfl,
as ex plained in Lesson 48.
5. As before said, this view of Saturn in his orbit accounts for all his different phases during his periodio
journey, as shown at Fig. 3. Let the student suppose
himself on the earth, where he really is, and watching
Saturn in his course; and he will find that the rings must
necessarily present all the variety in appearance which
is seen in Fig. 3, as well as every intermediate degree of
contraction and expansion.
Let this explanation be traced through. Take any
particular position of Saturn, or take them in order, beginning at A, and it will be found that the view denoted
by the correspollding letter in Fig. 3 must be the appearance from the earth, as she comes round between
Saturn and the SUD. Ate the rings are thrown up, and
hide the upper edge of the planet; while at G they seem
inclined the other way, and the planet hides the upper
edge of the rings, &0.
6. This diagram shows why we cannot see Saturn at
all ti~in the year. Suppose him to be at C, for instance,
the first of January, and the earth on the same
aide of he orbit; of course he would be directly overhead, or rather on the meridian, at midnight, and might
thereror~ easily be seen for six hours preceding, and six
following that hour. In six monttJa from that time, or by
the first of July, the earth will have passed round to the
point opposite G; but as Saturn has moved but a short
distance apparently in his orbit, he will not only be above
the ~orizon in the daytime, but nearly in conjunction with
the SUD. He must therefore be invisible till the earth
again gets around \vhere Saturn will ~ comparatively in
opposition, or OD the dark side of the earth.
d
86
. TBLESCOPIC
VIEWS OP SA-TURK.
Lesson 66.
J)ll\IE~SION8, STRUCTURE, AND USBS OlP SATURN'S RINGI •
.
'(Map It.)
I
Diameter of the planet •
•
I)istance to the interior ring
Width ot the interior ring
•
Openi ng between the rings •
Width of the exterior ring "\
External diameter of the outer ring
Thickness of the rings •
-
•
79,000 miles•
20,000 "
20,000 "
2,000 "
10,000 "
• 192,000 "
100 "
or
«
Fig. 4 on the map is a vertical view of the rings
Saturn, or such as an observer' would have if he were
situated directly over either pole of the planet, and at a
considerable distancA from it. The opening between the
rings, and between the planet and the rings, wou Id then
be visible all round, and of uniform width. Through
these openings the stars would be as distinct as in any
other portion of the celestial sphere; hence we have
so represented in the figure.
Fig. 5 is a view of the rings as they would appear to
an observer 8ituat~d upon the body of the planet itself,
and about half way from his equator to his north pole.
This is a BUmmer view, of course, as the· rings are en.
lightened; whereas during winter in the nortbe# hemi.
sphere the rings would look dark, like the da~art of a
new moon.
Under this gorgeous arcb may be seen a portion df the
planet's surface. On the right is a MID moon, and on
the left a full moon, both in view at the same time, one in
the west and the other in the east. On the left, and
crossing the rings, may be seen the shadow of Saturn,
gradually ascending the arch as the night advances, till
it reaches the zenith at midnight, and disappears ill.· the
west at the approach of day.
'
Fig. 6 is a similar view from the body of Saturn, t.he
observer being located at a distance from the equator, or
OF DB.SCBBL AND LB VEIlJUBR.
87
near his pole on the planet's surface. The arch would
then appear low down in the south, and also more narrow
and slender; and a much 'mailer portion of the rings
would appear above the horizon. The following particulars may conclude this interesting lesson.
1. By observing the mot~on of certain spots or in.
equalities in the rings of Saturn, it has been ascertained
that they reool",e around the planet in 1OJ- hours; or in
the time of his diurnal revolution, (LesSon 21.)
2. That the rings are 801id maUer, like the body of
Saturn, seems evident from the fact that they reflect the
light of the sun very strongly, and cast a deep shadow
upon the planet's surface.
3. Stars have sometimes been seen between the inner
and outer rings, which proves them to be· actually
separated.
4. Of the tuel of these wonderful rings it is sufficient
to say that they serve as 80 many reflector, to the pl~net;
and being only about..Jt part as distant as our mOOD,
and· of such vast maguitude, they must tend grently to
modify the climate of the planet, by contributing to the
light and heat of his summer evenings. During the
winter in each hemisphere, the rings cut a ,hadotD, and
increase the intensity of the cold.
BB:aSCBEL.
U~hiS
distant orb no .spots have ever yet been discovere
. It is supposed to be surrounded by all atmosphere; bu even this is not oertain. Through a telescope .
"we see nothing but a small, round, uniformly illuminated
disc, without rings, belts, or discernible spots." It is ot
a pale Bsh color.
I.E VERRIER.
Very little is known as yet of this new member of the
solar family. We have therefore attempted no .representation of its telescopic appearance upon the map. By the
fOllowing letter, however, copied from the London '1'illle.,
.a~
88
TB1"BSCOPIC VIEWS OP LB VERRIER.
it appears that Le Verrier also may be adomed with a
suit of gorgeous rings:
STAB.nJ:LD,
Liverpool, Oct. l~, 1846.
On the 3d instant, whilst viewing this object with my
large eq uatorial, during bright moonlight, and through a
muddy and tremulous sky, I suspected the existence of a
ring round the planet; and on surveying it again for
some tilne on Saturday evening last, in the absence of the
moon, and under better, though still not very favorable
atmospherical circumstances, my susvicion was so strongly confirmed of the reality of the ring, as well as of the
existence of an accompanying 8~tellite, that I am induced
to request. you, as early as possi~le, to put the observations before the public.
,
The teleScope used is an equatorially mounted NewtoDian reflector, of 20 feet focus, and 24 inches aperture,
and the powers used were various, trom 316 to 567. At
about Bl hours, 'mean time, I observed the planet to have
apparently a very obliquely situated ring, the major axis
being seven or eight times the length of the minor, and
having a direction nearly at right angles to a paralle'l
declination. At the distance of about three diameters oC
the disc of the planet, northwards, and not. far from the
plane of the ring, but a little following it, was situate a
minute star, having every appearance of a satellite. I
observed the planet again about two hours later, and noticed the same appearances, but the altitude
declined 80 much that they were not so obvious.
impression certainly was that the supposed s
te had
somewhat approached, but I cannot positively assert it.
With respect to the existence of the ring, I am not able
absolutely to declare it, but I received 80 many impressioDs of it, always in the same form and direction, and
with all the different magni fying powers, that I feel a very
strong persuasion that nothing but a finer state of atmosphere is necessary to enable me to verify the discovery.
Of the existence of the star, having every aspect of a
satellite, there is not the shadow of a doubt. _
A fterwards I turned the telescope to the Georgium Si.
dus, and remarked that the brightest two of his satellites
or
:tD
,.
DISCOVBllY OF THE SBVBllAL PLAlfBTS.
89
were both obviously brighter than this small star aocom·
panying Le Verrier's planet.
W M. LASSBLL.
In the periodical from which we copy, this statement
of Mr. Lassell is accompanied by a drawing, representing
the appearance of the planet as above described.
Lesson 67.
OP TUB DISCOVERY OF THB SEVERAL PLANETS.
Mercury, Venus, Mar" Jupiter, and Satum, have been
known from the earliest ages in which astronomy haa
been cu,ltivated.
Vesta was discovered by Dr. Olbers, March 29th,
1807.
A,trllYJ was discovered by Mr. Encke, ot Dresden,
Dec. 15th, 1845.
Juno was discovered by Mr. Harding, Sept. 1st, 1804.
Cerea was discovered by Piazzi, at Palermo, Jan. 1st,
1801.
.
Pallu was discovered by Dr. 01 hers, of Bremen,
March 28th, 1802.
Her,chel was discovered by Sir William Herschel,
MarNj3th, 1781.
Le. Tier, the Dew planet, was dem01l8trated to eNe
~y M.
~ errier, of France, in August, 1846. Its existence and locality being thus determined, it was first
lleen Sept. 23d, 1846, by Dr. Galle, at Berlin.
As the circumstances of this discovery are oC the most
interesting char~cter, we subjoin the following letter upon
the subject Cor the perusal of the student:
EIS, near Durham, OcL 8, 1846.
But a few months have elapsed since the discovery of
.he small planet Astrma,· the companion of the small
planets JUDO, Ceres, Pallas, and Vesta, already known.
The last few days have brought us the intelligence oltha
8·
90
r
DISCOVBRY OP THB SBVBIlAL PLAKBTS.
discovery of another new planet, under circumstances 80
unexampled, as to form the most brilliant achievement ot·
theoretical and practical astronomy. Some of your read.
ers may be interested in a familiar explanation of the
steps which have led to this interesting discovery.
The motions of all the planets are affected by the gravitation of the planets to one another; and the places of the
planets in the heavens are computed beforehand, 80. that
the positions given by observation can be constantly compared with those previously calculated. Now the observed
motions of the planet Uranus, the most distant hitherto
known in our system, when thus compared, were found
not to agree with the motions which the planet would
ha ve, after allowing for the influence of all the known
planets; and when it was found that the deviations were
far greater. than any which could be ascribed to mere efrors of observation, that they were of a regular character,
and of such a nature as would arise from the action of a
still more distant planet, the attention of astronomers was
directed to ascertain whether the disturbances· were such
a.tJ to point out the position of the disturbing planet. A.
long agp as the year 1842, 8 communication took place
between Sir John Herschel and the lamented German astronomer, Bessel, on this subject: and there is reason to
suppose that some researches on the subject will be found
among Bessel's papers; for, in a letter written Nov. 14,
1842, to Sir J. Herschel, Bessel says, "In *~e to
our conversation at Collingwood, I announce t
u that
Uranus is Dot forgotten." The question w , owever,
taken up by other astronomers. Le Verrier, in France,
and Mr. Adams, of St. John's College, Cambridge, in England, each in ignorance of each otber's labors, proceeded
to investigate this most intricate question, and arrived independently at the same conclusion, that the probabl&
place of the suspected planet was about 3250 of heliocentrio longitude. This was sufficient to point out, within
certain limits, the part of the heavens at which the planet,
if visible, would be seen; and, in consequence, Professor
Challis, at Cambridge, for the last two months, was en. .
ftt~ed in mapping the neighboring stars with a view
or
---~----
-..-,
-
_.--- --
....
-- .- .......
_ .. _. -
DISCOVBllY OP THE SBVBRA.L PLANBTS.
91
detecting the planet. Sir J obn Herschel alluded to the
probability that the planet would be detected in the speech
which he made on resigning the chair at the late meeting
of the British Association. Having observed that the last
twel vemonth has given another Dew planet to our system,
he added, "It has done more. It has given us the proba.
ble prospect of the discovery of another. We see it as
Columbus. saw America from the shores of Spain. Its
movements have been felt, trembling along the far.reach.
ing line of our analysis, with a certainty hardly inferior
to that of ocular demonstration."
The eloquent and glowing anticipation of the future
was soon to receive its accomplishment. On the 31st
August, Le Verrier made public the following elements
of the orbit of the supposed planet, deduced by most
laborious calculations from the observed disturbances:
or
Semi-axis major • •
Eccentrioity • • •
Longitude of Perihelion
Mean long. Jan. 1, 1847
Periodic time • • •
Mass.
•
•
•
•
•
. • • • • •
J
36,154
0,10761
2840 45'
318 0 471'
217,387 sidereal years.
~.
He also announced that the planet would probably
present a disc of about 3/1 in magnitude. This an.
nouncement reached Dr. Galle, at "Berlin, on the 23d of
SepteMlter." and on the same evening Dr. Galle, on com.
paring" stars in Dr. Bremiker's chart with the
heavens, foft.nd a star of the eighth magnitude which was
not marked upon the map. The place of this star was
accurately ohse"ed, and on comparing this place with
its position on the following night, its motion, amounting
to about 40 ,in right ascension, and 301' in declination, was
detected; and the star was proved to be the expected
new~an~.
.
It ought to be noticed that the new investigations of Le
Verrier, accompanied with a recommendation to astronomers to search for the planet by examining whether any
8tar presented a sensible disc, did not reach Cambridge
till September 29, and that Professor Challis, on that very
92
DISCOVERY OF TBB SEVBRAL PLANBTS.
evening, singled out one star, as seeming to have a disc,
and that star was the planet. Thus the theory, derived
by a most abstruse calculation, from long-contin ued ac.
curate observation, has been cOlnpletely verified; and a
triumph has been gained which will go down to. posterity
among the most brilliant of astronomical discoveries.
The known boundaries of our planetary system have
thus been nearly doubled; a planet is added to it requiring more than 217 years to complete its revolution
round the sun; and moving in regions so remote as to
recei ve but Iiooth part of the light and heat which our
earth enjoys .
. It will remain to be discovered whether, as seems
most probable, this planet is accompanied with a train of
attendant satellites; whether its motions are in accordance with the known laws of gravitation; or whether
it, in turn, is to serve as the means of a still further extension of the sol ar system.
There is one circumstance connected with this new
planet which is too remarkable to be overlooked. It was
long since noticed by Bode, that the distance of the planets from the sun follows a peculiar law, \vhich may be
thus stated-that if the distance of Mercury from the sun
is assumed to be 4, the distance of V en us, the next planet,
.is 3 added to 4, or 7; that' of the earth" which is next,
twice 3 added to 4, or 10; and thus for the remaining
planets, the distances from each other are douhlrvery
time, as may be seen from the following tableL'
]V ame
of Planet.
DiaL from tbe SUD.
Meroury • • " •
Venus
.•
•
Earth • • • • •
Mars. . •
•
Small Planets
• •
Jupiter • •
•
Saturn
•••.
Uranus . • • •
New Planet • • •
4
7
10
16
28
52
100
196
388
Dift"ereocse.
3
8
6
12
24
48
96
192
The distance of the new planet then approximatel,.
•
OF THB SBCONDA,IlY PllNETS.
93
88.tisfies this very remarkable law; and the little stranger
is at once .recognised as bearing a strong family likeness
to the other members of our system.
TBXPLB ORBVALLIBR.
From the calculation submitted in the foregoing ac.
counts · it appears that the Le Verrier planet must be
nearly three tJamua7lll miUiou of milea trom the SIlD!
Verily, such a discovery is "enlarging the boundarie,.
the Solar System" most effectually. But what is this
distance after all, when we consider that it would re.
quire more than 6000 such journeys to reach the nearl18t
of the fixed stars ,
or
CHAPTER III.
OF THE SECONDARY PLANETS.
Lesson 6S.
CRAB.ACTBR AND NUXBER OF TRB SBCONDAR.Y PLANETS.
(Map 2.)
THE aecondary pltJnet.a are those comparatively small
bodie8~at accompany the primaries in their course, and
revolve '-lund them. As the prirnaries revolve around
the sun, so lhe secondaries revo) ve around their primaries.
• The n umber of secondary planets positi vel y known to
exist is nineteen. Of these, the Earth has one, Jupiter
ftmr, Saturn eiglaf, aDd Herschel liz. They may be
seen on the map at their relative distances from their
primaries. Their relative fIIagmJ:udu are also repra•
~
• ented.
'rhough the secondary· planets have a compound motion, and revolve both around the sun and a round their
respective primaries, they are subjeot to the same gen~ral
law8 of gravitatioD--<»f centripetal and oentrifugal lorQft
94
OF THE BARTH'S SATELLITE OR MOON.
-by which their primaries are governed. Like them,
they receive their light and heat from the SUD, and revolve periodically in their orbits, and 011 their respective
axes. In the economy of nature they seem to serve as
80 many mirror, to reflect the sun's light upon superior
worlds, when their sides are turned away from a mo...
direct illumination. The secondary planets are g~Deral11
called moo"", or 8atellika.
Lesson 69.
SUPPOSBD SATELLITE OF VBNUS.
Several astronorhers have maintained that Venul fa
attended by a satellite. From the observations of CasBini, Mr. Short, Montaigne, and otbers, as quoted by Dr.
Dick,· it seems highly prob~ble that such a body exists.
M. Lambert supposed its period to be 11 days, I) hours,
and 13 minutes; the inclination of its orbit to the ecliptic 63fo; its distance from Venus about 260,000 miles;
and its magnitude about t that of Venus. It is to be
hoped that this interesting question will ere long be fully
settled, as it is one which numerous telescopes, both in
this country and in Europe, have capacity to decide. It
is a question worthy of the attention of Lord Rosse, and
the powers of his colossal reflector.
Lesson 70.
/
OF THB BARm's SATELLITE 0& MOON.
(Map 12.)
To ordinary obser~ers of the heavens, the moon is an
Object of great interest. Her nearness to the earth-her
magnitude-her rapid angular motion eastward-her perpetual phases or changes, and the mottled appearance of'
her surface, even to the naked eye, all conspire to arrest
the attention, and to awaken inquiry. Add to this her
• Celeeti.! Scenery, pp. 84-89.
•
...,
OP THB BARTH'S SATELLITB OK KooN.
9b
conneotion with Eclipses, and her influence in the product.ion of Tides, (of both of which we shall speak hereafter
in distinct chapters,) and she opens before us one of the
most interesting fields of astronomical research.
The following table exhibits the principal statistics
and facts respecting the Dloon, and should be carefully
Bt.udied or committed to memory.
Mean distance from the earth's centre 240,000 miles.
Sidereal revolution 27* days.
Synodic revolution
29i "
13
Periodic revolutions per year, nearly Direction in orbit from west to east.
Hourly motion in orbit
- 2,300 miles.
Mean angular motioll per day
130 101' 351'1'
Diameter.
- 2,160 miles.
A pparent angular diameter
•
311' 71'1'
Bulk, as compared with the earth
•
Bulk, as compared with the sun
1'15 ,
,1r1r1
Surface, as.compared with the earth •
Density, the earth being 1
i
0
Inclination of orbit to the ecliptic
0 9'
Eccentricity of orbit
- 18,833 milel.
Longitude of ascending node
variable.
1!0
Inclination of axis to orbit
Revolution upon axis
291 days.
LIght reflected by her, as compared
·~h that of the sun
-.
3 0 I., ~ 0
4
8y c~aring the distance of the mOOD, as expressed
in the foregoing tobie, with that of the sun, (Lesson ~t)
it will be seen that the latter is four hundred times as far
off as the former. It is for this reason that she generally
appears as large as the sun, when in ract he is seventy
million times the laTgest. The moon may therefore
well be regarded as our nearest terrestrial neighbor.
It may also be interesting to compare the angular
fll4gnitude of the moon as seen from the pardi, with that
of the sun, as given in Lesson 11. They seem to differ
but D:~N; or less than one minute of a degree. Thus the
eun, on acoount of his immense distance, looks no larger
,
.1
1
j
i
96
CHA.NGES OR PHASES OF THE MOON.
than the moon 'j when in fact he is equal in bulk to
8toenty "li.llio1l8 of such bodies.
If the student does not fully understand the caae
this agreement in the apparent magnitude of the sU,n and
moon, when they are in reality so diRproportionate in
bulk, let him turn back and review LeSSon 10, and the
map and figure therein referred to.
or
Lesson 71.
CHANGES OR PHASES OF THE MOON.
(Map
12.)
The upper row of figures ,on the map represents the changes of the moon in passin"g from new to full moon,
and around to new moon again. The first figure on the
right represents the new moon, wben, if visible at all, we
see only her dark sid... She is then at her conjunction,
or in the same longituc.e with the sun, and to ordinary
observers is in visible. As she advances eastward in her
orbit, she falls behind the" sun in his apparent daily
course, and in a few days is seen in the west just after
sundown, in the form of a slender crescent, as seen in the
next view to the left. As she advances, we see more and
more of her bright side, as represented on the map, till
she reaches her t1ppOrition, when her en)~· htened hemi.
sphere is towards us, and we see her as a id~:
From this time on ward the !Deat side 0 the loon begins to be obscured, Cor want of the sun-Ii t~ an.d the
crescent begins to be inverted. From the first quarter to
the full, and from full moon to the last quarter, the moon
.
,
is said to be gibboua.
The cQ,ue of these changes is further illustrated in
Figure 2, where the earth is shown in the centre, and
the moon at various points in her orbit., The sun is
"Supposed to be on the right, as in Figure 3. The outside suit o( moons shows that in fact just one half of the
moon is always enlightened; while those on the inside
show IwtD much and which part of her enlightened aida !a
,
....
~
TO KOOK'8 P~TB ABOUND TBB 81m.
97
flUlJJle frD7A ,At. earlA. A is the new moon. B shows her
when first visible. C is the first quarter;. D gibbous; E
full mOOD; F gibbous; G last quarter; H the crelWent
inverted; and A new moon again. This revolution
the' mOOD around the earth, is called a lUfiation.
The poiJIts A and E, in the moon's orbit, are calJed
her qzggiu; C and G her quadrature.; and B, D, F,
and H, her ocIanU:
or
LeSBOD
7g.
'1'JD KOOK'S PA.TH A.ROl1ND TBB SVIf.
(Map 12.)
The revolution· or the moon around the earth, and with
the earth around tbe 8UD, is represented by Fig. S.* As
her orbit nearly coincides witb the ecliptic, she is some·
times IllitAiA, and at othel"8 fllithout the earth's orbit. When
the moon is at A, and tbe eartb in her orbit between A
and 19, it· is fttID mDmI. In about 14 days she reaches B,
and will be seen (rom the earth &8 a full ftlOOfi. In 14
days longer she reaches C, when it is new ·moon again,
, and 80 00 perpetually. At A she is in conjunction, and
at B in 0pp08ition.
But it will be seen that the twelve revolutions of the
mOOD and the one revol ution of the earth do fIOt come out
ft1eft; or in otber words, do Dot end at the same time.
From tbe new moon at A, around to the new moon at D,
are ~ twelve lunar mODths or revolutioDs; but at this
time
earth wants 19° 2(Y to reach her starting-point
• The author ill aware that the figure doee not repreeeDt the actual
path of the ~Q around the 8UD, neither i8 it pcaible to draw it, except upon a fery large &Cale. The moon ,.~~er retrogradt., but i8
advancing "i~ the earth at the rate of 65,000 miles aD bour, even
at new moo', and when falling behind the earth. When in oppoeitiol1, and pining upon the earth, her velocity .. about 71,000 miles
an hour. The true path ol the moon would appear a)mOBt pllraJlel
to that of the earth, which it would CI'088 backward and forward, at
..ery acute aarlee, every 141 day., or at iDtervale of about 1410 each.
But even the portion witli'll the earth'8. orbit would b, conca~, to.Md. tAe nn. The diagram, Fig. 3, inculcatee more tntA aJld Ie ••
.,..,.or thaD any other Wf'J could employ, aud we Ule it for the ..me
I'8UOn that we find it in Burritt'. Atl.., ad ill Mitchel'. editiOD of
1M Geopaphl of &he Ilea....
.
.
8
98
1
REVOLUTION OF THE l'tIOON'S NODES.
at A, or to complete her year. ·The lunar year, there.
fore, consisting of twelve synodical revolutions of the
mOOD, or 346 days, is 19 days shorter than the civil
year.
Lesson '2'3.
llBVOLUTION OF THB MOON'S NODES AROUND THB BCLIPTIC.
(Map 12.)
,
By referring to Lessons 30 and 31 it will be seen that
the nodes of Mercury and Venus are permanent; that is,
that they are always at the same point in t~e ecliptic, or
in the same longitude. But this is not the ol¥e with the
moon's nodes. Suppose the line passing down from A,
Fig. 3, to represent the line of her nodes, at the commencement of a lunar year. After twelve Iunations,
and when she has passed round to the point D, she will
ha ve returned to the same node again, ·although she is
19° 20' short of the point where that node was reached
846 days before. At this time the line pa.~sing down
from D would represent the line of her nodes. In this
manner the nodes of the moon's orbit fall back westward,
or recede 19-j-° every lunar year, till they complete a
backward revolution quite around the ecliptic. To do
this requires 18 years and 225 days, or 223 Iunations ;
when the moon will reaoh the same node again at D, or
in the same longitude.
~-.
This revolution of the moon's node~ will be nqticed
again in the chapter on Eclipses. The motiT of"th941prides will also be e·xplained and illustrated inlhe 5aptqr
on Tidu in connecdon with Map 14.
. ) , I ,' .
.
Lesson 74.
I.
SIDERBA.L A.ND SYNODIC REVOLUTION OP THB KOON.
(Map 12.)
The difference between a sidereal' and 6ynodic revolution of the planets is explained in Lesson 57. A 8itlet'eal
I
THE KOON'S J..IBJU.TIONS.
II
J
99
revolution or the moon is a revolution from a partio1:llar
star, around to the same star again; or what would con.
stitute a complete revolution if the earth. were at rest.
But as the earth is constantly advancing in her orbit, the
mOOD, in passing from one full moon to another, has to
perform a little more than a complete revolution to bring
her again in opposition to the sun. This extended jour.
ney is called her 8yraodiC revolution.
The sidereal period is 27} days, and the synodic 29i,
as already stated, Lesson 70.
.
Lesson 73.
REVOLUTION OF THB MOON UPON BEB. A.XIS.
"'
~.
(M~p i2.)
From the uniform appearance of the moon's surface,
even to the naked eye, it is obvious that she always presents Dearly the same side to the earth. From this fact
it is concluded that she makes but one revolution upon
ber axis during her synodic revolution-that her motion
upon her axis is from west to east-that her day (including a lunar day and night) must be equal to 29j of
our days; and that the earth is always invisible from ODe
half of the moon's 8urface.
By consulting Fig. 2, it will easily be seen that to keep
the same side towards the earth, the moon must necessarily _olve once on her axis during her synodio revolu •
.tion; and also that if the side towards the earth at the full
W8:8 t~ardl us also at new moon, the side in darkness at
full mc!oa fbUld be towards the sun, or enlightened at
new mooll~t Observe, we are speaking of her actual light
and shade, jm.d not of her appearanoe from the earth•
.
I
Lesson
'0.
THB KOON'S LIBRA-TIONS.
,
.
(Map 12.) .
Though the moon always presents nearly the same
hemisphere towards the earth, it is Dot always preci6el,
100
TBLESCOPIC VIEWS OF THE IIOON'.
the same. Owing to the ellipticity of her orbit, and the
consequADt inequality of her angular velocity, she appears to ,.,11 a }·itile 00 her axis, first one way and then
the other, thus alternately revealing and hiding ne\v ter.
ritory, as it were, on her eastern aDd westem limbs.
This rolling motion east and west IS called her lihratiOfl
in longitude.
The inclination of her axis to the ecliptic gives her
another similar apparent motion, alternately revealing
and hiding her polar regi0ft8. This is called her libratitm
in latitude. It may be illustrated by Map 4, Fig. 2, as
explained in Chapter VI.
Lesson
7'.
SEASONS OF THE KOOK.
or
The moon's year consists of 29}
our days; and
as she revolves but once 00 her axis io that time, it follows that she has but one day and one night in her whole
year. So slight is the deviation of her orbit from the
plane of the ecli ptic, and the inclination of her axis to the
. plane of her orbit, that the 8UO'S declination upon her can
never exceed 6 0 40/ • She must therefore have perpetual
winter at her poles, while at her equator her long days
are very warm, and her long nights very cold.
Lesson
'8.
,
TELESCOPIC VIEWS OF TBB KOOK.
-
(Map 1.2.)
,
Fig. 4 is a telescopic view of the moon, 88 slle apPears
when about a week old. The ragged line dividing her
ill uminated from her dark hemisphere, and extending
around the mOOD, is called the circle of illumination,. and
the portion of this circle towards the earth, as represented
on the map, is .called the Terminator. This line traverses
the moon's disc from west to east in about 15 days, when
PBYSIC~L CONSTITUTION OP TB8 MOON.
101
it disappears from her eastern limb; and the other haIr
of the circle of illumination inlmediately appears on her
western border. In about 15 days longer,' it passel
around to the eastern limb agaill, as represented at Fig.
6, and at the change of the moon entirely disappears.
The Figures 4, 5, and 6, are faithful representations
of the mOOD, as she appears through a telescope of moder- .
ate power, at three differeDt periods during a lunalion.
Lesson 79.
PHYSICAL CONSTITUTION 0 .. THE MOON-MOt1NTAI1fI, VOLCA.NOBS, ATMOSPHERB, BTO.
(Map 12.)
Nothing is more obvious, from a telescopic view of the
mOOD, than that her 8U rface is remarkably rough and u . .
~en. The evidence of this is,
Firat, the crooked aod ragged appearance of,the termifllJtor. Were the moon's surface level and smooth, thia
line would be uniform, aDd sharply defined.
In the 8econd place, small bright spots appear from
time to time, from new to full mOOD, beyond the terminator, in the dark portions of the moon's disc. These are
nevll far from the terminator, and grow larger and larger
as i~proaches them. In the same manner these bright
spots linger after the terminator, from full to De·w mOOD,
and grow ffIIlaller and smaller till they disappear.
In the ';'ird place, after these spots fall fairly within
the enJigh:ened hemisphere of the moon, they project a
.1&atlouJ towards the terminator, or in a direction opposite
to the 8U~. From new to full moon these sha~ow8 aU
point etJ8tUJard, while from full to new moon again they
all point ree#uKJrd.
N ow nothing can be more certain, from all these phe.
nomena, than that the moon is covered with mouftllJiflf.
Being elevated above the common level of the moon'.
surface, the sun's light would fall upon their summits be.
fore the 8urrounding valleys were rendered luminous or
0*
102
r·
•
PHYSICA.L CONSTITDTIOlf 01' THE lI00lf.
visible by reflected light. As the light advanced eastward it would enlarge the visible portioD8 of the moUDtaios; and finally, after the space around them, west,
Borth, and south, W88 enlightened, they would still cast
shadows eastward. Besides, these shadows are always
darkest on the side towards the SUD, or nearest the moUDtains.
By extlmining Figures 4 and 6, in connection with the
foregoing remarks, the student can hareHy fail to be satis.
fied that the moon also has her Alps, her Andes, and her
Pyrenees. Some of her mountains have been estimated
to be five miles in height.
It has been ascertained also that many of the lunar
mountains are of fJolC4Ric formation, like Etna and Vesuvius. Dr. Herschel states that he actually saw the light
of the fire. of several active volcanoes in the moon. The
extravagant statement made by some authors, that cities,
fortifiCati0n8, and rotlll8 have been seen on the moon's
disc, is worthy o.f little or no credit. It is much easier
~ imagine cities, &0., to exist on the moon's surface,
than to actually Bee them even if they were t~ere.
In regard to the existence of 8n atmosphere around the
moon, astronomers are divided. From observations during
eclipses of the sun, and other phenomena, it is thought
that if the mOOD has any atmosphere at all, it must be
very limited in extent, and far le88 deose than that ot the
earth.
t/IJ
Dr. Scoresby, of Bradford, England, has published a
description ot the moon, 88 ~he appears tarough the
monster telescope of L9rd Rosse. He repreS«¥lts her as
appearing in great magnificeoce. through this famed instrument, seeming like a globe of molten silv~r, whilst
every object or the extent of one hundred yprds was
quite visible, and edifices of the size of York Minster.
might therefore, he said, be easily perceived ~f they had
existed. He states however, that th~re was no. appearance or any t}ling of that nature, neither was there
any indications of the existence of water, nor of an atmosphere. There was a vast Dumber of distinct vol.
canoes, several miles in breadth; through one of them
..
103
GBOGUPJIY OP TO .00lf.
there was a line in continuance or ODe, about ODe hUDored and fifty miles in length, w bich ran in a straight
direction like a railway. The general appearance, how.
ever, was like one vast ruin of nature; and many of the
pieces of rook, driven out
the yolcaooea, appeared to
be l"Jd at various distances.
or
Lesson
so.
GBOGRAPHY OP THB KOON, 08 ULBKOGJU.PBY.
(Map 12.)
The great natural divisions of the moon', disc have
received appropriate names. The following is a list
8Ci)me of her principal mountaiu, and their height, according to the recent measurement
Mldler:
or
or
Peat.
.n..
Posidoniu8 • • • 19,830
8.76
Tycho • • • • 20,190
3.83
Calippus
. • • 20,300
8.86
Casatus. • • • 22,8] 0
4.32
Newton. • • • 23,830
4.52
Clavius. . • • 19,030
8.60
,Huygens • • • 18,670
8.54
Blancanus . • . 18,010
8.41
Movetus. • • • 18,440
8.49
The folfowing list may be found upon the map, Fig. Dt
the ~umbers in the drawing answering to those of the
table. It may require a Dear view to read the figures OQ
the map.
1. Tycho,
6. EratoetheDel,
2. Kepler,
7. Plato,
S. Copernicus,
8. Archimedes,
4. AristarehuI,
9. Eudoxua,
o. Helicon,
10. Aristotle.
The dusky portioDS formerly suppal8d to be- . . ., aN
clMignated 88 follows:-
•
104
A. Mare Humorum,
E. Mare Tranquilitatie,
B.
" N ubium,
F.,," Serenitatis,
C.
"Imbrium,
G . " Fecunditatis,
D.
" Neotaria,
H . " Crisium.
MM. Baal and MadIer, of Berlin, have constructed
a map of the moon, which is characterized by ProfeSsor·
Nichol of Glasgow, as "vastly more accurate than any
map of the earth we can yet produce," and 8S "the
only authentic and valuable work of the kind in existence." Fig. 0 on the map is a faithful transcript of
this invaluable drawin~ of the moon's surface.
The subject of Ecl"paea and Occultationa will be con.
sidered in Chapter IV.; and that of Title8 in Chapte~ V.
•
Lesson 81.
...
KOON8 0 .. SA.TELLITBS OF lUPIn.
(Map 2.)
I
,I
Jupiter has rour satellites, whose distances, magnitudes, and periodic times are as follows:-They are
numbered in order, beginning with the one nearest to
their primary.
Diameter in
Dlltance.
Periodic Umee.
2,500..
259,000..
1 day 18 hours.
2d
2,068..
414,000. .
3 " 1241'
3d
8,377..
647,000. .
7 " 14 cc
4th
2,890.. 1,164,000 . • 17 ". 0 "
By comparing t~e magnitule" or Jupiter's satellites,
with that of our mOOD, Lesson 70, a striking resem,blance will be discovered. Indeed the Bize and diBtance ·
of the first &Dswer almost exactly to the size an4 distance
of the moon. But when we come to the ptriodic timu,
we find a vast disproportion •. So great is the mass and
attractive (orce of Jupiter, that if even his most distant .
satellite had a periodic revolution of twenty.nine and a.
half days, its centriJ>etal would overcome its centrifuJ!'al
three, and it would Call to the body of the planet. To
balance the great aUractive foroe
the planet (Le88OD
1st
•
mil..
or
,
',.
'1
8ATBLLID8 OP SAnmK.
. 106
17) it is necP.88ary that his secondariee .hould haye a
rapid projectile motion; hence, though the first is ..
large, and as distant (rom Jupiter as our moon is from
the earth, it revolves more than fifiem tiaI. as rapidly ..
the moon. For remarks on the centripetal and centrifu.
gal forces, see Lesson 20.
, \
,The mOODS of Jupiter revolve nearly in the plane
his equator, and of course, nearly in the plane of hia
orbit and of the ecliptic. See 82 and DO. Their orbits,
as stated by Dr. Herschel, are inclined to the plane
his equator, as follow8:
,
.
1st • • • • • • . So IS' 30".
-2<1
• • • • • • Variable.
3d • • • • • • • Variable.
4th • • -. • • • • 2 0 58' 48".
The eccentriciti~s of the lit and 2d are not per.
ceptible. That of the 3d and 4th is 8mall, and va riable,
in consequence of mutual perturbations, caused by tbeir •
mutual. attraction. They all reyolve from west to east.
or in the· direction of the revolution of their prima-ry upon
his axis.
'
The satellites of Jupiter may be seen with a telescope of very moderate magnifying power, or a oommOD
spyglass; and one of them has even been seen with the
naked eye. This Doble planet with his retinue of moone
is. t~e solar system in miniature; and furnishes the moat
. glor\us confirmation of the' truth of the Copernioan
-, theory.
For eclipI68
Jupiter's satellites' see the chapter on
eclipses.
.
•
or
or
t
r
or
Lesson Sg.
SAT~LLITBS
OF SATUB.N.
,
(Map fl.)
The satellites of Sat)lrn are eight in number,· and are
seen only with telescopes of cODsiderable power. They
revol ve from west to east. The orbits of the six interior
• The eigAth baa recently been di8covered.
1(J6
SATBLLITBS 0..
S~TUaN.
satellites are MGrly circular, and very nedrly in the
plane of the rings. That of the seventh is considerably
inclined to the west, and approaches nearer to coincide
with the ecliptio. Of the new one little is known.
Their distanoes and periodic times are 88 follows:DiaL in mileL
1st
2d
3d
4th
5th
6th
7th
123,000
168,OQO
186,000
251,000
351,000
811,000
2,366,000
Periodic times.
•
•
.
•
-
o days 22 hours.
8 "
1 "
•
1 " 21 "
•
.
2
•
" 17 "
4 " 12 "
15 " 22 "
- 79 " 7 "
•
Upon this subject aD eminent astronomer remarks, that
tbe satellites of Saturn have been much less studied than
those of Jupiter. The most distant is by far the largest,
and is probably Dot much inferior to Mars in size. Ita
orbit is also materially inclined to the plane of the rings,
with which those of all the rest nearly coincide. It is the
only one of the number whose theory has been at all in.'
quired into, further than 8uffiQes to verify Kepler's law
of the period ic times, which holds good in this as in the
system of Jupiter. It exhibits, like those of Jupiter, periodic defalcations of light, which prove its revol ution on its
axis in the time of a sidereal revolution about Saturn.
The next in order, proceeding inwards, is tolerably
conspicuous; the three next very minute, and reqllA'ing
pretty powerful t~le8C0pe8 to see them; while the two
interior satellites, which just skirt the edge or. the rings,
• and move exactly in their plane, have never been discov ..
ered but with the most powerful telescopes which human
art has yet constructed, and the~ only under peculiar
circumstances. A t the time of the disappearance of the
ring (to ordinary telescopes) they have been
thread.
ing like beads the almost infinitely, thin fibre of light, to
which it is then reduced, and for a short time advancing
".
.
seen·
• By Sir William Henchel, in 1189, with • reSecting telc.cope aI
See engraving, p. 161.
IMIr feet in aperture.
SATELLITB OF LB VEl1B.IEB'S PLANBT.
107
off it at either end, speeding to return, and hasting to their
habitual concealment.*
Lesson S3. '
SATELLITES 01' HERSCHEL.
(Map 2.)
,
Herschel has .;z satellites, as shown on the map, which
revolve around him at the distances here laid down, and
in the following periodic times : Dist. in miles.
1st
2d
3d
4th
5th
6th
224,000
296,000
340,000
390,000
777,000
1,556,000
-
- - - -
Periodic times.
days 21 hours.
8 " 17 "
10 " 23 "
13 " 11 "
38 "
2 "
- 117 " 17 "
I;
- --
The satenites of Herschel are ~tillguished by two
very remarkable peculiarities. By Lesson 32 it will be
seen that his orbit very nearly coincides with the ecliptic.
Now the orbits of ~is satellites, instead of being down Deal.
the plane of the ecliptic, as is the case with those of J upiter, are elevated so as to cross it at an· angle of near 80°'.
In the second place, while every other· planet in the
Sol~ System, prim,ries as. well as seoondaries, revolves
rrollllvest to east, the satellites of Herschel have a retro.
grade or back7Dard revolution. This singular anomaly is
indicated qp the rna p by the direction of the arrow I.
The orbi:Lr of Herschel'8 mOODS appear to be nearly
circular.
,
Lesson 84.
SUPPOSED SATELLITE OP LE VERRIER'S PLANET.
From the observations of M. Lassell, as detailed on
page 88, it is not improbable that this newly discovered
• HeJ'lChel'. Treati8e.
108
••WD dD OA.llUS OF BCLIPSES:
world is attended by one or more secondary bodies. Indeed we might almost lnCer this froID analogy, especially
when we consider tbe rttagftitudc of the planet as answering pretty nearly to that of Herschel; and his immtm8e
tli8tanu from the 8UD, upOn which he also must depend
for light aDd heat. This latter circumstance alone would
seem to demand a profusion of moons to arrest the sunbeams in the surrounding space, and reflect them upon
the cold and cheerl881 bosom of their primary. For the
present, however, the learner must content himself witlt
the little we are. able to commuDicat~ upon thi~ subjeot.
in the hope that future observations may furnish U8 with
a more satisfactory knowledge of the economy and peculia rities of this tar.distant ore.
The secondary planets are all supposed to levol v~ on
their respective axes, in the time of their periodic revolu.
tions, 80 as always to present the same hemispheres to
their respective primaries. No smaller bodies have ever
been discovered revolying around the .atellite., as mOOD8
or satellites to tliem •
..
CHAPTER IV.
rmLOSOPHY OF ECLIPSES.
#"
Lesson 83•
• •",.R8 .ND CAUSBS OF ECLIPSES.
(Map 13.)
AN Eclip.e is the partial or total -ob8curalitm or darlt.
ening of either the SUD or mOOD. An eclipse ot the SUD
is caned a Solar eclipse, and that of the moon a LuRtJr
eclipse.
"To undentand the nature and philosophy eclipses, it
will be necessary to heBin with what is oalled tAe law
./aad,ow. The prinoipla. ofthia law are as follow8:-
or
oJ
109
KATURE AND CAUSBS Of BCLIPSES.
or
1. A.ltJd,ou, is a portion' of space deprived
light by
the i~terventioD of some dark or intransparent body.
2. The ltmgth and form of. shadows depend not onl,.
on the form of the opaque body, by which the light is in.
tercepted, but also upon its magnitude as compared with
the luminous body; and its distance from it. At Fig. 1
the SUD is seen at S, on the right, the earth at B, and
tbe moon at A and C. The shadows of the earth and
moon are seen projecting to the left, and running to a
point. They have this form because the earth and moon
are 8fIItl1le,. than the 8un; and as the earth is a globe, her,
.hadow assumes the form of a cone, with its base towards
the sun.
3. If the earth were jut as large as the sun, her shadow
would be in the form of a cylin'der J. and if larger than the
.un, it would spread out like a fan; or like the section or
a cone with its base turned from the sun. These principles may be illustrated at leisure by a candle and several
balls of different sizes.
4. When the opaque body is amo11er than the luminous
one, the length of its conical shadow will depend upon ita
distanoe from the ,source of'liaht. Thus, if the earth were
at E, Fig. 1, her 'shadow would be shorter than represented in the figure, by one half.
~. The shadow cast by the earth is darker in some
patts than in others.' This is represented at 0, and P P,
F~ 2. The deep conical shadow shown at 0, and in
a1tlae other figures, is called the Umbra; and the faint
.&hadow shown at P P, the Penumbra.
We are.now prepared to state the cafUel or eclipses:
1. .An Eclip6e oj- the BU1I is caused by ,the moon passing
between the earth and the sun, and cRsting her shadow
upon the earth.' This is represented at A, B, Fig. 1, .
where the moon is seen passing in her orbit around the
earth, and hiding part ot" the sun's disc at S, from the ob.
aerver at B; or, what is the same thing, casting her
.hadow upon the earth at B. As the moon is moving
eaatward, or in the direction of the arrows, she covers the
lower
tD8Item limb
the sun first, and advances to the
eut. By turning the right side of the map uppermost {or
10
or
or
110
CHARACTER, ETC., OF SOLA.R BCLIPSBS •
.
a momPDt, and placing it to the south of the learner, the
figure. can hardly fail to give l)im a correot idea or the
manner in which a solar eclipse is produced, and the
reason why it always commences OD the sun's western
limb.
2. Eclip,e8 cif tlte moon are caused by her railing into
the eart1&'. shadow, as represented at C. Th~se always
commence on the moon's eutem limb, as may be shown
by turning the left side of the map uppermost.
8. In its natural position the map illustrates another
fact: it shows why eclipses of the sun always happen at
ftefD mOOD, and eclipses of the moon at full mOOD.
To
an observer on the .earth the moon must be ReID at A, and
full at C.
·
Lesson S6.
CHARACTER, EXTENT, AND DUllA.TION OF SOLAR ECLIPSBS.
(Map 13.)
1. The first thing to be determined in regard to solar
eclipses is the length of the moon's shadow.;. Let the student now call to mind the 'fact that the earth and InDOD
both move in elliptical orbits, as stated in Lessons 43, '5,
and 70. Let him remember also, that the sun is in doe
of the foci of the earth's orbit, as represented in Fig. e :
and that the earth is in one of the foci of the moon'8 ~£jt.
a8 shown at T and U. Now as the earth is farther..Pom
the sun at U than at' T, her shadow will be longer; and
80 with the moon.
The shadows of both are much longer
when the earth is at or near her aphelion, as at U, then
when near her perihelion, as at T.
2. The length of the moon's shadow is also modified
by her position in her orbit. As her mean distance from
the earth's centre is 240,000 miles, she must be 480,000
miles nearer the sun at new moon, than at her full. This
difference in her distance must haveits effect in lengthening or shortening her shadow. At T, Fig. 2, the earth
is at her perihelion, _nd her shadow and that or her aatel..
lite are comparatively short. At U the earth is at her
J'
- ---
-
CHA.RACTER, BTC.J OP SOLAJ1 BCLIPSBS.
III
most distant point from the sun; and the shadows of both
the earth and the moon are proportionally elongated.
3. A third circumstance modifying the length ot the
moon's shadow, is the position or Aer apAeliOft and periMlion points, in respect to the SUD. When the earth is at
T, in her orbit, and the moon at her aphelion at M, whioh
is then t,otDQ,rtl8 the 8un, her shadow is the shortest possible; as she is then ft&Jrtr the aun than at any other
time; but when the earth is at her aphelion at U, and
the moon comes to her aphelion when it. is turned from
the sun as at K, her shadow has its greate.t possible
length. Such is the variety or causes whioh conspire to
afFeot the length of the shadows projected by the earth
and moon.
4. When the earth is at U, and the moon at her perihelion, and in conjunction as at H, her shadow will exteqd 19,000 miles beyond the earth; and 'Will be nearly
175 miles in diameter at the distance of the earth's sur.
face. Consequently if her shadow fall. centrally upon the
earth, it will cover an area 175 miles in diameter, within
which the sun will appear totally eclipsed. At this time
the ptmumbra will cover,an area 5,000 miles in diameter,
w" in which the eclipse will be only partial. It the
8
dow falls upon the ride of the earth, it will or course
o er a much larger space; and in either case, it will
m e from west to east over the earth's surface.
When the earth is at T, and the moon at M, the
aha ow ot the moon will not reaoh the earth by 20,000·
miles; and when the SUD and moon are at their 'mean
distances -from the earth, the cone of the moon's shadow
will terminate a little before it reaches Ute earth's surface.
6. The angular or apparent magnitude of a body depends much upon its distance from the observer, (Les80'0 10.) When the sun and moon are at their mean
distances, they appear nearly ot a si~e; but when the
earth is at U, and the moon at H, the moon appears
larger than the SUD, and if a central eclipse take place,
it will be total; or, in other words, the moon will en.
tirely cover or hide the sun'a race. This is owing to the
,
112
CIUJU.CTEa, BTC., OF SOLAa BCLIPSBS.
or
or
nearness
the moon to the eartll, and the distance
the sun. A total eclipse may last 7 minutes and 58
seconds.
7. When the earth is at T, aDd the moon at M, the
IUD, being at his perihelion distance, will appear Ufl1U1IalI, large j and the' moon being in apogee, will appear unfUU,Q,lly amall. Should. a oeotml eclipse happen at. this
time, the moon would Dot be Jarge enough to hide the en.
tire face of the 8UD, evelJ when '<lirectly between us and
him; coDsequently in the middle of the ecUpse the mOOD
would be seen covering the centre of the 8UD, and lea villg
a luminous ring unobscured, as represented at V on the
map. This is ca.lled an QllAular eclipse; and the ring
may last 12 minutes and 24 seconds.
8. For convenience in describing eclipses, the diameter
of the sun and moon, respecti\rely, is divided ioto twelve
parts called. digi,tB. Thus at W, the sun would be delCribed as about three digits eclipsed j at S, about four
d~i~&c.
.
The learner will now understand the difference between
partial and total, eentral and annular eclipses. Both anDu]ar aod total eclipses must be central, but the annular
eclipse is not total. The ring or outer border of the
is left uoobscured.
_
"The following is a list of all the solar eclipses
t
will be visible in Europe and America during the e.
mainder of the present century. To those which ill
be visible in New England .Ute number of digits is an·
nexed.
'flO
jf
Y88I'.
1847,
1848,
1851,
1854,
1858,
1859;
1860,
Kon&b.
Oct.
Mar.
July
. May
Mar.
July
July
DiaitL
Day aDd Hour.
9
1
o A.. x.
5 7 .50
28 7 48
26
4 26
15 6 14
82
29
I)
18
7 23
A..
A..
P.
A.
P.
A...
It.
M.
M.
K.
x.
x.
6t
8t
lit
It
2i
81-
....
113
CHARACTER, ETC., OF SOLAR BCLIPSBS.
Year.
Month.
1861,
1863,
1866,
1866,
1867,
1868,
1869.
1870,
1873,
1874,
1875,
1876,
1878,
1879,
1880,
1882,
1885,
1886,
Dec.
May
Oct.
Dot.
Mar.
Feb.
Aug.
Dec.
May
Oct.
Sept.
Mar.
July
July
Dec.
May
Mar.
Aug.
Aug.
June
June
Oct.
Mar.
Aug.
July
f!.87,
890,
891,
,
1 892
t:m·
96,
1897, .
1899,
1900,
•
June
May
Da, aad Hour.
31 7
17 1
19 9
S 11
a 3
23 10
7 6
22 6
26 3
10 4
29 5
25 4
29 4
19 2
31 7
17 1
16 o
29 6
18 10
17 3
60
20 o
26 4
9 0
29 9
8 0
28 8
or
DIIItL
80
A.. K.
P. K.
4j
10
12
A... x.
A... K.
A... K.
A.. x.
A.. K.
A.. x.
8f
o
o
o
21
o
o A. M •.
o A. K.
56
11
56
101
A.. K.
IIi
P. Ji.
P. M.
A.. M.
A.. M.
3f
71
o
30
o A.. M.
35
30
0
A.. M.
A.
P. K.
A.. M.
x.
o
o
o Mer.
19 P. x.
o A.. M.
ot
6i
01
8!
o Mer.
A..
x.
9 A,
x.
8
o Mer.
'i
11
The eclipses
1864, 1869, 1876, an.d 1900, will be
very large. In those of 1858, 1861, 1873, 1875, and
1880, the .fUR tDill rile eclipletl.
Those of 1854, and 1875, will be annular. The
aoholar can continue this table, or extend it backwards,
by adding or subtracting the Chaldeao period of 18 yean.
11 day., '7 hours, 54 minutes, and 31 seconds.·!'
• Ferg.oa.
8*
114
ZCLIPUS 01' THE KOON.
Lesson 87.
BCLIPSBS OP THB llOON.
I'
(Map 13.)
1~ The average length of the earth's shadow is 860,000
miles; or more than three times the moon's average distanoe from the earth. Its average breadth at the distance
of 240,000 miles'· (rom the earth's centre, or where the
moon p8.88e8 it, is about 6,OO~ iniles; or three times the
moon's diameter. Now the exte~ and duration of a lunar
eclipse must depend upon these three circumstances:
(1.) The distance of the eartA from the auft, and the
oonsequent length of her shadow at the time.·
(2.) The distance of the ~Oft from the earth, which
determines the diameter of the earth's shadow where the
mOOD passes it; and
(3_) The manner in which she passes through the
earth 8 shadow .. If it be greatly elongated, it will be
proportionably larger at the average distance of the moon's
orbit; and if the moon is in perigee, tlnd passes central',
through the earth's shadow, as at G and X, Fig. the
eclipse will be total, and long continued. On the ther
hand, if the moon is in apogee, she will pass the e rth'a
shadow where it is comparatively slender, as at ! and
the eclipse will be of comparatively short duration.
So if she pass through the aide of the shadow, instead
its centre, the eclipse will be partial instead of total.
An eclipse of the moon c~n Dev~r be anntllar, as she
cannot get 80 Car ofFthat the earth's shadow would be iDe
sufficient, when centrally passed, to cover the whole
the moon's disc.
2. Before the moon enters the earth's shadow or umbra, as at 0, the earth begins to interoept from her portions of the sun's light, or to cast a faint shadow upon
her. This shadow, called the moon's penumbra, grows
darker and darker as ahe advances, till she enters the
conicnl and perfect shadow of the earth. Here tbe real
eclipse begins. The umbra and penumbra may be IIeeIl
i-t 0, and P P, on the map.
or
or
TIll. A.ND FaXQl1ENCY OF ECLIPSES.
LeS801
J16
SSe
OF THE TIME A.ND FREQUENCY or ECLIPSES.
(Map
13.)
1. If the moon'. orbit lay in the plane or the ecliptic,
as represented at Fig. 1, there would be two celltral
eclipses every month j viz., one of the sun and one or
the mOOD. But as the moon's orbit is inclined to the
ecliptic at an angle of 50 9', (Lesson 70,) it is evident
that she may be either Q,lHme or 6eloJD the ecliptic at the
time of her conj unction w\th the sun; 80 that she will
seem to pass either aiHme or belOUJ him, and will not
cause an eclipse. This will be understood by oare fully •
observing the moon's orbit at M and H, Fig. 2. At M,
the side towards the sun appears t,hroum, up or ab~e the
ecliptic; while at H it is hew., the ecliptic. Of course,
then, the mooD's .laadouJ wUl pass belOUJ the earth, as
represented at H; and though it be ever so long, there
"il~ be no eo~ipse. For the same reason, the moon may
either above or below the earth's shadow, at the
· e of her opporititm, and no lunar eclipse occur.
• It is only when the moon is at or near one' of her
., that either a solar or lunar eolipse can occur.
o the Map; Fig. 2, the line L N represents the line of
the nod~ 88 well 88 the plane olthe ecliptic. At A, the
, moon is seen coming to her node, in the direction of the
arrow, and castiog her shadow upon the earth. At the
same time we see the e.clipse advancing in the same·
direction, commencing upon- the sun's western limb at
W. At G ud X, in the same figure, we see the moon
totally eclipsed. If, therefore, the earth and the mOOD
reach the line. of the moon's· nodes at the same time, the
eclipse will be central, whether it be of the 8un or
moon.
3. But it is not necessary that the earth and mOOD
Ihould be precilel, on the line of the moon'. nodes, in
order to produce an eclipse. U The distance of the
mooD from her node when she just touches the shadow
116
TIll. AlfD PJ1BQl1ENCY
or
ECLIPSES.
or
the earth, in a lunar eclipse, is called the La...
Ecliptic Limit; and her distance from the node in a solar
eclipse, when the moon just touches the solar disc,
called the Solar Ecliptic Limit. The Limits are respectively the farthest possible distances from the node at
which eclipses can take place."·
,
The LUfI4r Ecliptic Limit is 11 0 25' 40". This is the
greatest distance from the moon'l node at which a lunar
eclipSe can take place; and in the even" of its happening
at such a distance from the node, it must be exceedingly
.mall or slight.
The SolQ,r Ecliptic Limit is 160 59'. If at the moment
at Dew moon her node be more than this distance from
the sun, no eclipse can happen.
1'his subject may be elucidated by contemplating the
moon as seen in her orbit at A, Fig. 2. As she approaohes her Dode, it is evident that she will overlap or
eclipse the lun, as soon as she gets within haIr the sun'.
diameter of the ecliptic; as just one-half of the sun is
above the ecliptic. That point, therefore, in the moon'.
orbit which is only the semi.diameter or both the sun and
moon from the eoliptic, is the ecliptic lim';' for
r
eclipses.
.
4. The moon's nodes oonstantly
back westw
OIl the ecliptic, at the rate of about 1 go per year; 80 .~t
she comes to the same node again, as (rom the line mA, Fig. 2, around to A again, in 19 days less than a
year; or in 346 days. In just half this time, viz. 178
days, she passes her otber node in the opposite Mide or the
ecliptic, as at N. It follows, therefore, that at whatever
time of the year we have eclipses at either node, we may
be sure that in 173 days afterwards we shall have eclipses
at the otber node. And as (or any given year eclipses
commonly happen in two opposite months, as January
and July, February and August, May and November,
these opposite months, whichever they may be, are called
fOr that year the Node Montu;'
1;. There cannot be leas than two nor more thao eevea
u.
ran
• Ol_ad.
BCLIP8D, Oil OCCULTA.TlOBS 01' TIIB 8TA.IlS.
]
17
eclipses in ODe year. If but two, they will both be of the
IIOD; but if seveD, five will be of the Bun and two or the
mOOD. The usual number is two IOlar and two lunar.
Lesson 89.
BCLIP8BS, OR OCCULTA.TIONS OP TIm STDS.
The occultation ot a star is caused by the moon'.
passing between us and it, and concealing it from our
yiew. Though a very simple and common phenomenon,
it is, nevertheless, a very interesting one. At New
MOOD, especially, the star occulted may be traced to the
very border of the moon's eastern limb, when it suddenly
goes out. From these stellar occultations, or eclipses
the stars, many important conclusions may be drawn.
They teach us that the moon is an opaque body, ter.
minated by.a real and sharply defined surface, intercepting .light like a solid.
.
They prove to U8, that at those times when we cannot
Me the moon, she really exists, and .pursues her course ;
and that when we see her only as a crescent, however
, the whole globular bod y ia there, filling up the
ent outline, though unseen. For ocoultations take
indifferently at the dark and bright, the visible and
mVl
Ie ouiline, whichever happens to be towards· the.
dire on in which the moon is moving; with this only
difference, that a star occulted, by the bright limb, if the
phenolDenon be watched with a telescope, gives nbtioe,
by its graddal approach to the visible edge, when to expect its disappearance; white, if occulted at the dark
limb, if the mOOD, at least, be more than a few days old,
it is, as it were, extinguished in mid-air, without notice
or visible cause for its disappearance, which, 88 it happen.
",.tanta'M0U8ig, and without the slightest previous diminLltion of its light, is always surprising; and, if the star
be a large and bright one, even startling from its suddenness. The reappearance of a star, too, wheJ;l the moon
has passed over it, takes place, in those cases when the
bright aide of the moon is foremost, DOt at the concave
or
118
BCLIPSBI 01' JUPITER'8 MOONS.
or
'I1tline of the orescent, but at the invisible outline
the
)omplete circle, aDd is 8Ca~ely le88 surprising (rom ita
iuddeDDe&8, than its disappearance in the other case.·
Lesson 90.
BCLIPSBS OP 1l1PITBJ1'S MOONS.
Every planet in the Solar System, whether primary
or secondary, casts its shadow in the direction opposite to
the $un. But none of the primaries can eclipse each
other. In every case, however, where they are attended
by satellites, there may be eclipses.
Of the number, distance., magnitudu, and motitmB of
Jupiter's moons, we have already spoken in Lesson Sl.
It remains DOW to consider their eclipsu.
From th~ magnitude of Jupiter, and his distance from
the sun, it will be seen at once that he must cast a
shadow of great dirnensioDs, extending far into space to.
wards the orbit of Saturn. But in order fully to under.
stand the subject of his eclipses, it ,viII be necessary to
take into the .account not only his distance, magnitude,
&0., but the near coincidence of his orbit with the ec "tJtic,
his equator with his orhit, and the orbits of his moons ith
his equator. All these points will be found duly no L)ed
under their 8 ppropriate heads in the preceding Ie
•
Let it be remembered then.,
1. That Jupiter casts a broad and long shadow i • the
direction opposite the sun.
2. That the centre of this shadow lies in the plane
his orbit, which differs only 1!-0 from the plane of the
ecliptic. (32.)
.
3. That his axis is inclined to his orbit only 80 5', and
or course the plane of his equator nearly coincides with
that of his orbit. (50.)
4. Three of his moons revolve very nearly in the
plane of his equator, and' must consequently pass near
.tie centre of his shadow at every revolution. They
must., therefore, be totally eclipsed.
or
• Henchel'. AIIronomy
,
..
ECLIPSBS OP SATURN AND BBR8CBBL.
119
5. The most distant of his satellites haa an orbit more
inclined to the ecliptic, 80 that she IOmetimes but just
grazes the border of the shadow in passing, aQd some.
times wholly escapes. But these instances are comparatively rare. As a general rule, it may be said that the
satellites or Jupiter are totally eclip,ed at Imery rlmolution ;
so that by determining the number of revolutions each
makes in a month, (81,) and adding them together, we
find the number of eclipses in that period of time. They
amount to about forty.
6. FroIn the marne,. of his satellites (Lesson 81) we
infer that they must pass his shadow where its diameter
must be nearly as great as that of Jupiter; hence the
eclipses are usually total, an. last for some time.
7. The ,hadolD. of the satellites, being much longer
than those of our moon, on account of their greater distance Crom the sun, and the neamess of the satellites to
Jupiter, are cast upon Aim at every revolution. They
may be seen with good telescopes" like small round ink
.pot8~' traversing his disc.
'
8. The entrance of Jupiter's moons into his shadow is
called their immerBion; and their egress therefrom their
emer,· • Tables have been constructed showing the pr••
ei8e ',' 11&8 when these shall take place, for a given longi.
tud
n the earth, as, for instance, Greenwioh Observatory whioh tables are employed, in connection with a
cA~
fer or accurate timepiece, for determining terrestrial ongitude.
•
LeS80191 •
ECLIPSES OP SATURN AND HERSCHBI..
or the satellites of these two planets, too little is known
to admit oC any very positive statements in respect to their
eclipses. Indeed very little is said upon this subject, even
by the ablest practical astronomers. Of Saturn it is remarked by Dr. Herschel, that owing to the obliquity of
his rings, and of the orbits of hiS satellites to the ecliptic,
-they Buffer no eolipses, the interior ones excepted, uatil
•
120
NATt7KB .llfD CAUSES
or
TIDBS.
Dear the time when the rings.are seen edgeuMe. (See
Leason 66, and Map.)
or the eclipses of Hersohel's mOODS, nothing whatever
Is known by observation, and very little by theory, 88
deduced from their distances, inclination
orbits,
&0.
.
.
or
CHAPTER V.
PHILOSOPHY OF THE TIDES.
Lesson 9~.
I
KATURE AND CAUSES OP TIDBS.
(Map 14.)
THB alternate rising and falling of the waters 0 r the
ocean are called Tides. The rising of the waters is called
Flood tide, and their falling Ebb tide. There are two
flood and two ebb tides every day.
The caUBe of the tides is the attraction of the SUD and
moon upon the earth and the waters surrounding i
Fig. 1 represents the earth surrounded by wate ~D a
Itate or reet, or as it would be were it .no~ acted up ~ by
the sun and mOOD •
. Fig. 2 shows the moop at a distance above the !a~h,
and attracting the waters of the ocean 80 as to p. uce a
high tide at B. But as the mOOD makes her apparent
westward revolution around the earth but t.)nce a day,
the simple raising of a flood tide on the side of the earth
towards the moon,. would give us but one flood and one
ebb tide in twenty.four hours; whereas it is known that
we have two of each.
Fig. 8, therefore, is a more oorreot representation of
the tide. wave, as it actually exists, except that its height,
88 compared with the magnitude of the earth, is vastly
too great. It is designedly exaggerated, to illultrate the
principle under consideration. While the moon at A
produoea a big~ tide at B, we see a high tide at-,C, on the
NATURE AND CAUSES
~
.
,.
or
..
121
opposite side of the earth. Of course it is low tide, at
this time, at D and E; and as these four tides, viz. two
high and two low, traverse the globe from east to lVest
every day, it accounts for both the ,rising and falling or
the tides every twelve bourse
But the most difficult point remains yet to be elucidated.
"The tides," says ,Dr. Herschel, "are a subject on which
many persons find a strange difficulty of conception. That
the moon, by. her attraction, should heap up the waters .
of the ocean under her, seems to most pel'8ODS very nat..
ural. That the same cause should, at the same time,
heap them up on the opposite side of the earth, [8S at C,
Fig. 3,] seems to many palpably absurd. Yet nothi~g i.
more true, nor indeed more evident, when we consider
that it is not by her !Doole attraction, but by the differencu
of her attractions at the two surfaces and at the centre,
that the waters are raised."~
, The law of gravitatio~ (17) is the same which prevails
in the diffusion of light, (12,) namely, that its force ia
.fJer8ely Q,8 the 8quare8 of the diatancea; or, in other
words, as the squar~ of the distance is diminished, the
force of attraction is increased, and ",ice 'Der8d. Let this
rul~ be applied to the earth and moon, Fig. 3.
t In the first place, nothing can be more evident thaa
tJ»' the tide-water at B is the whole diameter of the
ea:. ,or 8,000 miles near.er the mOOD at A than tbe
wai r8 of the opposite side of the earth at C. They
must also be 4,000 miles nearer than the centre of the
earth, or the parts between D and E; while these parts,
turn, are· 4,000 miles nearer than the waters at C.
2. Now as the force of ~e moon's attraction depends
upon her distance, it must follow, in the second place,
that the different parts of the eartb will be uneq1J.ally attrfU!ted. B will be attracted more than D E, and D E
more than C •
. 8. This unequal attraction of the different parts of the
earth's surface will tend to 8eparate these parts. As B
is more strongly attracted than the body of the earth, it
in
..
TIDES.
• Treatille, 315.
11
122
LAGGING OF TIlE TmE, ETC.
will be drawn farther towards the mOOD, 80 as to produce
a high tide on that side of the earth. The body, or solid
parts of the earth, being nearer to the moon than the
waters at C, will also recede from them towards the moon,
causing the waters of the other side of the earth to tend
(rom D E towards C, and raising a high tide at that point.
4. This perturbation, or swinging of the earth one
way and the other, in her orbit, is assumed to be a CODstant result of the moon's attraction. Though the earth
never deviates from her course more than the amount o(
her diameter, yet this is considered sufficient to account
(or the high tides opposite the mOOD, when in conjunctiOD
with the SUD, upon the principles already explained. For
a Dew theory of tides, see Lesson 94.
Lesson 93.
LA.GGING OF THE TIDE-EXCURSIONS IK LATITtTDB.
(Map 14.)
1. The vertex, or highest point of the tide. wave, is
generally about three hours behind the moon in her
sage westward. This is illustrated at Fig. 4, wher
moon \ is seen on the meridian at A,. and the tide.
hanging back to the east, with its vertex at B.
tide will be rising at C when the moon passes the
·d.
ian; and will continue to rise for three hours afterwards,
when it will reach its highest point, and begin to ebb
again.
•
The cave of this delay of the tide. wave is a want of
time {or the waters of the ocean to yield to the impulse
given to them by the moon's attraction. Besides, as the
moon continues to act upon the waters east of her meridian, for some time after she has passed over them, it is
natural that they should still oontinue to rise.
2. Not oDly does the tide lag behind the moon, but
the moon lags behind her hour, 80 to speak, or rises later
and later every night, as she advances eastward in let'
orbit; so that high or low water is about fifty minutel
I
·1
IPKllfG AND NBAP TIDBI.
123
Jater every day, in reaohing any particular meridian, than
00 the day preceding.
8. The position of the moon in regard to the equinocUo,l has also its effect in modifying the tides. This is
illustrated at Fig. 5, where the moon is seen at A, Bout"
of the equinoctial, and the vertex of the tide. wa ve at B,
on the Tropic of Capricorn. Of coul"8e the vertex of the
opposite wave would be at E, in the nortkem hemisphere.
Were the moon at C, or north of the equator, the vertices
of the wave would be shifted from Band E to D and F.
It is in this way that the declinatiOA of the sun and moon
( 47) materially affects the tides in any particular latitude.
As the vertex of the tide-,,·ave tends to place itself verti.
cally uad~r the luminary which produces it, when this
vertical Qhanges jts poin~ of incidence on the surface, the
tide.wave must tend·to shift accordingly; and thus, by
monthly and annual periods, must tend to increase and
diminish alternately the ptiRcipal tides. The period
the moon's nodes is thus introduced into this subject;
her excursions in declination in -one part of that period
being 290, and in another only 17G ,:on either side of the&.
equator.·
.
is on this aocount, that in high latitudes 'e~ery al.
tel ate tide is higher than the intermediate ones,.. the
e~ ing tides in summer exceeding the morning tides,
ali·, tbe morning tides in winter exoeeding those of the
I
or
e'Yelling.
Lesson 94.
8PB.DfG Am)" NEAP TIDES.
(Map 14.)
I
or
1. We have hitherto spoken chiefly
the" moon as in.
strumental in the production of the tides. But though
ahe is the priMipal, she is not the only cause. The mass
.of the SUD is seventy millions times greater th an that
of the moon, (70,) but in consequenoe of his great di8tanu,
or
• Benchel'. Treatile, 317, 318.
124
IPalKQ AND NLlP TIDES.
his influenoe upon the earth in the productioD of tides i.
only about one.third as great as that of the moon. Still it is
amply sufficient to produce a perceptible tide-wave of
self, independently of the aid of the moon. Now as the
solar and lunar influences are to each other as one to
tlree, it is evident that when the two forces are combined
they will p'roduce tides one.third hig1aer than usual; and
when they counteract each other, the lunar tide-wave
will prevail, but will be one·third lower than usual.
These extraordinary variations are called the Spring and
Neap tides. There are two of each every month. The
.pring, or highest tides, occur at the ayzygie8, or at new
and full mOOD, and the neap tides at her quadratures.
A, B, C, F, Fig. 6, are intended to illustrate theae
phenomena. At A, the moon is seen in eonjuftction. It
is now new moon, and the sun and moon act together
upon the waters of the ocean, producing a Spring'ti.tk.
The map shows the tide.wave as considerably higher
than at F or B.
2. At B, the moon has passed to hel' fir" quarur, so
that her attraction is in a direction at ri$ht angles with
that of the sun. But as she exerts three1°urt.1uJ of all the
attracti ve force of the sun and moon both, she succ de
in producing a lunar tide in apiJe of the BUn, thoug
.
IJUbtraots one.third from what would otherwise be
elevation. On these principles we account for the
i'-
~8.
•
.
8. At C, the sun and m90n are seen in oppoaition, and
the earth exhibits another qring tide. But here it is evi.
dent that the tide.wave opposite toeaoh lumintry respeotiv~ly, cannot be materially augmented by the perturbations' of the body of the earth, as illustrated at Fig. 8,
and explained at the beginning of this chapter: (or as the
sun and moon act in direct opposition to each other, they
tend to keep the earth from swinging towards either. But
as the moon exerts three times the force of the BUD u~
the earth, she will attract the earth towards her, in spite
of the sun; 80 that she will thus contribute to the pNd uction of the tide-wave 00 the side of the earth towarda
C. On the hemi2tphere t.orDard. the moon, she must raiae
8PJlUtG AltD NEAP TIDK!.
125
or
her own tide, and that, too, with the whole (orce
the
8un's attraction acting against ber. How, then, is the
spring tide produced at this time on the side of the earth
opposite the SUD 7 And yet such is the fact.
Here is a point which it must be acknowledged is not
aatisfactorilyexplained by the prevailing theory of tides.
When the sun and moon are in oppoBititm, they must
necessarily dimlniaA that perturbation of the earth, which
is assumed to be the cause of spring tides, and as the
cause is reduced, the effect also should be reduced. Ac.
co~ding to this theory, therefore, we ought to have a ""1'
instead of a ayring tide, w ben the SUD and mOOD are in
opposition. The earth cannot swing in two opposite di.
rections at the same time. Even Prof. O~msted, whose
abilities as an astronomer and mathematician are univer.
sally acknowledged, seems to be at a loss here. He
says :-" At the time of new moon, the sun and moon
both beiD~ on the same side of the earth, [u represented
at A and n,l and .acting upon it in the same line, their
actions conspire, and the sun may be considered 88 add..
ing so much to the force of the mOOD. We have already
exp ·oed how the moon contributi\8 to raise a tide on the
OPI ite side of the earth. But the sun, as well as the
. mo ,raises its own tide-wave, which, at new mOOD, co.
inc es with the lunar wave. At full moon, also, the
two ·lumiDari~ conspire in the same way to raise the
tide; for we must recolleot, that eaoh body contribute.
to r~ise the tide on the opposite side of the earth, a8 well
as OD the siJie nearest to it. At both tbe conjunctions and
oppositions, therefore, that is, at ~he ,yzygie8, we have
~DU8ually high tides."*
.
Here it will be seen that the learned author speak.
of the fact of spring tide at full moon, and refers to t)ae
general prinoiples upon whioh we aocount for spring tide
at netD moon; but 10tD the sun and mOOD, acting in oppo..
can ·produce spring tides, remaiDs yet to be explained.
4. At F, we see the moon in the neighborhood of her
.u.um,
• IntrocluotioD to AItroaomy. 168.
11*
11 ..
..
126
PROFESSOR DAVIKS' THEORY.
.l4at quarter, and the earth exhibiting the neap tidu
again. We have thus passed through with one lunation,
in which we have at A· and a, tlDO qring tide., and a1
Band F t'IDO neap tides.
The spring tides are not at their height at the m0ment of the syzygies, but about thirty.six hours atiel\.
wards.
PROFESSOR DA. VIES' THEORY.
Since the foregoing was in type, the author accidentally met with Prof. Davies, formerly of West Point, woo
in view of the exceptions we had taken to the prevailing
philosophy, on the preceding page, submitted the follow.
109 theory. So far as we can discover, it is a philosophical one, and it is certainly more satisfactory u pan
1001e points than the prevailing doctrine, which we had
previously ventured to call in q~estion. In the correctDess of his theory, Prof. D. expresses entire confidence;
and by his consent it is here inse_rted for the benefit ol
the reader.
The principle upon which he accounts for the tidee.
is that of Aydt08tatic pressure. When Ouids of di . ent
apecific gra vity are mingled together, the hea vie
ill
displace the lighter, and cause them to rise to the suO
If the waters of the ocean were not acted upon b
IUD or moon, their specific gra vity would be the arne
all over the world;· and they would consequently balanoe
each other, producing equilibrium, as represented at Fig.
1. But the sun and moon do attract the waters of the
ocean, and destroy their equilibrium. Take the earth
and mooq 88 represented at Fig. 3. While the moon is
at A, the tendency of ber attraction is to diminish the
8peoifio gravity or weight of the waters at B, as she over.
comes a portion of the earth's gravitating force; so that
these waters become lighter than they are wont to be.
At the same time the moon acts upon the waters at D E
with a slightly diminished force; but the tendency at
these points is in a Aoriumtal direction, or from D E
towards A, and not away from the earth's centre. ()t
course, then, the specifio gravity
the water is DOl
or
OTua IKBQ17ALITIBS OF TBB TIDES.
127
ZU.ened at D and E, but rather increaeci. But as the
waters. at B are rendered lighter by the moon's attraction, the waters at D E, having retained their uaua)
weight, at least, will displace the former, thus causing
the waters to ran at D and E, and rise at Band C. In a
word, the difference in the direction·of the moon's attraction. at Band D E, as respects a perpendicular to the
earth's centre, makes a difference in the tDeigA' of the
waters at these two points; and the waters at DE', being
1&eamut, sink down till the lighter waters at Band C
are increased enough in tIuantity to balance them; or
till eq uili bri um is prod uced.
.
, This theory applies as well to spring tides at rull
moon as to any other tides; and besides, it requires DO
sensible perturbations of the earth as' the result of the
moon's attraction. It is, therefore, preferable to the com.
mon theory laid down by authors, and is commended to
the student as decidedly the beat method of accounting for
the production of Tides.
Lesson 93.
OO:UBR
.(
~NEQUALITIES
OF TUB TIDBS.
(Map 14.)
1. The tides vary in height, according to the dJltaneu
the earth and moon at the time when they occur.
Take, ror example, the spring tides at New Moon. If
the earth. is at her aphelion distance (rom the 8un, and
the moon in apogee, as we see represented at A, Fig. 6,
the attraction of both the sun and moon will be less thaD
their average amount, 80 that there will be but a moderate spring tide; but if the moon is in perig"!3e, and tbe
earth at' ber perihelion distance, as seen at D, both the
sun and ~oon, being at their nearest points to the earth,
and in conjunction, \vill exert their full attractive inftu.
ence upon the earth; and the spring tide will be unu.ually high, as shown on the map.
2. AtE the earth is near her perihelion, and tbe
mOOD in opposition and in apogee. In such a case the
or
I
..
] 28
OTDB. INBQUA.LITIES OF TBB TmBS•
• un has his gr«J,#,eBt· agency in produoing the tidel and
the moon her l«ut. This will tend to equa:lize their
fOrces, .and only an ordinary spring tide will be pro.
duced.
3. The IMigh,t of the tide-wave in different parts of the
. world is exceedingly' various, owing to its being crowded
into narrow channels in lOme in8tances, and to various
other local causes. In open seas the spring tides aTe
about eleven, and the Deap tides about seven feet. At
London the spring tides rise to the height of nineteen feet;
at the mouth of the Indus, thirty (eet; in the river Sev.
em, England, forty feet; at St. Maloes~ in France, fortyfive feet; and at Cumberland, Bay of Fundy, seventy-one
feet. This last is the highest tide in the world, and is
caused by the meeting of the great northern and southern
tide-waves of the Atlantio, which here come together in
opposite directions. .
The height of tides on dHFerent portiODS of the westem
continent has been given as follows:
Cumberland, Bay of Fundy,.
•
•
•
•
Boston,
New Haven,
•
•
•
New York,.
•
•
•
Charleston, s. C~,
•
•
•
•
•
•
•
• 71 feet.
• 11 "
•
8
• 0"
•
6"
eel '
This table seems to accord well with the theory JUst
named, in regard to the cau, of the excessively high
tides in the Bay of Fundy.
4. The lagging of the tide. . wave behind the moon
(93) is greatly mOdified by local causes. Though the
tides are usually highest about three hours after the
moon has passed the meridian, it is often retarded by
shoals and channels, an61 by Btriking against oapes and
headlands, so that, as exceptions to the general rule, high
tides bappen at all distances of the moon from the meridian.
5. Lakes and inland seas have no perceptible tides, in
consequence of their incoDsiderable magnitude, as com·
pared with the waters of the ocean.
6. Dr. Herschel Qbserves that the actiOIl of the Bua
APSIDBI OF TBB MOON'S OIlBIT.
129
in
and moon produoes tidu in ,he atmoBpAere, as well as
the water; and that delicate observations have rendered
them sensible and measurable. The pupil will find a
remark "concerning titU. OR the IUtI, in Chapter VII.,
where the various theories of the solar spots are oo~8id­
ered.
Lesson 00.
XOTION OP THE APSIDBS OF THE IIOON'S ORBIT.
(Map 14.)
At th.e close of Lesson 73, we promised in this chapter
to' speak of the motion or revolution of the moon's apaide,.
The ap.ide. of the moon's orbit are her perihelion and
aphelion points in her orbit; and the line of the apsidel
is a line drawn through those points, as shown in Fig. 6,
wherever the moon's orbit is represented. At A this lin~
is marked M A.
N ow the motion of the apaide8 is the revolution of these
points around the ecliptic from west to east. The map
shows this revolution as we trace the mOOD around from
in which pll.ce the line of the apsides, or the rna·
A
jor ;. xis of the ellipse, is at right angles with itself, as
aho· n at A.
The apsides of the moon's orbit make a complete revolution in about nine y~ars. In four and a half yean
the line A M will shift ends, 80 that the perihelion point
M will be towards the sun; and in four and a half years
more it will shift ends again, so that the moon will reach
her perigee again at M, or in the same part of the heav.
ens. In this wa.y the apsides constantly advance east.
ward, till, at the end of nine yeara, they finish a complete
revolution.
It will not be supposed, after what we have said above,
that the apsides shift ends IUddtmly, or all at once. This
is not the case. Their motion is gradual and uniform, as
Gown on the map.
As already stated in the ohapter on Eolipses, the mo.
tion of the moon's apsides must always be taken into the. .
1F,
•
130
DBSCBII'TION OF COK.TAKT BODIBS.
account in predicting their ocourrence,' as well u in the
explanation or the tides.
CHAPTER VI.
OF COMETS.
Lesson 97.
GENBRAL DESCRIPTION
or
COKETAltY BODIBS.
(Map 10.)
1. CollETS are the most singular class of bodies belong
ing to the Solar System. They derive their name frolla
the Greek word coma, which signifies bearded or kairy.
2. A comet usually consists of three ~arts-the Nuclew, the En'Oelope, and the Tail. . The Nucleu is what
may be called the body or lead of the comet, as seen at
N, on the map. The En'Delope is the nebulous or hairy
covering that surrounds the nuoleus. It may be:ren
around the nuclei of several of the specimens on the lap,
and especially that of 1585. The Tail of a comet· an
expansion or elongation of the envelope.
.
3. Some 90mets have no percephhle flUCltUl, their entire
structure being. like that of a thin vapory cloud, passinI'
rapidly through the· heavens.
4. Many comets have simply the envelope, 'fIJiiIumt
tailor elongation. Such were those that appeared in
1585 and 1763, the former of w~ich will be found on the
map.
5. Cassini describes the comet of 1682 as being f~
round and QJl bright QJl JU'Pit.er, untAout eve. an en"elupe.
But these are very rare exceptions to the general charaoter of cometary bodies.
6. The tails of comets usually lie in a direction 0f1P0me to tAe BUn; 80 that from perihelion to aphelion they
precetk their nuclei or heads j or in other worda, cometa
.ft,
DBSCRIPTION OF COMETA.RY BODIES.
131
.eem, after having passed their perihelion, to back out of
the Solar System. See Map 2 .
.7. The comet of 1823 is said to have had two taila, ODe
of which extended to1Dards the sun. This comet may be
eeen on the map, with a portion of its orbit. The sun is
supposed to be on the left, and the comet passing down
towards its perihelion., Its nucleus and envelope are distinctly represented.
, 8. The tails of comets are usually curved more or less,
being concave towards the region from whence they come.
This is well shown in the comets of 1811, 1823, and 1680.
That of'16~9 is said to have been curved like a Turkish
.bra, as shown on the map.
.
The C4IUe of tbis curvature of the tails of comets is
supposed to be a very rare ethereal substance, which per.
vades space, and offers a slight resistance to their progress.
or course it must be almost infinitely attenuated, as the
comets themselves are a mere vapor, which .'could make
no progress through the spaces of the heavens 'were they
not yery ,nearly a vaouum., They could-no more pass a
medium as dense as our atmosphere, than an ordinary
cloud could pass, through the wate~s of the sea.
.
9. ~mets ~av, been known to exhibit 8f.."eral tai14 at
tbe' same time. That of 1744, represented on the map,
had no less than ail: taila spread out in the heavens like
an enormOus fan.,
.'
.
10 .. The tails . .of comets 'do· not continue of the aame
Uniform length. They incretUe both in length and breadth
as they approach the SUD, and contract as they recede from
))im, until they 9ften nearly disappear before the comet,
gets out of sight.
'
11. Instances have ocourred in which' tails of comets
have been BUddenly 6lpanded or elo-ngau,d to, a great distance. This is said to have been the case with t,be 'great
comet of 1811.
.
12. or the p1&yaical nature of comets little is known.
That they are·.in general ve~y light and "apo/', bodies ia
evident (rom the fact that stars have sometimes been seen
even through their deri~e8t portions, and are generall)
visible through their tails; and from th~ little attractivo
I
132
MA.GNITUDES, BTC., OF COMETS.
influence they exert upon the planets in causing perturbs. tions. While Jupiter and Saturn often retard and delay
comets for months in their periodio rev 01 utions, comets
have not power in turn to ktuten the time of the planet.
for a single hour; showing conolusively that the relative
masses of the comets and planets are almost infinitely
disproportionate.
Such is the extreme lightness or tenuity or cometary
bodies, that in all probability the entire mass of the
largest of them, if condensed to a solid substance, would
not amount to more than a few hundred pounds. Sir
Isaac Newton was of opinion that if the tail of the largest
comet was compressed within the spaoe of a cubic inch,
it would not then be as dense as atmospheric air! The
comet of 1770 got entangled, by attraction, among the
moons of Jupiter, on its way to the sun, and remained
near them for four montha; yet it did not sensibly affect
] upiter or his mooDS. In this way the orbit8 of comelS
ar.e often entirely changed. That they are in themselves
upaque bodie" and aline only by reflectitm, is evident from
their sometimes exhibiting distinot pkaae,; from their in.
creased brightness as they approach the sun; and from
the known difference in the properties. of direot and re·
flected light. The idea that they are: in reality, "fiery
bodies," is unquestionably erroneous.
Lesson 9S.
IUGNITtrDBS, VBLOCITJBS, .A.ND TBftlPBRA.Tl11lB 01' COIIBTS.
(Map 10.)
1. The REA.DS or ftueld or comets are comparalifJel,
Mall. The following table shows the estimated diameter
in five different instances.
The comet ol1778, diameter of head 33 mil81.
"
1805,
"
36"
"
1799,
"
482"
"
1807,
.,
666"
..
1811,
"
428"
• •CHfITU'DBI, BTC., OF COQTS.
or
133
or
2. The TAILS
comets are often
enormoul length
and magnitude. That of 871 before Christ was 600 long,
covering one third of the visible heavens. In 1618, a
comet appeareo whioh was 1040 in length. Its tail had
Dot all risen when its head reached the middle of the
heavena. That of 1680 (see map) had a tail 700 long,
80 that though its head let soon after sundown, its tail
eontinued visible all night.
The following table will show the length of the tail.
9( some of the most remarkable oomets, both in degreea
ud in miles. They will be characterized only by the
year when th~y appeared.
B. c. 371,
A. D. 1456,
600
60
1618,
1680,
1689,
1744,
1'769,
1811,
1843,
104
"
"
"
"
"
"
"
70
68
30
90
23
60
·
•
-·
-
•
•
•
140,000,000 miles.
70,000,000 "
65,000,000 "
123,000,000 "
100,000,000 "
85,000,000 "
48,00(},000 ". .
182,000,000 "
130,000,000 "
As these Mtimates are the angles under which the cornela
were viewed fr(1fA tAe ellrti, the length of their tails in
miles would not be proportional to the angle merely, as
their diataf&Cu must. also be taken into the acoount. .~
the comet of ItJ43, 'with all angular length of only 600
was longer in fact by 65,000,000 miles than:~be comet
or 1618, with aD angular lellgth of 1040 • At the time
of measurement the latter was much nearer to the earth
than the former· when his dimetl8ions were estimated.
The pupil should look up the comets named in the
above table, 80 far as laid down on the map.
3. The VELOCITY with which comets often lDOye, i.
truly wonderful. Their motions are accelerated &8 they
approach, and retarded as they recede from the sun ;. 10
that their velocity is greatest while passing' their perihelions. The comet of 1472 described an arc or the
heavens of 1200 in extent in a single day! That or
. 12
--
134
PBRIODS, BTC., OP COJOTS.
or
1680 moved, when Dear its perihelion, at the rate
1,000,000 miles per hour.
4. The TEMPERA-TUBE of some comets, when nearest
the sun, must be very great. That of 1680 came within
180,000 miles of the Bun's surface, and muat have re.
ceived 28,000 times the light and heat which the earth
receives trom the sun-a heat more than 2,000 times
greater than that of red.hot iron! What ~ub8taDce can
a comet be composed of to endure the exfremes of heat
and cold to which it is subject 1 Some have supposed
that their tails were caused by the sun's light and heat
rarefying and driving back the vapory substance composing the envelope.
Lesson 99.
PBllIODS, DISTANCBS, AND NUMBER OF COMBTS.
(Map 15.)
1. The PERIODS of but few comets are known. That
of 1818, called" Encke'a Comet," has a period of only 3l
years. Biela'8 Comet has a period of 6t years. That 01
1682 (then first noticed with care, and identified as the
same that had appeared in 14:5(J, 1531, and 1607) has a
period of about 76 years. It is called Halley" Comet,
after Dr. Halley, who determined its periodic time.
The great comet of 1680 has a periodic time of 57()
years, 80 that its next return to our system will' be in the
year 2,250. Many are supposed to have periods of thou.
sands of years, and some have their orbits so modified by
the attraction of the planets as to pass off in parabolic
curves, (0 return to our system no more.
Prof. Nichol is of opinion that the greater Dumber visit
our system but once, and then tty off in nearly straight
lines till they pass the centre of ·attraction between the
Solar System and the Fixed Stars, and' go to revol va
around other .suns in the far distant heavens.· Sir John
Herschel expresses the same sentiment.
.
I
t
.- Solar System, p. 135.
t Treatise, American Rd. p.. 189•
•
JtBIlODS, BTO., O. OOUTS.
135
2. The DISTANCBS to which those comets that return
must go, to be 80 long absent, must be very great. Still
their bounds are set by the great law of attraction, . for
were they to pass the point "where gravitation turns the
other way," they would never return. But some, at
least, do return, after their" long travel of a thousand
years." What a sublime conception this affords us of
the almost infinite space between the Solar System and
the Fixed Stars!
The perihelion distances of the various comets that
have appeared, and whose elements have been estimated
by astronomers, are also exceedingly variable. While
lOme pa~ very near the sun, others are at an immense
distance from him, even at their periheli~n. Of 137 that
have been particularly noticed,
30 paased between the Sun and the orbit of Mercury j
44 between the orbits of Mercury and Venus;
34t ' "
"
"
Venus and the Earth;
23"
6
"
8. The
"
."
"
"
the Earth aDd Mars;
~ars and Jupiter.
of comets belonging to, or that visit,.
the Solar System is very great. Some have estimated
them at several millions. When we consider that most
comets are seen only through te~escope&-an instrument
of comparatively modern date-and that notwithstanding
this some 450 are mentioned in ancient annals and
chronicles, as having been seen with the naked eye, it is
probable that the above opinion is by no means extra vagallt. It is supposed tbat not less than 700 have been
seen at different times since the birth of Christ. The
paths of only about 140 have been determined.
The extreme difficulty of observing comets whose
· nearest point is beyond the orbit of Mars, is supposed to
account Cor the comparatively small number that have
·been seen without that limit; and the proximate uniform.
ity of the distribution of their orbits over the space in.
cluded within the orbit of Mars, seems to justify the conclusion, that though seldom detected beyond his path,
they are nevertheless equalJy distributed through all the
NUMBER
136
DJUCftOlI,
ne., OF OOIlBft.
of the IOlaJl heayeDl. ReaSODiBg upon this hypothesis, Prof. Arago conclude8 that there are- probably
. . . fIIilliDu o( comets that belong to or visit the Solar
8p8ce8
Sy8tem.-
Le880D
100.
DUlBCTIO!l, ORBITS, A.ND !lA-TUllB 0' COJIBTS.
(Map 15.)
1. The DlllBCTION ot- comets is 88 variable as their
torms or magnitudes. They enter the Solar System from
all points of the heavens. Some seem to come up from
the immeasurable depths below the ecliptic, and, having
doubled "heaven's mighty cape," again plunge downward with their fiery traiDs, and are lost for ages in the
eth~real void. Others appear to ~me down from the
zenith of the universe, and having doubled their perihelion, reascend rar above all human vision. Others again
are dashing through the Solar System, in all possible directions, apparently without any prescribed path, or any
guide to direct them in their eccentric wanderings. Instead of revol viog uniformly from east to west, like the
planets, their motions are direct, retrograde, and in every
conceivable direction.
~. It is remarked by a late writer,t that the average
ifaclinaticn&8 of all the planes in which the comets now on
record have been found to move, is about 90°. This he
regards as a wonderful instance of the goodness of Providence, in causing their motions to be performed in a manDer least likely to come in contact with the earth and the
other planets.
8. The (orm or the comets' orbits is generally that o(
an ellipse greatly flattened or'elongated. The sun being
near one end of the ellipse, and the planets comparatively
in his immediate neighborhood, the comets are in the
vicinity of the sun and planets but for a. short time, and
• Arago and Lardner', Astronomy, p. 70.
t Prot Keadall of Philadelphia.
•
-~--T""""-
DI1lBCTION, BTC.,
!
•
_.
or COMBTI.
137
then hasten outward again, beyond the limits of human
vision, even with the aid of the best .-telescopes, to be gone
even for centuries!
4. Comets were fonnerly regarded as harbin~ers
famine, pestilence, war, aod other dire calamiues. ID
one or two instances they have exoited seriou8 appre.
hension that the day of judgment was at hand; and that
they were the appointed meesengers of Divine wrath,
basting apace to bum up the world. It may be well,
therefore, to devote a paragraph to the question, Are
t;omeu dangerow in the Solar SyBtem 1 That they are
not, will be evident when we consider,
First, that there is scarcely the remotest probability
of a collUian between the earth aod a comet. It has
been determined, upon mathematical principles, and after
the most extended and laborious calculation, that of
281,000,000 of chances there is only one unfavorable,
or that can prod uce a collision between the two bodiefJ.
The risk, therefore, to which the earth is exposed of being
.t~uc" by a oomet, is lik~ the chance one would have in
a lottery, where there were ~~,O()O,OOO black balls and
but one white one; and where the white ball 'must be
produoed at the first drawing to secure a prize.
In the second place, if a oomet were to come in direct
collision with the earth, it is not probable that it would be
able even to penetrate our atmosphere; much less to duh
the world in pieces. Prof. Olmsted remarks, that in suoh
an event not a particle of the oomet would reach the
earth-that the portions encountered by her would be
arrested by the atQlosphere, and probably ioftamed; and
that they would perhaps exhibit on a more magnificent
scale than was ever before observed, tbe phenomena
shooting sters, or meteoric showers.· The idea, tber~
{ore, that comets are dangerous :visitants to our system
more support from superstition than from reason or
1C1ence.
I cannot better conol ude this chapter than in the
language of the lamented Burritt: "What regioD. theae
or
or
ha:s
•
138
••• A.O UIPBOTIKG 'I'D lVII, BTC.
bodi. visit, when they pus beyond the limits or our
Yiew; upon what errand. they ~me, when they again
revisit the central parts or our system; what is the
difference between their ·physical constitution and that
or the .un and planeta; and what important ends they
are destined to accomplish in the economy or the uni.
Yerae, are inquirie. which naturally arise in the mind,
but which lurpa.- the limited powers of the human ua
clentaading at present to determine."
CHAPTER VII.
OF THE SUN.
Le8H. 101.
a.naA.L :aBMA.:aXS RBSPBCTIlfG
TBB BUX-ITS JUaNI•
.
NDB, BTO.
(Map 4.)
ALTHOUGH it has been found neceasary to give mal1Y in.
terestios facts respeoting the 8un, in the precediDg lea..
tona, it is thought important to repeat them· here, with
others, in a more Bystematic order; and with opportunity
tor deeoriptioD8 and explanations more in detail.
Of all the celestial objects with which we are acquainted, nODe make 80 strong and universal an impression upon
our globe as does the Su. He is the great oentre of the
Solar 8yste~ vast and fiery orb, kindled by the AI.
mighty on the mom or oreatioD, to oheer the dark aby88,
and to pour his radiance upon 8urrounding worlds. Com.
pared with him, all the 101ar bodies are of inconsiderable
dimensioD8 j and without him, they are wrapped in the
pall of intenninable night.
.
The aun is 886,000 mileS in diameter. Wen a tunnel
opened through hi. centre, BDd a railway laid down, it
would require,· at the rate of thirty mil. per hour, nearl.,
-----.
...---.--~
.....-~.----......-- -
--ROTS OlC TIIB BUK-Tlmla XV.DIl.
]
39
three and a haIr years (or a train of cars to paas through
it. To traverse the whole circumference of the SUD, at the
same speed,. would require nearly elev~D years. His
diameter is 112 times that· of the earth, and his rna.
1,4:00,000 times as great. He is 500 times lar~er thaD
all the rest of the Solar System put togeth~ The mean
diameter of the moon's orbit is 480,000 mlles; and yet
were the sun to take the place of the earth, be would fill
the entire orbit of the mOOD, and extend more than 200,000
miles beyond it.on every side.
The. form of the SUD is that of a 8pAeroid; his equatorial tieing somewhat greate.r thaD his polar diameter.
The map referred to exhibits the relative diameters of the
lun and planets.
I
•
Lesson
IO~.
SPOTS ON THE SUN-JfHBIK NUXBB••
(Map 4.)'
By the aid of telescopes a variety
qol6 are often
discovered upon the sun's disc. Their . . .6er is exoeedingly variable at different times. From )611 to 1629, a
period of 18 years, the sun was Dever found olear of
spots, exc~pt for a few days in December, 1624. At other
times twenty or thh1Y were frequently seen at once; aa.d
at one period, in 1825, upwards of fifty were to be seen.
Prof. Olmsted states that over one huodred are sometimes
visible. From 1650 to 1670, a period of 20 yeare,
ecarcely any spots were visible; aod for eight years,
from 1676 to 168', no spOts whatever were to be seen.
For the last 46 years, a greater or less Dumber of 8pots
have . n visible every year. For several days, during
the latter part of September, 1846~ we could count six ..
teen of these spots which were distinctly visible, aDd moat
.of them well defined; but OD the 7th of .October follow ..
ing, only six small .pots were visible, though the orne
telescope was used, and oirou~tanoes were equally
yorable.
.
or
r..
"~
I
!
· LeSSOR
103.
KA.T11:aB OF THE SOLA:a SPOTS.
(Map
C'"
4.) .
or
The appearance of the solar spots is that
a dark .11lurrounded by a border le88 deeply shaded, called
a peRllfMTa. They are both well represented on the
map.
When seen through · a telescope, the sun presents the
appearance of a Tut globe, wrapped in an ocean of flame,
with the spots, like iucombustible islands, floating in the
fiery aby88~ The principal facts by which we are to
judge of their nature and eGU8U, are the following:
1. The Bun is often entirely de8tUKte of spots.
2. When they are to be seen, the same spots do Dot
regularly reappear on the east; and pass around, with
every successive revolution, to the west.
3. They are exceedingly variable as to .umber and
flUJ6"itude •
,. They have been known to b,.eak it116 piecu, and die
vide, and even finally to di,appear altogether in a very
Ilion time.
1\. They sometimes break out again in the same places ;
and Dew onel often break out where none were per.
ceptible before.
6. When they disappear, the central dark lpot alwaYI
contracts into a point, and vanishes before tbe penumbra
or border disappears.
7. In the neighborhOod of the large spots, tbe surface
the IUD is covered with strongly-marked streak. or
arms, more luminous than the rest, called facuI., among
which the spots often break out. The (lark spots are
IOmetimes called flUlCUke.
8. The spots are all found within 800 or the 8un's
equator, or in a zone of 600 in width.
.
9. In a aeries of experimentl conducted by Prof.
HeDry, of Princeton, by means .of a thermo-electrical
or
j
I
I
I
..
......... -
---_.-
141
WAT1JD 0. 'I'D SOLAIl aI-OTl.
apparatus, applied to an image of the 8UIl throwD on a
screen from a dark l'OOID, it was found that the spots
were perceptibly oolder than the surrounding light sur.
face.
Concerning theae wonderful spoll a variety of opinions
have prevailed and mahy curious theories have been
constructed. Lalande, as cited by Herschel, auggUt8
that they are the tops of mountains OD the 8un's surface.
laid bare by fluctuation8 in his luminous atmosphere;
and that thepenumbr. are the shoaling declivities
the mountains, where the luminous ftuid is lees deep.
Another gentleman,
some astronomioal knowledge,
supposes that the tops of the solar mountains are exposed
by tidu in the lun'. atmosphere, produced by plaaetary
attraction.
To the theory of Lalande, Dr. Herachel objects that
it is oontradicted by the sharp termination of both the in.
temal and external edges of the penumbre; and ad.
yances 88 a more probable tbeory, that " they are the
dark, or at least comparatively dark, solid body of the
sun i~lr, laid bare to our view by those immense fluotuations in the luminous regions of the atmosphere, to which
it appeara to be subjeot." Prof. Olmsted Buppana thi.
theory by demoDstrating that the spots must be "nearly
or quite in contact with the body of the sun."
In 1778, Prof. Wilson, of the University of Glasgow,
ascertaiDed by a aeries
observations that the spots
were probably "",an "C4Mtioa. in the luminous' matter
the sun;" the nuclei being their bottom, and the
umbne their shelving sides.· This conclusion varies but
little from that of Dr. Henohel, .ubsequently arri yed
or
or
or
or
at·t
.
.
• A .aJaable peper apon the aabject 01 the lOlar IpOIII, writteD ..,
the lameated Ebenezer Poner Muon, may be loud ia Iaia euelJMemoir, by Prot OIJDlted, pap 238.
t Nichol', Solar Sy.tem, pp. 121-116.
-
142
-~-
--".
MA.S.ITV». OF TJIIr SOU. SPOTS.
LessoD 104.
KA.GNITt1DB OF THE SOLAR SPOT&
(Map
4.)
The f1UJ8ftitude of the solar spots is as variable as their
Dumber. Upon this point tbe map will give a correct
idea; .a8 it is a pretty accurate representation of the
sun's disc as seen by the writer on the 22d ot" September,
1846. In 1199, Dr. Herschel observed a spot nearly
80,000 miles in breadth; and he further states, that
.others have been observed 'whose diameter was upwards
of 45,000 miles. Dr. Dick observes that he has several
times seen spots which were not less that
of the sun' 8
diameter, or 22,192 miles across.
It is stated, upon good authority, that solar spots have
been seen· by the naked eye-a fact, from which Dr.
Dick concludes that such spots could not be less thaD
50,000 miles in diameter.
The observations of the
writer, as above referred to, and represented on the map,
would go to confirm this deduction, and to assign a still
greater magnitude to some of these curious and interest.ing phenomeDa.
,
n
Le880l 103.
eVOLUTION OF THB SUX UPON HIS A.%I8.
(Map 4.)
The axis of the sun is inclined to tbe ecliptic 71°, or
more accur~tely 7 0 20'. This is but a slight deviation
from what we may call a perpendioular, 80 that in relation to the earth, he may be oonsidered as standing up
ao.d revolviDg with one of his poles resting upon a point
just half his diameter below the eoHptic. The proof
his revolution is the same as that by which we determine
the revolution of the planets, namely, the passage of spots
over his disc. He revolves in the same direction in
whioh the planets revolve around him, and the time 00..
or
--
-
-
.
•,
143
DIRBCTION', BTC., OF IOLA.:a SPOTS.
cupied in making a complete sidereal revolution is 25
days 10 hours. But when a particular spot has arrived
opposite any partioular atar from which it started, in tbe
direction of which the ~arth was 25 days and 10 hourS
.before, the earth is found to have advanced some 240, or
1,700,000 miles in her orbit; and the sun must actually
tum a little more than ooce round, to appear to make a
complete revolution to a lteholder on the earth. His q.nodic revolution consequently requires 27 days 71 hours,
or Dear 46 hours more time tha.n his sidereal revolution.
Lesson 108.
DIaBeTION, MOTIONS, A.ND PRASBS OF '1RB SOLA.R SPOTS.
'Map 4.) ,
As .the result of the sun's motion uptn his axis, his
spots always appear first on his eastern limb, and pass off
or disappear.on the west. But though the direction of
the spots, as viewed from the earth, is from east to west,
it only proves his Dlotion to coineide with that· of the
earth, which we call from west to east; as when two
spheres revolve in the 8ame direction, the sides towards
each other will- appear to move in oppome directions.
During one half of the passage of the spots across the
8un's disc, their apparent motion is accelerated; and during thA remainder it is relaraed.
This apparent irregularity in the motion of the spots
upon the sun's surface, is the necessary re~ult of an
equable 1J)0tion upon the surface
a. globe or sphere.
W hen near the eastern limb, the spots are coming partly
toward.. us, and their angular motion is but slight; hut
when near the centre, their angular and real motioDs are
equal. So, also, as the spots pass on ·to the west, it is
their angular motion only that is diminished, while the
Illotion of the sun upon his axis is perfectly uniform.
The figure of the sun affects Dot only the app~rent
,,~/ocity of the spots, but also their fortU.
W hen first
seeD on the east they appear narrow and' slender, al
.represented OD the left of Fig. 1. As they advance
or
•
144
PHYSICAL CORI"tH'U110K OF 'I'D
au••
westward, they cootinue to wideo tOr eDlarge till they
reach the centre, where they appear largeSt, wheD they
again begin to contraot, and are constantly diminished
till thef disappear.
Another result of the revolutioa of. the aOD upon all
axis inclined to the ecliptic, and the revolution of the
earth around him, is, that when viewed from our moveable observatory, tbe earth, at different .Uona of tbe
year, the direction of the spots seems materially to vary.
This fact is illuttrated by Fig. 2. In Jiloe we have, 80
to speak, a side view of the sun, his pole being inclined
to the lift.
course, then,
he revolves, his spots will
appear to 88Cend in a straight line. In September we
have passed around in our orbit, to a poiat opposite the
lOuth pole of the SUD, and the .pots 88em to curve upward. In December we have 8DOther side view of the
IUD, but we are opposite the point from which we had our
first view, and on, the other side of the ecliptio. The reBUlt is, that tbe poles of the SUD are now inclined to the
ri8ht; and' the spots, in passing over his diao, incline
downward. In March,. we reaoh a point opposite the
80ut" pole of the 8un, and the .pot.s in revolving aeem to
ourve downward.. The polar iDclination of tbe 8un, U
given in the figure, is greater than it actually is in nature,
(see Lesson 49 and Map 8 ;) the present design beiDl
merely to illustrate the principle upon which 'we account
Cor the peculiar motion Qf the solar spots.
or
as
Lesson 107.
PHYSICA.L CONSTITUTION OF TUB St1K.
Concerning the physioal aature of the SUD, yery little
,is known. As before said, it appears, wheD 8een through
a ~ele800pe; like a globe of fire, in a state of violent com.
motion or ebullition. La Place belieyed it to be in a
_ate of actual combustion, the spots' being immense cay.
ems or craters, cau~d by eruptioDs or exploeioDs
elastio ftuids in the interior.
'
The most probable opinion 18, that the body. &he BUD
or
or
1
~
-,,------......
-_.... "--- ...
-
--
-"
--.-
".--
..
-
.
-----
---- ._-
PRYSICA.L CONSTITUTION OP TBB SUN.
.
145
is opaque, like one of the planets; that it is surrounded
hy an atmosphere oC considerable depth; and that the
light is sent off from a luminous straJum of clouds, float.
ing above or outside the atmosphere. This theory accords
best with his density, and with the phenomena of the s0lar spots.
\
Of the temperature of the sun's surface, Dr. Herschel
thinks that it must exceed that produced in furnaces, or
eVt-n by chemical or galvanic processes. By the law relative to tbe diffusion of light (Lesson 12) he shows that
a body at the sun's surface must receive 300,000 times
the light and heat of our globe; arid adds that a far less
quantity of 801ar light is sufficient, when collected in the
Cocus of a buming-glass, to dissipate gold and platina into
vapor·
.
The same writer observes that the most vivid flames
disappear, and the most intensely ignited solids appear
only as black spots on the~disc of the sun, when held between him aDd the eye. From this circumstance he in.
fen that however dark the body o( the sun may appear,
when seeD through its spots, it may, nevertheless, be in a
state of most intense ignition. It does not, however, follow
of necessity that it must be so. The contrary is at least
physically possible. A perfectly rtjlecti1Je canopy would
effectually defend it from the radiation of the lurninous re.
gioos above its at~phere, and no heat would be conducted
downward through a gaseous medium increasing rapidly
in density.
The great mystery, however, is to conceive how 80
enormous a conftagratioD (if· such it be) can be kept up
(rom age to age. Every discovery in chemical science
here leaves us completely at a loss, or rather seems to
remove farther from us the prospect of explanation. If
conjecture might be hazarded, we should look rather to
the knowD possibility of an indefinite generation of beat
by friction, or to its excitement by the electric discharge,
than to any actual combustion of ponderable fluid, whether
IOlid or gaseous, for the origin of the solar radiation. *
I
• HellCbel'. Treatile on Astronomy.
13
146
TBB ZODIACA.L LIGII'l.
Les•• lOS.
,
THE ZODUCAL LIGHT.
The ZodUJcal Liglat is a faint nebulous light, resembling the tail of a comet, or the milky-way, which seems
to be reflected from the regions about the lun; and is
distinguishable from ordinary twilight. Its form is that
or a pyramid or cone, with its base towards the SUD, and
inclined slightly to the ecliptic. It seems to surround
the 8un on all sides, though at various depths, as it may
be seen in the morning preceding the 8UD, as well as in
the evening following him; and the bases of the cones
where they meet at the 8UD, are much larger than his
diameter.
The form of this substance surrounding the IUD, and
which is sufficiently dense to reflect his light to the
earth, seems to be that of a leu; or rather that of a
huge wheel, thickest at the centre, and thinned down
to an edge at the outer extremities. Its being seen
edgewise, Bnd ·only one.half at a time, gives it the appearance of two pyramids with th6ir bases joined at the
IUD.
Of the fUJture of this singular phenomenon very little
is positively known. It was formerly thought to be tbe
atmosphere of the IUD. Prof. Nichol says :-Of' this at
least we are certain-the Zodiacal Light is a phenomenon precisely similar in kind to the nebulous atmospheres of the distant stars, &0. Sir John Herschel re..
mark~, that it is manifestly of the nature of a thin
lenticl.. ''1.rly.formed atmosphe~e, surrounding the SUD,
and ex ..e. -ling at least beyond the orbit of Mercury, and
even of \ ·nus. He gives the apparent Ilngular distance of its vertex from the SUD, at from 400 to 90 0 ;
and the breadth of its base from 8 0 to 300 • It sometimes
. extends 500 westward, and 700 ea8t of the aun at the
same time.
. .
In regard to its atmospheric character, Dr. Diok observes, that this opinion now appears extremely dubious;
and Prot Olmsted refers to La Place, as ahowing thai
•
•
...
I
KOTION OP THB SU'N IN SPA"B.
. 147
the BOlar annosphere could never reach 80 far troOI th.
SUD 88 this light is seen to extend.
Another class of utronomel'8 suppose this light, or
rather the substance reflecting this light, to be some of
the original matter or which the sun and planets were
composed-a thin nebulous substance in a atate of con.
densation, and destined either to be consolidated into oer
planetary worlds, during .the lapse oC coming agel, or to
settle down upon the sun himself as a part of his legitimate substance. This theory will be noticed again when
we come to speak of Nebulae and Nebulous Stars, in the
~cond part of this work.
Prof. Olmsted supposes the Zodiacal Light to be a
nebulou8 body, or a thin vapory mass revolving around
the sun; and that the Meteoric SlunDera, which have occurred (or several years, in the month of November, IDay
be derived from this body. This is the opinion of Arago,
Biot, and others.
The best time for observing the Zodiacal Light is on
clear evenings, in the months of March and April. It
may be seen, however, in October, November, and December, before sunrise; and also in the evening sky.
-It is an interesting fact, stated by Prof. Nichol, that
this light, or Debulous body, lies in the plane of the sun'.
equator. A line drawn through its transverse diameter,
or from one apex of the pyramids to the other, would
cross the axis of the sun at right angles. This fact
would seem to indicate a revol ution of this curious 8U bstance with the sun upon hi, axis.
But, 88 already stated, the subject of the Zodiacal
Light is in an unsettled state. After considering the
various {acta and theories stated, the learner Rlust wait
till future observations and discoveries shall furnish some.
thing upon this point more definite and satisfaotory.
Lesson 109.
MOTION OP TO S111'( IN SPA.CK.
Although in general terms we speak of the aUD as the
ed centre of the Solar System, still the sublime and
148
KOTIOlf OF TD St1K IN SPA.CB.
astonishing fact has been ascertained, that the sun, and
the whole Solar System, h,afJe aft actual motioR in apace.
Indeed the sun may be said to have three distinct motiona.
1. It has a revolution upoo its own axis;once in 25
days.9i hours, as described in Lesson 105.
2. "I t has a periodical motion, in nearly a circular
.direction, around the cOin moo centre of all the planetary
motions; never deviating from its position by more thaD
twice its diameter." From the known laws of gravitation, it is certain that the sun is affected in 8Qme measure
by the attraction of the planets, especially when many of
them are found on the same side of the ecliptic at the
Rrne time; but this would by no means account for 80
great a periodical motioD.
3. It is found to be moving, with all ita retinue
worlds, in a vast orbit, around some distant and unknoWll
centre. This opinion was first advanced, we think, by Sir
William Herschel; .,but the honor of actually determining
this interesting fact belongs to Struve, who ascertained
Dot only the direction of the sun and Solar System, but
also their velocity. The point of tendency is towards the
constellation of stars called Hercules, Right Ascension
269°, Declination 35°. See Lessons 47,48. The velocityof the SUD, &c., in space, is estimated at about 28,OOU
miles per hour, or nearly 8 miles per second!
With this wonderful fact in view, we may no longer
consider the su n as fixed and stationary, but rather 8S a
vast and luminous planet, sustaining the same relation to
some central orb, that the primary planets 8ustain to him,
or that the secondaries sustain to their primaries. Nor
is it necessary that the stupendous mechanism of nature
should be restricted even to these sublime proportions.
The sun's central body may also have its orbit, and its
centre of attraction and motion, and 80 on, till, as Dr.
Dick observes, we come to the great centre of all-to the
or
THRONE OF GOD.
Since the above was written an article has appeared in
several European journals, announcing the probable discovery of the sun'8 central orb; the inclination of Ail
twbit to the plane oj the ecliptic; and his periodic time!
KOTION OF THB SUN
, IN SPlCB.
149
As it contains several interesting -calculations, and is
otherwise a remaFkable paper, it is here copied for the
benefit of the student.
THB CBNTRAL SUK.
At the close of the meeting of the Royal Irish Acad.
emy, on the 14th of December, [1846,] Sir William
Hamilton announced that he had just received from ProCessor Midler, of Dorpat, the extraordinary and exciting intelligence of the presumed discovery of a central
sun!
By an extensive and laborious comparison of the
quantities and directions of the proper motions of the
stars in various parts of t~e heavens, coQ1bined with indications afforded by the parallaxes hitherto determined,
and with the theory of universal gravitation, Professo·r
Madler has arrived at the concl uaion that the Pleiades
form the central group of our whole astral or sidereal
system, including the Milky Way and all the brighter
"tars, but exclusive of the more distant nebulm, and of
the stars of which those nebulm may be composed. And
within this central group itself he Pias been led to fix on
the star Alcyone, (otherwise known by the name of
• Tauri,) as occupying exactly or nearly the position of
the centre of gravity, and as entitled to be called the
• .
central sun.
Assuming Bessel's parallax of the star 61 Cygni, 1.ong
since remarkable for its large proper motion, to be cor.
recti y determined, Miidler proceeds to form a first approximate estimate of the distance of this central body
from the planetary or solar system; and arrives at the
(provisional) conclusion, that Alcyone is about thirtyfour million times as far removed from us, or from our
own sun, as the latter Iuminary is from us. I t would,
therefore, according to this estimation, be at If'ast a million
times as distant as the new planet, of which the theorp.ticalor deductive discovery has been so greht and beautiful
a triumph of modern astr9nomy, and so striking a confir.
mation of the law of Newton. The saRle approximate
determination of distance conducts to the result, that the
13·
•
150
NBBlJUll TBBORY.
,
light oC the central slln occupies more than fi,'e centurie.
in travelling thence to U8.
The enormous orbit which our own sun, with the earth
aud the other planets, is thus inferred to be describin~
about that distant centre-not indeed under its influence
alone, but by the combined attractions of all the stars
which are nearer to it than we are, and which are estimated to amount to more than one hundred and seventeen
millions of masses, each equal to the totaJ mass or our
own Solar System-is supposed to require upwards
eighteen millioru of ,ear. for its complete description, at
the rate of about eight geographical miles in every second
of time.
The plane oC this vast orbit oC the sun is judged to ha va
an inclination I()f about eighty.four degrees to the ecliptic,
or to the place of the annual orbit oC the earth; and the
longitude of the' ascending node of the former orbit on the
latter is concluded to be nearly two hundred and thirtyleven degrees.
or
CHAPTER VIII.
MISCELLANEOUS REMARKS UPON THE SOLAR SYSTEM.
.
•
Lesson 110•
IfBBULAll TBBOllY 01' THE ORIGIN OF THE SOLAR SYSTKII.
IT was the opinion oC La Place, a celebrated French
•
astronomer, that the entire matter of the Solar System,
which is now mostly found in a consolidated state, in the
lun and planets, was once a vast nebu1o., or gasepus vapor, extending beyond the orbits of the most distant
planets-that in the process of gradual condensation, by
attraction, a rotary motion was engendered and imparted
to the whole mass-that this motion caused the consolida.
ting matter to assume the (orm of variouS' COD cent rio
rings, like those of Saturn; and, tinally, that these ringa,
collapsing, at their respective distances, and still retaining
~-- ~-----------
---.--
--~--
-...- --
--
-- -------
- --
--
--------- ---
NBBUL.&.B. THBOB.Y.
151
their motion, were gathered up into planetl, as they are
now found to exist. This opinion is supposed to be favored, not only by the fact of Saturn's revolving ring&,
but by the existence of the Zodiaoal Light, Qr a resisting
nledium about the sun, (108,) and also by the character
of irresol yable or planetary nebullll, hereafter to be de.
scribed.
.
'
On the other hand, the nebular theory is open to many
plausi ble, if Dot insurmountable objeotions.
1. It seems to be directly at varianoe with the Mosaio
account of the creation of the 8un, moon, and star8.
The idea that the sun and all the planets were made up,
110 to speak, out .of the same general mass, not only
throws the creation of this matter back indefinitely into
etprnity, but it substitutes the general law of attractiOD
for the more direct agency of the Almighty. The crea.
tion spoken of in the Bible thus becomes, not the origi'114ti716 of things that did not previous]y exist, but the mere
organization, or 4"angement of matter already existing.
And as attraction-the supposed agency in this arrange.
ment-is still in operation, the creation of all things i.
resolved into an ordinary, we might almost say, an every.
day occurrence.
2. The supposed c,onsolidation of the nebulous mass,
in obedience to the general law of attraction, does Dot
itself account for the -rotary motion which is an essential
part of the. theory • Under the influence of mere attrae.
tion, the particles must tend directly towards the centre
of the mass, and consequeI\lly could have no tendency to
produce a rotary motion during the process of condensation.
S. The variation of the planetary orbits from the
plane of the 8un's equator, contradicts the Nebulat
theory. If the several primary. planets were successively. thrown off from the general mass, of which the
sun is a part, they could not have been separated from
the pa.rent body, till they were near the' plane of its
eq nator . Now, as the Bun is assumed to l)6 a part or
the same mass, revolving still, the theory would require
that the portions now separated from him and called
or
,
,
152
LAwa OP PLANBTAllY KOTIOK.
planets, should still revolve in the plane of his equator.
But instead of this being a (act, it is found that some of
them vary from this plane to the amount or near 420.
See Lessons 32 and 105, and the maps.
4. Ffhis theory assu mes not only that the primary
planets were thrown off from the parent mass by its
rapid revolution, but that the primaries in tum threw off
their secondary plane\S or satellites. These of course,
then, should all revolve in the plane of the planetary
equators respectively, and in the direction in which th~ir
primaries revolve. But their orbits not only depart from
the plane of the eqllators of their primaries, Jupiter's
sateUites excepted, (Lessons 70, 81, 82, 83,) but the
moons of Herschel actually have a retrograde or back.
card revolution. See 83.
5. If the sun and planets are composed
what was
originally the same mass, it will be necessary to show
why they differ so materially in their physical nature-why the sun is self-luminous and the planets opaque, &c.
But we have not room to discuss the subject at length
in this treatise. It is but justice, however, to say, that
men eminent for learning and piety have advocated what
is called the Nebular TAeory, in the belief that it was per(ectly consistent with the Mosaic account of the creation
or the heavens and the earth. If the opinion or the wri.
ter is desired, he is frank to state, that while he acknow.
ledges the force of some of th~ considerations urged in
its IU pport, he has not yet seen reason for adopting this
&hory of the formation of the Solar System.
or
Lesson III.
LAWS
O~
PLANBTARY MOTION.
(Map 7.)
The~e ~re
three general principles which govern
the lnotlons of all the planets. These were first discov.
~red t,y Kepkr, a German astronomer, from wbom th~y
~-
...
--
i
LAWI OF PLANETARY aOTION.
15'3
ha ve since been called Kepler' 8 lafIJ8. They are as fol.
lows:
_1. The orbit. of the Earth, and aU the PiaU", are
ELLIPSES,
having the Sun in the common IDea •.
"The ellipse is a curve, of an oval or elongated form,
all the points of which lie in the same plane. The
largest diameter of an ellipse is called the major,' or
tra1l8Verae tuU. It divides the curve into ,two equal
parts. The foci are two points in the transvene ax~
equally distant from the centre. If from any point or \
the curve two lines be drawn to the two foci, their 8um
will be equal to the transverse axis. Since ~e sun is
in one of the foci of the elliptical orbit of a planet, the
latter will, at different times, be at unequal distancel
from the sun." At whatever point in its orbit a planet
may be, a line drawn from its centre, to the centre or
the sun, is called the radiw "ector.
2. The radiua "ector, (or line dra1Dfl from t1&e centre of
the Sun to the centre of aftY Planet re'OoZ"iftg around it, l
describea equal areaa
i~
equal time,.
The nearer a planet is to the sun, the more rapid itt
motion, (19.) It follows, therefore, that if the orbit at
a planet is an ellipse, with the sun in one of the foci, its
rate of motion will be unequal in different parts of its
orbit,-swiftest at perihelion, and slowest at aphelion.
From perihelion to aphelion, the centripet~l more direct. .
Iy counteracts the centrifugal force, (20,) and the pla.net
is retarded. On the other hand, from the aphelion to
the perihelion point, the centripetal and centrifugal
forces are united, or act in a. similar direction. They
consequently basten the planet onward, and its rate 01
motion is constantly accelerated.
Now suppose when the planet is at a certain point
near its perihelion, we draw a line from its centre to the
centre of the sun. This line is the radi'IU "ector. At
the end or one day, for instance, after the planet bas
advanced considerably in its orbit, we draw another line'
in the same manner to the sun's centre, and estimate the
area between tbe two lines. At another time when the
planet is near its aphelion, we Dote the space over which
-------~
..
154
LAWS 01' PLAl'fBTAB.Y J[OTION.
the radius vector travels in one day, and estimate its
area. On comparison it will be found, that notwith.
standing the unequal "elocitg of the planet, and con.
sequently of the radius vector, at the two ends of the
ellipse, the area ove~ which the radius vector has
trft velled is the same in both cases. The same principle
whatever
obtains in every paJ1..of the planetary or
may be their elliptioity or the mean
oC the
planet from the sun; henCe the rule, that tAe JlJa~u
ducrilJe. equal area ;11 equal time,. *
8. TM .quare. of the penodic limu are
~
IAe mea1l tlUtatU;u from tAe
SUfi.
ce Take, Cor example, the earth and
periods are 865.2564 and 686.9796 days,
distances Crom the sun are in the pPln>.,."."j~.
1.02369; and it will be found that
(365.2564)2 : (686.9796)2 : : (1)1 :
(1.528~[IJ
"The m8.81 of the earth being Car smaller tha
the sun, the mOOD de~cribes a proportionally smal
round it in a -moment of time.
"So, Herschel, Saturn, and Jupiter having greate
than the earth, their satellites make greater
their primaries, in a moment of time, than our
round the earth. Still, this third law of Ke
in each secondary system. Among the sate
same system, the squares of the periodical ti
ways as the cubes of their mean distances
mary of the system."
According to these laws, which are known to prevail
throughout the ~lar System, many of the Cacts of astron.
omyare deduced from other facts 'previously ascertained.
Th~y are, therefore, of great importance; and should be
studied till they are, at least, thoroughly understood, if
not committed to memory. The first is illustrated in
several or the maps, and, as before said, the ingenious
teacher will readily illustrate the second by a simple
diagram upon a slate or black.board. It would be a very
useful exercise for the pupil to test the table in which the
~----------
IlEPB,£SBN'TA.TION OF THB SOld-a SYSTBM.
_
l. 56
dUtIl"ce. and periodic time, are given, by this third law-.
See Lessons 8 and lB.
Lesson II".·
MINIATURE REPRESENTA.TION OF· THE SOLA.R SYSTEM.
At the clo~ of his remarks·on the Primary Planets,·
Sir John Herschel has a most graphic and interesting
d~cription of the Solar System in miniature, which is
bere inserted for the perusal of the learner.
Choose any' well-levelled field or bowling-green. Oft
it place a globe two Ceet in diameter: this will represent
the SUD; Mercury will be represented by a grain of
mustard-seed, on the circumference of a circle 164 feet
in diameter for its orbit; Venus a pea, on a circle 284
f~.t in-diameter; the Earth also a pea, on a circle of
480 feet; Mars a rather large pin's head, on a circle of
feet; Vesta, Juno, Ceres., and Pallas, [also Astnea,]
-"grains of sand, in orbits of 1000 to 1200 feet; Jupiter a
moderate-sized orange, on a circle nearly half a mile
acrose; Saturn a small orange, on a circle of fouI-fiftbs
of a mile; and Herschel a full-sized cberry, or small
plum; upon a circumference of a circle more than a mile
and a half in diameter. • • • • •
To imitate the mot:ioM of the planets, in the above.
mentioned orbits, MercurY must revolve in its orbit in 41
seconds ; Venus in 4 mht. 14 sec.; the Earth in 7 min. ;
Mars in 4 min. 48 sec.; Jupiter in 2 h. 56 min.; Saturn
in 3 h. 13 min.; and Herschel in 2 h. 16 min.
So far as relative magnitude is concerned, it will be
easy to discover the general accuracy of Maps 2 and ~,
according to the representations of Dr. Herschel, all above
quoted. It is proper, however, to remark, that the maps
were d rawn by -the author by a regular and exact scale,
without any reference to the foregoing, or any recolleoits existence.
tion
8:?J.
or
.
\
-
• Treame, p. i7L
•
-
156
ORIGIN OlP THE ASTEROIDS.
Lesson 113.
WERE THB .lSTEROIDS ORIGINALLY ONE PLANET'
I. Some very curious speculations have been enter..
taiDed by astronomers in regard to the origin of the Asteroids. As in the case of the recent! y discovered planet
Le Verrier, the existence of a large planet between the
orbits of Mars and Jupiter was 8uapected before the Asteroids were known. This suspicion arose mainly from
the seeming chasm that the absence of such a body would
leave in the otherwise well. balanced Solar System.
2. The prediction that such a body would be disc<wered
in the future stimulated the search of astronomers, till at
length, instead or one large planet, five amall emu' were
one after another discovered. For the time of their dis.
covery, see Lesson 67.
.
8. From' certain peculiarities of the Asteroids, it haa
beeQ considered highly probable that they were originally
one large planet, which had been burst asunder by some
great convulsion or collision, and of which they are the
fragments. The grounds of this opinion are as follows:
(1.) The Asteroids are much.maller than any of the
other primary planets. · Lesson 14.
(2.) They are all at nearly the same tlirituace from the
BUn, as will be seen by Lesson 8.
(3.) Their periodio revolutions are accomplished in
nearly the same time. (Lesson 18.) The difference
their periodic times is Dot greater than might result from
the supposed disruption, as the parts thro~DforZDard would
have their motion accelerated, while the other parts would
be thrown back or retardBd;. thus changiog the periodic
times of both.
( 4.) The great departure of the orbi18 of the A steroids
(rom the plane of the ecliptio is supposed to favor the
hypothesis of their having been originally one planet, the
assumption being that the explosipD separating the ori.
ginal body into fragrnenta would not only accelerate some
portions and retard others, but would also throw them out
or
---...,
157
OI.IGIK OP THB AS'I'BI.OIDS.
of the pI ane of the original orbit, aod in some cases still
further from the ecliptic.
(5.) Thei}\ orbits are more eccentric than those
the
other primaries, (46.) Although the table shows the
eccentricity of Herschel's orbit as greater in miles than
that of even Juno or Pallas, yet when we coDsider- the
difference in the magnitude of their orbits, it will easily
be seen that his orbit is less elliptical than theirs. (6.) The orbits of Ceres and Pallas, at least, cr08' eacl
other, as shown in Map 2. This, if we except perhaps
the orbits of the comets, is a perfect anomaly in the Solar
or
8ystem~
From all these circumstances, it has been concluded
that the Asteroids are only the fragments of an exploded
world, which have assumed their present Corms &iDce the
disruption, in obedience to the general laws of gravitation. This theory of Dr. Olbers, is favored by Pror~
Nichol, Dr. Brewster, Dr. Dick, and others; while Sir
John Herschel observes tha-t it may serve as a 8pecimea
of the dream, in which astronomers, like other speculators, occasionally and harmlessly indulge.· Dr. Dick
remarks, that the breaking up of the exterior orust of the
earth, at the time
the gelleral deluge, was a catastrophe as tremendous and astonishing as the burstin,
asunder of a large planet.
_
The late General Root, of Delhi, was of opinion that
the Asteroids were primarily,atellite, c!f Mar, j which,
as if dissatisfied with their low oondition as mere attend.
ants upon anotber, and one, too, not lQuch larger than
themsel ves, ha va wandered from their original spheres,
and assumed the character of primaries. The rea.01I8 for
this opinion, 8S stated to the author by Gen. Root, in the
fall of 1846, are quite as satisfactory 88 the evidences by
which the theory of Dr. Olbers is supported. But this is
Dot endorsing either the one or the other. Indeed, in view
the karrrumyand order that everywhere reign throughout t he planetary regions, directing the pathway and CODtrolling the destiny of every world, it is hard to believe
or
t
-
or
• Treati_, p. Ita
t Ce1_ial SceneryJ p. 140
14
-
158
AIlB TBB PLANBTS lNBABITBD'
tbat any planet has either been broken to pieoes by SOlll8
mighty explosion or concussion, or wandered from its
presoribed path into a Dew and esaeotially different orbiL
Lesson I ItI.
I
..lRB THB PLANBTS INHABITED BY RA. TIONAL BEINGS 1
U poD this intereating question, it must be admitted,
that we have no positive testimony. The argument in
tbe affirmative is baaed wholly upon analogies, and the
'conclusion is to be regarded ooly in the light of a legitimate inCerence. Still, it is remarkable tba.t those who
are best acquainted with the facts
.astronomy are
most confident that other worlds, as well as ours, are the
abodes of intelleotual life. Indeed, as Dr. Diok well remarks, it requires a minute knowledge of the whole
aceoery and circumstances connected with the planetary
system, before this truth comes home to the understand.
ing with tull conviotion.
It is ·Dot proposed, in this lesson, to discuss at lengtltbe question of a plurality of worlds, but merely to give
the beads of tbe arguments by which this doctrine is
8Upported, leaving the reader to amplify them by reflection, or to pursue the inquiry, at his leisure, in more
elaborate works. Perbaps no ~riter hu done better justioe to this subject than Dr. Dick,· to whom we are in.
debted Cor many of the arguments with which this lesson
is enriched.
.
1. The planets are all ,olid bodie, resembling the
eartb, and Dot mere clouds or vapors.
. 2. They all ha va a aplierical or .,1&,roidal figure, like
our own planet.
3. The laws of gravitation, by which we are kept upon
the surface of the earth, prevail upon all the other planets,
as if to bind races ot material beings to their surfaces, and
provide tor the ereotion of habitations and other conveniences of life.
or
• Celedial Scenery, pp. 331-363
159
ARE THB PLANBTS INlU.BITB'D 1
4. The magnitude, of the ,lanets are such as to aWord
ample sQOpe {or the abodes 0 myriads of inhabitan,ts. It
is estimated that the solar bodies, exclusive of the comets,
contain an area of 78,000,000,000 of square miles; or
397 times the surface. of our globe. According to the
population of England, this vast area would afford a resi.
dence to 21,875,000,000,000 of inhabitants; or 27,000
times the population of our globe.
5. The planets have a diurnal re"olution around their
axes, thus affording· the agreeable vicissitudes of day and
night. Not only are they opaque bodies like our globe;
receiving their light and heat from the 8UD, but they also
. reTolve. 80 as to distribute the light and shade alternately
over each hemisphere. There, too, the glorious SUD
arises, to enlighten, warm, and oheer; and there "the
sun.strown firmament" of the more distant heavens i.
rendered visible by the no less important blessing of a
periodic night.
It is very remarkable, also, that those planets whose
bulks are such as to indicate an insupportable attractive
force, are· not only less dense than our globe, but they
have the most rapid daily revolution; as if by diminished
density, and a strong centrifugal force combined, to re.
duce the attractive force, and render locomotion possible
upon thei r surfaces.
6. All the planets have an annual re"olution round the
sun; which, in connection with the inclination of their
axes to their respective orbits, necessarily results in the
production of seasons.
7 . The planets, in all probability, are enveloped in atmosphereB. That this is the cale with many of them is
certain; and the fact that a fixed star or any other orb
is nbt rendered dim or distorted when it approaches their
margin, is no evidence that the planets have no atmosphere.. This appendage to the planets is known to vary
. in density; and in those cases where it is not detected
by its intercepting or refracting the light, it may be of a
nature too clear and rare to produce such phenomena.
8. The principal primary planets are provided with
moons or 8atellite8, to afford them light in the absence of
•
160
.AU 'fBB PLANBTS INBA.BITBD'
the 8un. It is Dot improbable that both Mars and Venul
bave each, at least, one mooD. The earth has ooe, and
as the distances of the planets are increased, the Dumber
of mOODS seems to increase. The discovery of only six
around Herschel is no evidence that others do not exist
which have Dot yet been discovered.
9. The surfaces
all the planets, primaries as well
u secondaries, seem to be variegated with Aill
dt&le,
With mDrInUJira and plain.
Every Fart of the globe we inhabit is destined to the
IUpport 0 animal life. It would, therefore, be contrary
to the analogy
nature, as displayed to us, to sup~
that the other planets are empty and barren wastes, utterly devoid of animated being. The inquiry pre_es
itael f upon the mind with irresistible force, Why should
this one small world be inhabited, and all the reBt unoc.
oupied 7 For what purpose were all these splendid rmd
magnificent worlds fitted up, if not to be inhabited 1 Why
these days and years-this light and shade-these atmo.pheres, and seasons, and satellites, and hill and dale 'I
The legitimate, and almost inevitable conclusion is, that
our globe is only one of the many world. which God haa
oreated to be iohabited, and which are now the abodes
bis intelligent oftSpring. It is revolting to suppose that
we of earth are the only intelligent subjects of the
" GRBAT KING," whose dominioDs border upon infinity.
or
au
or
or
i
I
•
I
i
I
PART II.
THE SIDEREAL ·HE! VENS.
,
CHAPTER I.
'
OP CONSTELLATIONS OF STAKS.
Lesson 113.
DISTINGUISHING CHA.RACTERISTICS OP THB PIXBD STAllS.
Sidereal Heavens embrace all those celestial bod.
i"a. that 'lie around and beyond the Solar System, in the
region of the Fixed Stars.
'
The l?ixed Stars are distinguished from the Solar Bodies
by the following characteristics :
1. They shine by their DUm light, like the SUD, and not
by reflection.
2'. To the naked eye they seem to' t7Dinkle or scintil.
late; while the planets appear tranquil and serene.
3. They maintain the same general positiDn8 with re.
.pect to each other, from age to age.
' "
,. They are inconceivably diatant, 80 that 'When view..
ed through a telescope they present DO sensible disc, but
appear only as shining points on the dark concave of the
THE
•
,
.
t
sky.
.
.
To these might be added several other peculiarities
which will be noticed in the seq uel, but they are not no-
"oessary to our present purpose.
Lesson 116.
or. THE
,,(Map 16.)
CLASSIFICATION
STAllS.
For purposes or convenip,nce in finding or rererring to
particular stars, recourse is had to a variety
artificial
14'"
or
162
CLASSIFICA.TION OF THE STA.IlS.
Dlethods of claasification, with which the pupilsbould here
become acquainted. .
1. The whole concave of th~ heavens is divided into
IeCtions of greater or less ext~nt, called C0f&8tellat:ioru.
~'or the origin of these most uDnatural and arbitrary divisioDs, consult Lesaon 36. A list of the constellations
will be fouod in a subsequent chapter.
2. The stars are all classed according to their magaitude.. There are usually reckoned twelve different
magnitudes, of which the first six only are visible to the
naked eye, the rest being telucopic
This magnitude, of course, relates only to their apparent brightness,
88 the faintest star may appear dim solely on account of
ita immeasurable distance.
Fig. A on the map is a representation of the first eight
lDagnitudes, the two smallest of which will be invisible
to the pupil at a distance. " It must be observed," says
Dr. Herschel, "that tbis classification into magnitudes is
entirely arbitrary. Of a multitude of bright objects, difrering, probably, intrinsically both in size and in splendor,
and arranged at unequal distances from us, one must of
necessity appear the brigbtest; the one next below it
brighter still, and 80 on."
8. The next step is to classify the stars of eack COMtel
laticm according to their magnitude in relation to eacA
other, and without reference to other constellations. In
this classification the Greek alphabet is first used. For
instance, the largest star in Taurus would be marked (a.)
Alpha; the next largest (~) Beta; the next (r) Gamma,
&c. When the Greek alphabet is exhausted, the Roman
or English is taken up; and when these are all absorbed,
recourse is finally had to figures.
4. To aid still further in finding particular stars, and
especially in determining their numbers, arid detecting
"hanges, should any occur, astronomers have constructed
Cata/.ogtJU of the stars, one of which is near 2,000 yean
old.
5. Several of the principal stars have a specifio name
like the planets; as Siriua, Aldebaran, Regula, &c.
6. Clusters of stars in a constellation sometimes
. re-
.tar..
I
163
KVIIBBa OP TBB paEl) &TAIlI.
ceive a specifio name, as the PleiGdu and H,atlu iD
Taurus.
7. The stars are still Curther distinguished into Dou ble,
Triple, and Quadruple stars; Binary System; Vatiable
Stars; Periodic Stars; Nebulou8 Stan, &c.; all or
which will be duly Doticed as we proceed. But we must
the 8tarry
first consider the more general divisioDs
heavens.
or
Lesson 117.
5VMBBB. OF THB PIXBD STABS.
The actual number of the stars is known only to Hi..
who" telleth the number of the stars," and " calleth them
all by their names. JJ The powers of the human mind are
barely sufficient to form a vague estimate of the number
Dea~ enough to be aeen by our best telescopes, and here
our inquiries must And.
The number of stars down to the twelfth magnitude,
has been estimated as follo\vs :
18
1st magnitude,
Visible to
2d"
02
3
d
"
177
the naked
4th"
376
eye,
5th"
1,000
6th"
4,000
5,628
7th
26,000
"
u
8th
170,000
Visible
9th
1,100,000
"
only thro'
7,000,000
"
tel 'scopes, 10th
11th
46,000,000
"
12th
300,000,000
"
354,296,000
Total number, 854,301,628
Orthese stars, Dr. Herschel remarks that from 15,00(1
to 10,000 or the firAt seven magnitt:des are already, regu•
• red, or DOted down in catalogues; and ProC. Olmated
164
DIITANC.B8 OP TUB STABI.
observes that Lalande haa registered the positions or no
less than 50,000.
" If we suppose," says an eloquent writer, "that each
or these SUDS is accompanied ooly by as many planets as
are embraced in our Solar System, we have _fifJ6 t/unu"nd,
",illio'M of tDOrlU in our firmament. No human mind
can form a conoeption or this number; but even these, as
will hereafter be shown, form but a minute and comparatively insignificant portion of the boundless empire which
the Creator has reared, and over which he reigns. EterDal ages may glide joyfully along, as the Christian explores these wonderful worlds; of every variety of form
and character, and partakes of the hospitalities of their
blissful inhabitants. I t is pleasant to tread the pavements
of a foreign citY-1n traverse the glaciers of the Alps-to glide over the surface of the Nile in the midst of the
mouldering remains of its past grandeur; but what are
all these, compared to the journey of a rejoicing spirit to
these sublime mansions of the Deity 1"
Lesson lIS.
DISTA.NCES OF THE STA.RS.
It has been demonstrated that the nearut of the
~
stars cannot be less than 20,OOO,OOO,OOO,OOO-ttDtnty
billi0f&8 of miles distant! For light to travel over this
space at the rate or 200,000 miles per second, would require 100,000,000 seconds, or upwards of three years.
What then must be the distances of the telescop~o
stars, of the 10th and 12th magnitudes! "If we admit,"
says' Dr. Herschel, "that the light of a star of each magnitude is half that of the magnitude next. above it, it will
follow that a star of the first magnitude will require to
be removed to 862 times its distance, to appear no largeJ
than Olle of the twelfth magnitude. It follows, therefore,
that among the countless multitude of such stars, visible
in telescopes, there must be many whose light has taken
at least a thousand years to reaclI U8; and that when we
observe their places, and note their chan2es, we are, ill
KJ.GNITUDB OP TBB STAB••
165
ract, reading only their history oC a thousand years'
date, thus wonderfully recorded.'~
Should such a star be struck out oC existence now, its
light would continue to stream upon us Cor a thousand
years to come; and should a new star be created in
those distant regions, a thousand years must pass away
before its light could reaoh the Solar System, to apprize
us of its existence.
Lesson 119.
•
MAGNITUDE OP THE STABS •
.,. From what we have already said respecting the almost
Inconceivable distances of the fixed stars, it will readily
be inferred that they must be bodies of great magnitude,
in order to be visible to us upon the earth. It is probable,
however,' that "one .star ditTereth from another" in its in•
. . trinsic s'pleDdo~ or "glory," although we are not to infer
that a litar is comparatively small, because it appears
small to us.
The prevailing opfnion among astronomers' is, that
wha.t we call the fixed stars are so many BUU, and
oentres of otber systems. By a aeries of experimeots
upon the light rece~ved by us Crom Sirius, the nearest of
the fixed stars, it is ascertained that if the IUD were removed 141,400 times his present distance from us, or
thirteen billions of miles, his light would be no stronger
than that of Sirius; and as Sirius is more than twenty
billions of miles distant, he must, in intrinsic magnitude
and· splendor, be eqUfll to two S\1D8 like ours. Dr.
Wollaston, as cited by Dr. Herschel, concludes tbat this
star must be equal in intrinsic light to nearly fourteen
8UD8 f
According to the measurements
Sir Wm. Herschel,
tbe ·d~ameter
tbe star Vega in the Lyre, is 38 times
that
the sun, and its solid contents· 54,872 times
greater! The star numbered 61 in the Swan, is estimated to be 200,000,000 miles in diameter.
Sir John Herschel states that while making observa.
or
or
or
166
LIST OF TO CONSTB.LU.TIONS.
.y.
tions with his forty.feet reflector, a star of the first magnitude was uninteotionally brought into the field of view.
" Sirius,"
he, "announced his approach like the
dawo of day j" and 10 great was his splendor when ~U8
viewed, .and 10 atrong W88 his light, that the great astrooomer wu actually driven from the eye-piece of his
teleecope by it, 88 if the SUD himself had suddenly burst
upon his view. He was obliged to employ a coloted
screen, as in the case ot solar observatioDs, to protect bis
eye from the strong and glowing radiance.
According to Sir W m. Herschel, the relative light of
the stars of the first six magnitudes is as follows:
Light of a star of the a verage 1st magnitude 100
"
"
"2d"
2.'i
"
"
"
"
"
"
"3d"
"4th"
"5th"
"
"
"6th"
1~
6
2
1
Lesson 1 "0.
LIST OF THE CONSTELLA.TIONS.
Of the natUN and orWi" of the constellatioDs we have
already spoken in LessoD 36. Their Cormation has beeD
the work of ages. Some of tbem were known at least
8 t OOO years ago, and bore the very names by which they
are known to this day. In the 9th chapter of Job we
'read of " Aroturus, Orioo, and Pleiades, aDd the chambers
of the BOuth ;" and in the 38th chapter of the same book,
it is asked, "Canst thou bind the sweet influence8 of
Pleiades, or loose the bands of Orion 1 Canst thou bring
forth Mazzaroth in hi, _&sOn 1 or caoat thou guide
A rcturu8 with his sons '"
: At first tb•. number of constellations was few. Being
found convenient in the study of the heavens, new; ODes
were added to the list, composed of stars not yet made
up .1oto hydras and dragons, ~ill there is now scarcely
stars or room enough left to coDstruct the smallest ne"
constellation, in all the spacious heavens.
167
CONSTBLLATIONS.
The constellations are divided into the Zodiacal, the
NlWtAern, and the Southern.
The Zodiacal C0f&8teilatiou are those which lie in the
Bun'S apparent path, or along the line of the Zodiac.
See Leason 86, and the map.
The Northern COMtellatiou are those which lie be.
tween the Zodiacal and the North Pole of the heavens.
The Southern Constellati01I.8 lie between the Zodiacal
. and the South Pole of t.he heavens.
The oonstellations are also distinguished into ancienl
and modem. The following is a list of all the constelJations, both anoient and modern, with the number of principal sl.ars in each, according to Ptolemy's Catalogue,
and al_\1 that of the Observatory Royal of Paris.
I.
ZODIACAL CONSTELLA'l'IONS.
Latin Dam••
1 'f AR.I ...
JJ ~ rAuaua.
3 .0
GBM1NI.
En,lilh nam..
Th.e Ram.
The Bull.
Tltt~ T1Din...
.. ~ CANCBL
T}It~
5 £'\. Lao.
ft rfJl V111.00.
The
Tht!
"I 6
8 f11.
L,BRA.
T"~
SCOR.PIO.
Th«
Tht
Th«
Tht
Th« Ful&tl,.
9
10
11
11
I
SAOI'M'Akb'"
~ CAPlUOOKI'!.UIL
=
*
AQl1AR.lbli.
fJM:l: ..
Crab•
Lion.
l"irgin.
Sr.al«.
Scorpion.
Archer.
Goat.
Water-Ntlrer.
Ptol',. Ob. L
18
~
44 t07
25
33
&4
85
3~
93'
117
67
60
94
64
117
118
32
07
27
31
fI8
45
38
II.
NORTIIERN PONSTELLATloNS. ·
ANCIENT •
13 U..A MIKOL
14 UIlM MAJOR.
15 Duoo.
16 CI:PUI:w.
1'1 BooT...
. 'I'M Little B«ar
08
II
T 1&« Gr,at BtGr.
Th, Dr• •,,-
34
87
81
13
23
86
58
C«pJuu.
Boot,..
70
/'68
CONSTBLLA.TION5.
LaUta ........
18
19
20
En,liah a&lD8I.
TUAIIG. BollaAI••8.
Th, N(Jrth~rn Crown.
Hwcvl,••
Tl, Harp.
T'" SVJtJ1f,.
CfI,nop'",.
Pn-.,u.
Tl, ChtJriotter.
TM S,rpent-b,ar,r.
Tk, Arrow.
The Eaglt.
Tht Dolphift.
TA, Littl, Hortle.
PtgaftJ'.
Antineru.
Andromeda.
TAe NortA. TNn,.
COilA B.alllno_ .
B..,·,,"c,'. HtJIf'.
CoRONA 80aBLIIL
H.acuLa..
LYRA.
~l CYGNUII.
22
CAMior.IA.
~ PBUBU8.
24
AURIGA.
25
26
27
O'HIUCBt1L
18
DELPHINUe.
29
30
EQUULRUB.
31
ANTINOU&
32
33
34
ANDROIIBDA
SAGITTA.
AQUIlA.
•
P.OA_va.
Plol'l.
08
29
Ob."
33
128
21
10
85
10
13
29
14
29
05
15
10
04
20
15
23
04
35
60
65
69
61
18
26
19
10
91
28
71
15
43
.00 II 8.N.
~ CUI'f08 M_luII.
TI&e Liul, Lioft
Tie Grey!&QURtU
TI&e Sezttl1lt
Cer6eru...
PonitJt01lJ,lci, Bull.
TAe Foz lind 000• .
TA-e Lisard.
Th, Littl, TrilJngk.
Ti, Northern Fl,.
Tie Reindeer.
The Ha.rve.tn-.
46
CAIiBLOPAaDALU"
T~
"
LIla.
35
Lao MINOL
36
CAN.8
37
SRITAIf..
38
39
CBRB.aUB.
V BNA'I'IOI.
TAUILU8 PONIATOW8U
40 VBLPRaULA
41
a,. An.
LAoaaTA.
~ TalA.NGULA MDfOU.
43
MUIIOA Do.SALIIL
"
TAaANDU&
56
38
54
13
18
35
12
04
05
Ii
07
69
CtJmelopartJ
TIN Lynz.
45
III.
S(lUTBERN ~()NSTELLA TIONS.
ABel.lIfT.
48
e
C.,.t1L
EaIDA.1'W&
TIN WAllie.
TIN RiDer Pe.
"
19
34
1.
81
;'
169
aoKft&LL.A.'lJOXI.
La....__
!O Ouo••
.
61 Law.
61 C. . . MmoL
13 C.... Muoa.
"Auo
65
N~...
BYD. . .
16 CUT...
57 Coan..
58 C&Jft'Auaa
59·LuJw.
&0 Aa~
61 CoaoRA Au.raALI&
•
~PuIola
AU8ftALIJL
,,1iI1a .....
PloI ...
ab."
Orion.
TA. Har••
3e
Ii
SO
Tie Little Dog.
og
17
TA. (hea' Dog.
TAe 81i, Argo.
Tie Water S.,.,..t.
I'll C.,.
Tie Oro",.
Tie e••tGw.
TAe Wolf.
7'1. Alt"r.
Tie 80utlena Cro.,..
TJu 80utlunt F'-l.
19
45
54
07
10
48
90
117
WI 5i
07 13
37
19
07
34
08
13
Ii
18
24
The CA..it:. Pu,.,..
TIe RAMI,bed N.t.
Tie B"f'rfJ"'!'"'- TooL
TM ~u"".tl-.fi.A.
TAe DOfJe.
TIe Painter', Ba,L
TAe Unicom..
Th, Mariner'. COfIIptI& Tile Air-pump.
Th, SolittJry Bird.
The Southern Cro".
'l'Ae SoutAn-n Fly.
Tie CIuJ""leora.
TM Flying-ful.
Tlu Te~e.co~.
TIe Pe"dlJ,~IJ"', fc:.
Euclid', Square.
TM Compa"e,.
Th, SoutAI'm TriGftgle.Tie Bird of ParGdUe.
.nnt of Table Ba,.
8olM.k,'. BIa.tIe
39
MODERB.
G Fouru CmmoA.
"
15
I
.
Rft'lOVLI8 Ruo. . .
C.L& SOULrrOU..
XrPIL
66
67
68
EQVUL&U8 PlOT.
69
MONOCB&08.
70
11
71
13
14
15
76
77
18
19
80
81
82
83
84
PYx.. NAU'I'IOA.
AUTLIA PN&VJlAT.
Ana SOLl'l'.
Cavx AU8TL\LI&
MWCA AU8TULItI
Do...DO VaL
COLOIOA NOACBI.
CB~ •• L.ONI&
Pilei.
VOLUl..
T&LUOOPIUK.
I
HOROLOGIUII.
NORllA
EuOLID. .
Claollwa.
TaJAlfa. Au.,.."'.
Ap. ftL Ay.I.DICA.
Mo. MaM8ouft. a.......
85UD1J8
86 PAYO.
-
TAl 1""__
Tie P4tMJOCi.
15
--
07
15
08
Oi
04
31
14
~
•oa
04
07
06
08
23
15
Oi
05
CM
oa
18
04
11
170
...
OP TUB P.1lI01P.A.L OOlISDLLATIOlfS.
n.
ftoFL Ob. a.
-~
OettIrtL
-
07
08
12
11
88 Mroll.OllOOftUJL
BIG...
TIe.~.
90 TovoJWlf~
TA. A.er. Goo...
TIe W.",......k..
- . 08
Tie ScalptGr'. SttuJio.. 18
11
Tie PJuaJlis.
TIe Cr. . .
91 BuaUII.
n
APP~&A'l'U8
Souu.
91 PaabtJL
-
RECAPITULATION.
Zodiacal eon.tenaticms, 12
Northem"
35
Southern"
46
Principal stars,
"
"
"
Total, 3706
Total, 93
Lesson
c,
1125
1531
1050
1~1.
DBSCJUPTION OF SOU OF TBJ: PRINCIP....L CONSTBu..TIOllS.
Although this work is designed particularly to Ulo8trate the Mechanism of the Heavens, as displayed ill the
Solar System, we are desirous of furnishing the learneJ
with a sufficient guide to enable him to extend his inq oi.
ries and investigations, not ooly to the different cltU8U
of bodies lying beyond the limits of the Sola"r System, in
the far-off' heavens, but also to the Con8tellations as such.
For this purpose we shall here furnish a brief description
of the principal constellations visible in the United States,
or in north latitude, by the aid of which the student will
be a.ble to trace them, with very little di~cu1ty, upon "that
glorious celestial atlas· which the Almi~,hty bas apreari
,out before us.
These des9riptiool are partly original, and partly from
the writings of Olmsted and Burritt. .
ZODIA.CAL CONSTBLLA.TIONS.
The Constellations or the Zodiao, succeeding each
other in "regular order ea8tward, and being more eMily
found OD that account than others, should first be studied_
.171
ABIB' is a email constellation known by two bright
about 40 ..part. which form the head. The brightest is the moSt northeasterly of the two.
.
.
·rAt1R17S will' be readily found by the seven stars or
Pleiades, which lie in' his' n·eck .. The largest star in
Taurus is Aldebaran; in tfle Bult's eye, a "tar of the first
magnitudet of a' reddj.ah .color, somewhat resembling the
planet Mars. AldebaraD, an4 four other stars in the face
of Taurus,. oo~pose the HJad,u. They are 80 ,placed lUI
to form the. lelter V.
GBMINI is known by two very bright stars, CtuIDr a~d
Poll~, about five degtees apart.
CA.NeB. is lees remarkable 'than any other oonstellation
of the Zodiac. It has DO stars larger than the third mag.
nitude, and is ~istinguished (or a group or small stora
called the Nebula of Cancer, which is often mistaken for
a comet. A common telescope resolves this nebula into,
a beautiful 8ssembl,age of bright stars~
LEO is a large and interesting constellation, contain.
ing an unusual Dumber: C?f'. very brigbt stars. Of these,
RegulU8 i~ of the first magnitude, and .lies directly in the
ecliotio. North of Regulus are several',bright stars in
the form of a siclde, of whioh Regulus is the handle.
Denebola is a bright star of the second magnitude, in the
Lion's tail. It is about 250 Dorthe~8t of Regulus, and
350 west of Arctur.us. .
V I1I.ao extends for I01Jle .distance {rom west to east,
but contains only a few bright atars. ' Of these, SpiOll. in
the ear or corn which the Virgin holds in her. left hand,
ill a brilliant star of the first magn~tude. The rest 01
Iler principa.l stars ~~ of 'the third and fourth magllitudes.
,
IItars,
may be known by its four principal stars, form.
ing a quadrilateral figure. The two brightest ~f these
constitute the beam of the balanoe, and the slnaU(;st is in
the top or handle. .
ScoaPIo is one of the moat interelting and splendid of
LIBRA
J72.
BOaTB&mf COlfITBLUftOX••
tbe conltellatioDs. His bead coll8ists of five bright stan,
forming the arc of a oirole, and is croSled by the ecliptio
near the brightest of the five. Nine degrees lOutheaat is
the star AftltJru, or a reddish color, and oC the first magnitude. A number of small &tara that curve around
towards the east constitute the tail oC Scorpio.
8AGITT.A.B.1118 lie. next to Scorpio, and may be known
by three stan arranged in a curve, to repreeeDt the 60111
of the Archer, the central star being the brightest, and
baving a bright Itar directly west of it, fOrming the head
the GrTOIfJ.
or
"-
lies northeast of Sagittarius, and may be
IE nown by two bright stara c10a.e togetlaer, which 00DSti.
CAPJUCOJlNUS
I
tute the bead.
AQU'AJlros is represented by the figure of a man pour.
ing water out of a vessel. Its Cour largest stars are
tbe third magnitude. Two of these, which lie in a liDe
with the brightest stars in Capricomus, constitute the
head of the figure.
or
the last of the Zodiacal constellations, lies be.
tweeD Aquarius and Aries. Tbe Southern Fish coosists
of 24 visible stars, of which one is
the first magnitude,
two of the third, and five of the fourth. The remaining
16 ale smaller. The. largest star is situated in the
mouth of the Fish, and is called POfIUJ,lAaut. The
Northern Fish coosists. wholly of small stars, and is coo.
neeted with the Southern by a aeries
stan CormiDa a
.
PISCBS,
or
CI'OOkeclline betweeD them.
or
Lessen 1 •••
.
IfOKTDJUf CONSTBLllTIOX••
bei,
The Constellations or the Zodiac
first well
learned, 80 as to be readily recognised, will aeUitate the
leaming of others that lie north and loutA or them. Let
us, therefore, review the principal Nordae,.,. Cou6Jlla.
•
l
IfOJrDlJ&B.R C8JfITBLllTJ01f8.
tiou, beginning north of ·Aries and proceeding {rom west
to east.
or
ANDROMEDA. . may
be known by three stars
the
second magnitude, situated in a straight line, and extend.
ing from· east to west. ;The figurp is that of a "Woman,
with her ar. . est8nded; aad chaiaed by. her wrists to a
rook. The middle Itar, of the three just Darned, is .
situated in her ginlle,. and is called Mirach. The one
west of Miraoh i. in Ute 1IelJIl, of Andromedat aD4 . the
eastern one, called Almaak, is in her left fooi. The star
in her hea4 Is in the Eq uinocthil Col ure. The three
largest stars in this constellation are" of the secondm\agnitude. Near Mirach are two stars of the third and
fourth magnitudes, and the three in a. row cons~itute the
girdle. .
The loose assemblage of ~man stars directly souih of
Mirach, are the Northern Fish, alraady describ~d . .
lies directly north of the Pleiades; and east
of Andromeda. The ~ure is that of a man with a
sword in his right hand, and the he'ad of Medul& in hi.
left. A bout 180 from the Pleiades is Algol. a star of the
second magnitude, in the head of Medusa; and 90 . north.
east of Algol' is .A~ef&i1J, of the same magnitude, in the
back of Perseua. It bas, also, {our stars of the third
magnitude.
.
Algol will be mentioned again, under the head·
Variable Stars.
PBXSB11S
or
A lJRIGA. ( The Wagoner) is the figure of a man in a
declining posture, resting one foot upon the hot-n of Taurus. It is nQrth of Taurus and Orion, and directly east
of Perseus. Capella, the principal star in this constella.
tion, is one of the most brilliant in the heavens. It is in
the west shoulder of Auriga, and may be known' by a
·
small triangle near it, formed by three small 8t~rs.
The LYNX comes next in order, but presentp bothing
particularly interesting, as it contains no stars abt>ve the
fourth magnitude, and even" theie are scattered over a
•
15*
----- -- --1
174
KOaTIIBJUf COJISTBLLA.T10lfl.
or
large apace north
Gemini, and between Auriga and
Ursa Major.
LBO MINOR is oomposed of a fe~ small stars lying between the sickle in Leo, and the Great Bear.
COMA.. BBllBNICBS i. a beautiful cluster of small stars,
Dorth of Denebolis; in the tail of the Lion, aDd north 01 the
head of Virge. It has but ooe star as large 88 the fourth
magnitude. Cor Caroli, or Charles's Heart, is a bright
. r about IjO direotly north of Coma Berenice••
or
is the figure
i. man ~ith a olub in his
right hand, with" which he seems to be driving the Great
Bear round the pole of the heavens. He is thence called
the Bear Driver. -ARCTURUS, situated near the left knee,
is a star of the 'first magnitude, and of a reddish color.
He is accompaDied by three small stars, (his" sons, "*)
which (arm a triangle a littl-e to the southwest. A star
of the 'second magnitude is in the head of the figure, and
two bright stars of the third magnitude form the shouldel"8.
CORONA. BOB.BA.LIS (The CrOfDft) is situated betWe8D
Bootes on the west,' and Heroules on the east. It CODlists of six prinoipal stars, in the form of a wreath 0)
BOOTBS
j
I
OroWD •
.Alpk4t;ca, the largest star or the group, is of the third
magnitude, and may be known by its position in the cen.
tre of the crown, as well as by its superior brightness.
HERCULBS lies immediately east of the crown, and occnpies a large space in the Northern hemisphere. The
.figure is that of a giant, with ,a large olub in his right
hand. The head is towards the south.
This constellation is thickly set with stars, the largest
which is called Raaa/gethi, in the head of the figure,
and is or the second magnitude. It has nine stars of the
third magnitude, and nineteen or the (ourth.
or
OPBIUcltuS ( TM Serpene.1HJtlrtr) is situated direcdy
lOuth of Hercules, with its centre nearly over the equ~
tor, and nearly
opposite to Orion. The figure
i. that
,
.
or.
• Job uniiL 31.
NOB.TBBJU'f CONSTBLL.l.TIONS.
1 7fJ
yeuerable-looking mao, grasping a serpent in hi' hand.,
the lead of which consists of three bright stars, situated
• little south of the crown. The fouu of the serpent may
be traoed by a succession of bright stars extending for
aome distance to the east.
The principal star in Ophiuchul is of the second magDitude~ and is called ~ Al1aague. It is situated in the
Aea.tl of the figure, and within 6 0 of Rasalgethi, in the
head of Hercules.
(The Eagle) is conspicuous for three' bright
stars in its neck, of which the central one, Altair, is a
brilliant white star or the fiNt magnitude. Antinoa lies
AQUILA
directly south of the Eagle~ and nonh of the head of
Caprioomus.
DELPBINU~'
(The Dolphin) is a beautiful little cluster
of stars, a little to the ·east of the Eagle. It may be
known by rour principal stats in the head, of the thi~d
magnitude, arranged in the figure of a diamond, and
pointing northeast and south west. A star of the same
magnitude, about 50 south, makes the tail~.
is a large constellation situated between the
Dolphin and Eagle, on the west, and Andromeda aD~ the
Northern Fish, on the northeast. The figure is that of a
winged hqrae, in an inverted posture. It may be known
by four stars about 160 apart, forming a 8quare called the
square of Pegasus. They are of the second and third
magnitudes, and one .of them, viz. .A~enib, bears the
same name as a star in Perseus:
PBGASl1S
or
The HORSE'S HEAD is a small cluster ot stars, w~si
the head of Pegasus, and about half way to the Dolphin.
It contains ten stars, of which the rour principal are only
of the fourth magnitude. They form a long irregular
sq uare, the two in the DORf? being 10 apart, and those in
the ey~s 2lo. These four stars are about 10 southeast
of the diamond in the bead of the Dolphin., ,
We
DOW
come to notice the constellations around the
176
lf01lTJlBJlK CO~LLATIONS.
North Pole, and which are always above the horizon in
llorthem latitudes.
(TM LiIJk B84r) is Dear tb. north pole
of the heavens. It cODsiRts of the Po~ &ar, 88 it is oall.
ed, which CorlD8 the extremity of the tail, aDd six other
principal &tan, three of the'third, and four of the fourth
magnitudes. The se.en together are arranged in the
Corm of a dipper, with the Pole Star in the end of the
Uau
MINOR
handle.
URSA M.vOB
(7'118 Great Bear) may be known by the
figure of a larger dipper, which constitutes "tbe hinder
part ot the animal. This dipper, also, is composed
seven stars. The first, in the end of the handle, is called
BenetfuJ8A, and is of the second magnitude. The ne:Kt is
Mizar, known by a minute star almost touching it, called .
Alcor. Mi~aT is a double star. The third in the haudle
is Aliot". The first star in the bowl of the dipper, at the
j unction
the handle, is Megrez. Passing to the bottom
of the dipper" we find Phad and ¥erak, while Dubhe
forms the rim' opposite the handle~' Mer~ and Dubhe
are called the Pointer.;, because they always point towards the Pole Star.
.
The head of the Great Bear lies far to the west of the
Pointers, and is ~poeed of numerous amall stare; while
the fB~t are severally composed of two 8Dlall stars, very
near to each other.
or
or
Duco (T1te Dragon) f'compasses a large circuit iD the
polar region.. He winds round between the Great and
Little Bear, and commencing with the tail, between the
Pointers and Pole Star, it is easily traced by a succession
of bright stars extending from west to east; passing under
Ursa Minor, it retutns westward, and terminates in tour
stars which torm the head, Dear the foot of Hercules.
These four stars are 3°, 4°,~nd 50 apart, 80 situated as
to form an irregular square; the two upper ones being
the brightest, and bdth" the second mag"nitude.
or
or
'ies east of th~ b~east
Draco, but has n '
Itare above the seco)Jd magnitude. "The figure is" that ~
CEPHEUS
IOUTD. . OOKSTBLUTlOK8.
177
a iing, crowned, and with a sceptre in his left hand,
which is extended towards Cassiopeia.
is a queen on a throne or ohair, with ber
head and body in the Milky Way. The chair is composed of four stars, whioh form the legs, and two consti.
tuting the back. Five of these are of the third magnitude.
CASSIOPBIA.
LYIL&
('lle Lyre) is distinguished by one of the bright-
est stars in the northern hemisphere. It is situated eut
of Hercules, and between' him and the Swan. Its largest
star is Vega, or Alpha Lyra, and is of the first magnitude..
It has two others of the second magnitude, and several
of the fourth.
(The StDafl) is situated direotly east of Lyra.
Three bright stars, which lie along the Milky Way, form
the body and 'leek of the Swan; and two oth~rs, in a line
with the middle one of the three, constitute the tDifl81.
1 t bese five stars form a latge cr088.
.
Arided, in the body 'Of theS'wan, is a star of the first
magnitude~ and the .remaining o!les of the constellatioD.
are of the third and fJurth magnitudes.
CYGNUS
CA14ELOPARDALUS
(The Camelopa'lJd) is alar ge and
UD-
interesting field of small stars, scattered between Perseu..
Auriga, the head of Ursa Major, and the Pole Star. Ita
five largest stars are only of the fourth magnitude, the
principal of which is in the thigh. The head of the ani.
mal is near the pole.
The LYNX also is composed' of small 8tars; scattered
over a large extent. It lies north of Gemini, and between
A.uriga and Ursa Major. Its three largest stara are ot
the third magnitude.
MIiSOD 1~3.
SOUTHERN CONSTELLATIONS.
The Southern Constellations art' comparatively few,.
Dumber, though lOme of them are very beautiful.
1~8
MOT_aN COftSDLLA'ftON8,.
(7Ie Whale) i. tbe largest constellation in the
heavens. It is situated below or 80Uth of .Aries. It is
represented with its bead to the east, and extends 500
east and west, with an average breadth of 20°.
The head of Cetus may be known by five remarkable
stars, 40 and 50 .apart, and 80 situa.ted as to form a regul~r
pentagon, or five-sided figure. Menkar, of the second
magnitude, in the nose of' the )fhaJa, is the largest star
in the group, or in the cooatellation.
,4' ORION lies south oC Taurus, and is one of the most
conspicuous and beautiful of the constellations.
The
'gure is that of a man in the act of assaulting the Bull,
with a sword in his belt, and a club in his right hand. It
contains two stars of the first magnitude, four of the
second, three of the third, and fifteen of the fourth. Be.
4epae forms the right, and Bellatriz the left slloulder.
A cluster of small stars forms the head. Three small'
stars, forming a straight lioe about 3 0 in length, constitute
the belt, called by Job" the BantU of Orion." They are
sometimes called the TAree Kifl6a, because they point out
the Hyades and Pleiades on the one hand, and Sirius on
the other. A row of very small stars runs down from
ihe belt, forming the BUJord. These, with the stars of
the belt, are sometimes called the Ell and Yard.
Mintika, the northernmost star in the belt, is less than
lOsouth of the equinoctial.
Rigel, a bright star of the first magnitude, is in the
left foot, 150 south of Bellatrix; and SaipA, of the third
magnitude, is situated in the right knee, st° east of
Cftt18
Rigel..
,
(TAe Hare) is direotly south of Orion. It may
be known by four stars of the third magnitude, in' the
form of an irregular square. Zeta, of the fourth magnitude, is the first star, situated in tbe back, and about
50 south oC Saiph ill Orion. A bout the same distance
below Zeta are the four principal stars, in the legs and
feet.
.
· QOL1JMlll (Noah'. Dime) lies about 160 south of Lp.pus
11 contains but four stars,. of which PAaet i~ the brig~t
• LBPUI
SOV~".!f
COBSI'BLUTION'.
171
eat. It lies on the right, a little higher than B8ItJ, the
next brightest. This last may be known by a amall star
just" east of it.
"
ERIDAInn]"
(The RiDe,. Po) is a large and irregular con-
stellation, very difficult to trace. It is 1300 in length,
and is divided iDto the NortJ&em and &u.them streams.
The former lies between Orion and Cetus, commenoing
near Rigel in the foot of Orion, and flowing out westerly
in a serpentine course, near 40°, to the Whale.·
lies southeast of Orion, and may be
readily found by the brilliancy of its priocipal star Siri~.
This is the largest of tne Fixed Stars, and is >supposed to
be the De~rest to the Solar"" System. .
"
CANIS MAJOR
is a small constellation situated between
Canis Major. and the Twills. It has but two principal
stars, namely, Procyon of the first magDitude, and Go..
melm of the second.
CA.NIS MINOR
MONOCEROS
(The Unicorn) lies between Canis Major
and Canis Minor, with its centre directly south of Procyon.
Its largest stars are of ~he fourth magnitude. Three of
these are in the head, 30 and 40 apart.
has its head near Procyon, and consists' of a
number of stars of ordinary brightness.. AlpAard, in the
heart, is a star of the" second magnitude, about 15° south.
east of the head. It "Is an extensive constellation, extend.
ing from east to weat more than 100° •.
HYDRA.
(The CrOfD) i. !represented as standing upon
the tail of Hydra, south of Coma Berenices. It contains
but nine visible stars, only three of which are as large as
the third magnitude.
"
CoRVUS
ARGO NAVIS
(The Ship Argo) is a large and splendid
constellation in tne southern hemisphere, but so low down
in the south that but little of it can be seen in the United
States. It lies southeast 0(. Canis Major, aod may b8
kDU"D by the stars in the prow of the ship.
Markell, of
the third Jnagnitude, is 16° "southealJt of Siriul. NOM .ad
\
180
D011BI&, UJ1tLB,
.um MVLTJPLB
ST.lBS.
~
are of the second magnitude, and Ct.opu and
_iapI,tJeitlu of the first.
CBXTAUBUS is another large southem constellation, too
low in the 80utb to be traced by an observer in the United
States.
Lvpus (The Woy) is next east of Centaurus, south of
Libra, and is also IDvisible in northern latitudes.
(The Seztaflt) consists or a number of very
lIIIall stars, situated between Leo on the north, and Hydr. 00 the south. Its largest star is of the fourth magnitude, and is situated about 18° south of Regulus, Dear the
eq uiooctial.
C.ux (The C1W8) is a brilliant little constellation, but
too Car south to be visible to us at the north. It coosists
of four prinoipal stars, namely, ODe of the firat, two of the
I8OODd, and one of the third magnitude.
•
SBXTANS
CHAPTER II.
or
DOUBLE, VARIABLE, AND TEMPORARY STABII.
BINARY SYSTEMS, &c.
Lesson
or DOUBLE,
1~4.
TRIPLB, AND K11LTIPLB STA...
(Map 16.)
1. MARY of the stars which, to the naked ~ye~ appear
lingle, are found, when examined by' the aid of a telescope,
to OOllsist of two or more 8tars, in a state of near proxjmity
to each other. Theee are called tltmble 8t4r.. When
three or more 8tare are found thus olosely connect. l , the,
. are called 'ripk or ",.ltiple stare. They are al80 iistio.
guiahed as 1IirJtzrr, ttmuJry, &c.
2 •. Double aDd triple stars are lupposed to be consti.
tuted in two ways: first, by actual ooDtiguity; and aN-
DOlJ'BLB, TRIPLE, AND XVLTIPLB STARS.
#
181
ondly, where they are only neB.r the same line. of vision,
one of the component stars being far beyond the Qther.
In the former case they are said to be physically double,
from the belief that they are bound together by attraction,
and that one revolves around the other, while in the latter
case they are considered as only uptically double.
Upon this subject Dr. Herschel remarks, that this near•
. ness of the stars to each other, in certain oases might ~
attributed to some accidental cause, ~id it oocur o~ly in a
taw instanoes; but ·the freq ueilcy of this comp'aniollship.,
the extreme closeness, and, in many oases,· the near
~qua1ity of the stars so oonjoined, would alone lead to a
strong suspicion of a more near and intimate relation than
mere casual juxtaposition.
·
~ 3. The figures from B to F on the map are speoimens
or double stars. B is a representation of the middle star,
Misar., in the tail-of the. Great Bear. It may be seen
double. with a good spyglass. The stars are both of a
greenish white-of the third and fourth magnitudes-and
about 141'/ apart. Mizar has sometimes been seen witTi.
out a companion, and· at other times it has been known
suddenly to appear. 'rhe companion is not .Alcor, near
Mizar, and ·visible to the naked eye, but a telescopic
814r.
C -is a view of the double star .Mintika, ~n the oonstel.
lation Orion. The component stars are of the first and
eighth magnitudes, the largest of a reddish hue, and the
small Qne white. They are about 10"1 apart, or ,four times
the diameter of the largest star.
·
D is Ii double star in Ur.,a Mincw, . commonly known
a8 the Pole 8tar. ft consists of a star of the second and
. an~ther of the ninth magnitude, situated about 181'/ apart;
or about four times the diameter of the larger star. They
are both of a silvery white.
It requires a pretty good telescope to show this sta r
dou~le, henoe it is considered a pretty good teat ob.
7pet, by observing which to ascertain the qualities of un
optical instrument, especially of the low-priced refrac.
tol"S.
'
E is a view of the double star Castor in the twius.
16
182
OF BINA.,y AND OTHBH. SYSTBJ(S.
The stars are of a greenish color, of the third and fourth
magnitudes, and about 5", or two diameters of the principal star, apart. This also is considered a good test object.
Through ordinary telescopes the stars seerD to be in contact, but with those
higher power they appear
r:ly
divided. These stars also constitute a binary system.
The stars under F are specimens of other distances and
combinations of magnitudes.
4. The number of double stars has been .variously esti.
mated. Sir William' Herschel enumerates upwards of
five hundred, the individuals of which are within 80"
each other. Profe880r Struve of Dorpat estimated th~
number at about three thousand, and more recent observations fix the number at not lees than six thousand.
The great number of the double Itars first led astronomers to suspect a physical connection by the laws of
gravitation, and also a reoolutiora of star around star, 88
the planets revolve around the IUD.
.
.
or
rai
or
Lessen
1~3.
OF BllfAJLY AKD OTUK SYSTBKS.
(Map 16.)
1. By carefully noting the relative distances and angular positions of double and multiple stars, for a aeries of
years, it has been found that many of them have their
ppriodic revolutions around each other. Where two stars
are found in a state of revolution about a common centre,
they constitute what is called a Binary SYBteff&. Thp.ae,
it must bf' remembered, are the double and multiple stars,
which appi'A.r single to the naked eye. Sir W. Herschel
noticed about fifty instances of changes in the angular
~sition of double stars, and the revolution of some 8i:I:tem
of these is considered certain. Their periods vary from
40 to 1200 years.
2. The star Xi, in the left bind paw of UrBa Major,
iR one of thp.se stellar systems. The revol ution of its
compon~nt stars' began to be noticed in 1781, siuc~
1
I
•
OF BINARY AND OTBBR SYSTBMS.
183
which time they have made one complete revolution,
and are now (1847) some eight y'ears OD the second.
Of oourse, then, their periodic time is about fiftyeight years. ~heir angular motion is about 60 24" per
year.
Dr. Dick supposes these stars to be some 200,000,000,000
miles apart; and upon the supposition that the smaller
revol ves around the latter, computes its velocity to be not
less than 2,471,000 miles every hour. This would be 85
times the veloci.ty of Jupiter, and 23 times the velocity at
Mercury-the swiftest planet in the Solar System.
3. :Fig. G on the map is a representation of another of
these binary systems. It consists of the double star
Gamma, in the Virgin. This star has been known as a
double stJlr for at least 130 years. l'he two stars ,re
both of the third magnitude, and of a yell<?wish color.
The largest star will be seen in the upper foci of the su pposed orbit, and the arrows show the direction of the re.
vol ving star. A t the first observation, by Bradley J in
1719, the smallest star was near the lower arrow t 8.
represented. In 1766 it occupied a very different position, as the drawing shows, and 80 on to 1844, as repre.
aented ~n the map.
The period assigned to this system by Dr. Herschel is
829 years. The late E. P. Mason, of Yale College, estimated its period at 171 years: more reoent observations
and estimates by Madler, give a period of 145 years.
4. Fig. H is a view of another of these systems of re.
volving 8ta~ namely, the double star p, or 70 of the Ser.
pent.bearer. In 1780 the smaller star was seen on the
right, just above the lower 'arrow. In 1804 it was near
that date on the map; in 1822, it was nearly opposite
the first position, and 80 on to 1843.
The periodic time of' the revolving star is about 93
years. In the course of its revolution the two stara
8Om~times appear separated, sometimes very near to.
gether, and at other times as one star. They are of, the
5th and 6th magllitudes, and of a yellowish hue.
The following table shows the periodic times, &c.,
~ese Binary Systems, 80 Car as known. It is copied from
or
184
or B",.£aT AND OTBBJI. SYSTDI.
Hersohel'. Treatiae, and corrected where more reoem
obaenatiooa have shown it to be erroneous.
NUDeI.
i
Penod in
year..
J
I
CoronE,
43.40
55.00
Caneri,
58.26
U ram Majoris,
93.00
70 Ophiuchi,
452.00
61 Cygni,
252.66
r Virginilll,
286.00
Castor,
145.00
d CoronE,
1200.00
r Leonia,
'I
I
lIajor axil of i
..
J
t~e orbit.
Eecentnclt,..
I
7N.714
8.784
24.000
16.172
7.358
30.860
0.4164
0.4667
0.8335
0.7"582
0.6112
I
I
5. The atudeDt should here be reminded that these are
oot .Yltema of plaoef.l revolving around suns, but of ...
refHJZfli"K tlrou'ltll ft.; and that their component stars
may not only be as far apart as our SUD and Sirius, but
that they are probably each the ceotre of his own planetary system, like that which revolves around our eentral
orb. Speaking of these .Y8tems. Dr. Dick observes:
" To some minds, Bot accustomed to deep reflectioo, it
may appear a 'Yery trivial fact to behold a small and
scarcely distinguishable point of light immediately adjacent to a larger star, and to be informed that this lucid
point revolves around its larger attendant; but this phenomenon, minute and trivial as it may at first sight appear, proclaims the astonishing fact, that SUNS REVOLVB
AROUND SUNS, AND SYSTEMS ABOUND SYSTEMS.
This is a
comparatively new idea, derived from our late sidereal
investigatioos, and forma one of the most sublime conceptions which the modem discoveries of astronomy have
imparted. It undoubtedly conveys a very sublime idea,
to contemplate such a globe as the planet J upiter-a
body thirteen hundred times larger than theearth-revolving a round [he 8un, at the rate of twenty.nine thouIUld mile. every hour; and the planet Saturn, with i.
OF BINARY AND OTHER SYSTEMS.
185
rings and D1OODS, revolving in a similar mat:ner round
this central orb in an orbit five thousand six hundred
and ninety millions of miles in oircumference. But how
much more august a.nd overpowering the conception of a
aun revolving around another sun--of a sun encircled
with a retinue of huge planetary bodies, all in rapid m0tion, revolviDg round a distant sun, over a oircumference
a hundred times larger than what has been now stated,
and ~ith a velocity perhaps a hundred times greater than
_that of either Jupiter or Saturn, and oarrying all its
planets, satell ites, comets, or other globes along with it in
its swift career! Such a SUD, too, may as far exceed
these planets in size as our 8un transcends in magnitude
either this earth or the planet Venus, the bulk of anyone
of whioh scaroely amounts to the thirteen .. hundred.thou.
sandth part of the solar orb which enlightens our day.
The further W~ advanoe in our explorations of the distant
regions of space, and the more minute and specific our
investigations are, the more august and astonishing are
the scenes which open to our view, and the more elevated
do ·our conceptions become of the grandeur of that AI.
Inighty Being who' Dlarshalled all the starry hosts,' and
of the multiplicity and variety of arrangements he has introduced into his vast creation. And this consideration
~ught to serve as an argument to· every rational being,'
both in Ii scientific and a religious point of view, to stirn.
ulate him to a study of the operations of the Most High,
who is 'wonderful in couDsel ~nd excellent in working,'
and whose works in every part ClC his dominions adum.
brate the glory of his perfections, and proclaim the depths
of his wisdom and the greatness of his power."
6. Ilesides the revolutions of these double stars around
each other, they are found to have a proper motion together in space, like that which our sun has around the
great Central Sun. Upon this subject Sir John Herschel
observes, that these stars not only revolve around each
other, or about their common centr~ of gravityJ but that
they are also transferred, without parting company, by a
progressive motion common to bo~h, towards some deter-
minate region.
1
186
OF BDlny .&IfD O'tUB SYSTEIIS.
" For example, tbe two staIB or 61 Cygni, which .,.
nearly equal, have remained constantly at the same, or
very Dearly the same distance, or 15", Cor at least fifty
yean put. Meanwhile they have shifted their local sit.
uation in the heayenB, in this interyal of time, through DO
lese than 41 23", the annual proper motion or each star
being 6'/.3; by which quantity (exceediDg a third of
their inlenal) this system is every year carried bodily
along iD BOrne unknown path, by a motion which, for
many centuries, must be regarded as unifonn and recti.
linear. Among stars not double, and DO way differing
(rom tbe rest in anyotheE obvious· particular, ,. Cassiapeim is to be remarked as having the greatest proper wo.
tion of any yet ascertaioed, amounting to 3".74 of annual
displacement. And a great many others have been observed to be thus constantly carried away from their
places by smaller, but Dot less unequivocal motions.
" Motions which require whole centuries to accumulate
before they prod uce changes of arrangement, such as the
naked eye can detect, though quite sufficient to destroy
that idea of mathematical fixity which precludes specula.
tion, are yet too trifling, 88 far as pra.ctica~ applications
go, to induce a change of language, and lead us to speak
of the stars in common parlance as otherwise than fixed.
Too little is yet known of their amount and directioDs, to
allow of any attempt at referring them to definite la WI.
lt may, however, be stated generally, that their apparent
directions are various, and seem to have no marked com.
mon tendency to one point more than to another of the
heavens. It was, indeed, supposed by Sir William Her.
achel, that such a oommon tendency could be made out;
and that, allowing for individual deviation8, a general receS8 could be perceived in the principal stars, jrOJll. that
point ocoupied by the star { Herculis, I!nDaTtU a point
diametrically opposite. This general tendency was re.
ferred by him to a motion of the sun and solar system in
the opposite direction. No ODe, who reflects with due at.
tention on the subject, will be inclined to deny the high
probability, Day, certainty, that the SUD htu a proper mo.
tion in 80me direction; and the inevitable oonseq uence of
.1
.
~
187
O' B1!4AB.Y A.N.1) OTHER SYSTEMS.
8uch a motion, un participated by the rest, must be a slow
tlOBra,ge apparent tendency of all the stars to the vanish.
iog point of lines parallel to that direction, and to the region which he is leaving."·
..
7. As already stated in a previoU8 188800, m,any of the
double, triple, and multiple stars are of "ariofU COM',
beautifully contrasting with each other.
fC _ _ _ _.
other SUDS, perhaps,
:With their attendant moons
,
Communicating male and female light,
(Which two great sexes animate the world,)
Stored in each orb, pt'rhapa, with lOme that live."t
"In such instances, the larger star is usually of a ruddy
or orange bue, while the smaller one appears blue or
green, probably in virtue of that general law of optics,
which provides that wben the retina is under the influ.
ence of excitement by any bright-colored lights, feebler
lights, which seen alone w.ould produce no sensation but
of whitf'ness, shaU.J9T the time appear colored with the
_tint complementary 'to that of the brighter. Thus, a yel.. low color predominating in the' light of the brighter star,
that of the less bright one in the same field of view will
appear blue; while, if the, tint of the brighter star verge
to crimson, that of the other will exhibit 8 tend~ncy to
green--or even appear as a vivid green, under favorable
circumstances. The former contrast is beautifully ex.
hibited by. Cancri-the'latter by r Andromedm; both
fine double stara. If, however, the colored star be
much the less bright of the two, it will not materially
affect the other. Thus, for instance, 'J Ca~iopeim exhibits the beautiful combination of a large white star, and
a small one of a rich ruddy purple. It i$ by no means,
however, intended to say, that in all such cases one of the
colors is a' mere effect ~f contrast, and it may be easier
luggested in words than conceived in imagination, what
variety of illumination t'IDO BUnS-a red and a green, or a
t
<.
.-------------------------------------------• Sir Johu Henchel'. Treati8e OD AaboDOlDJ.
t Paradile Lo.i, 'YiiL, 148.
•
'.
188
v A&UBLB
0& PB&IODICAL STA )l.S.
yellow and a blue one--must aff'oN a planet
cir~ulating
about either; and what charming contrasts and 'grateful
vicissitudes'-a red and a green day, for instance, alternating with a white one and with 4arkness-might arise
from" the presence or absence of one or oth~r, or both,
above the horizon. Insulated stars of a red color, almost
u deep as that of blood, ocour in many parts of the beav.,
eDS, but no green or blue star (of any decided hue) has,·
we believe, ever been noticed un associated with a com.
panion brighter than itself."*
Lesson
1~6.
V ARIABLB 0)1. PB)l.IODICAL STAlLS.
1. Variable stars are those which undergo a regular
periodical increase and diminution or lustre, am.ouoting,
ID some cases, to a complete extinction and revival.
These variations of brilliancy, to which some of the
fixed stars are subject, are reckoned among the m081
remarkable of the celestial phenomena. Some oC .them
pass through their successive changes with great rapidity, while in other cases their brilliancy is increased or
diminished gradually for months. The time" occupied by
one of these stars, in passillg through all their different
phases, is called its period.
2. One of the most remarkable or these variable stars,
is the star Omicron, or Mira in the Whale. I ts period is
about 332 days, during which time it varies from a star
the second magnitude, to complete invisibility. It
appears about twel va times in eleven years-remains at
its greatest brightness about a fortnight, being then, 00
lOme occasions, eq ual to a large star of the second magnitude. It then decreases for about three months, wheo
it disappears. In about five months it becomes visible
again, and continues to increase during the remaining
three months of its period.
Its increaSe of light is much more rapid than ita
or
• Sir John HellChel'. Tleame -
A.a.om,.
VAIUABLB OR PBa:ODICAL IT.lBS.
189
decrease. It increases from the sixth to the second
magnitude in 40 days-continues thus brillia.nt jl6 days,
and then fades to the sixth magnitude again in 66 days.
Hence, it is above the sixth magnitude for 182 days, and
below 200 days of its pe'riod.
3. Another remarkable periodic star is that called
Algol, in the constellation Per8eua. It is usually visible
as a star of the second magnitude, and such it continues
for the space of 2 days 14 hours~ when it suddenly begina
to diminish in splendor, and in about 3! hours it is red uced to the fourth magnitude. It then begins again to
increase, and in 3l hours lDore is restored to its usual
brightness, going through all its changes in 2 days 20
hou rs and 48 minutes, or thereabouts. Through all its
successive changes, this star shines with a white light,
while the color of all the other variable stars is red.
4. The cafUB of these' periodic variations in the brightness of soml\ .)f the stars is not known. Some suppose
them to be occasioned by opaque bodies revolving aroul'd
them, and cutting off a portion of their light from u ••
,Speaking of the sudden obscuration of Algol, mentioned
above, Dr. Herschel remarks, that it indicates a high degree
of' activity in regions where, but for such evidences, we
might conclude all lifeless. " I am disposed," says Dr.
Dick, "to consider it as highly probable, that the· in.
terposition of the opaque bodies of large planets revolving
around stich stars, may, in some cases, account for the
phenomena. It is true, that the planets connected with
the Solar System are 80 small, in comparison of the SUD,
that their interposition between that orb and a spectatf?r
at an immense distance, would produce DO sensible effect. But we have no reason to conclude, that in all
other systems the planets are formed in the same proportions to their central orbs as ours; but, from the
variety we perceive in every part of nature, both in
heaven and earth, we have reason to conclude that every
system of the universe is, in some respects, different
from another. There is no improbability in admitting,
that the planets which revolve round some of the stars,
may be so large as to lK"" a coDsiderable proportipn
190
V..a'A BLa
oa PUIODICAL ITAal.
(perhaps one.half or one-third) to the dfametera of the
orbs around which they revolve; in which case, if tbe
plane of their orbit lay nearly in a line of our own
vi8ion, they would, in certain parts of thQir revoluti~ns,
interpose between our eye and the stars, so as to hide
for a time a portion of their surfaces from our view
while in that part of their orbits which is next to the
earth. "
With reference to the obscuration and period of Algol,
Professor Olmsted observes, that the periodic time of an
ovaque revolving body, 8uffi'Ciently large, which would
produce a similar temporary obscuration of the 8un, seen
from a fixed atar, would be less than fourteen hours.
Others again are of opinion that those distant suns
have one luminous and one dark or clouded hemisphere,
and that their variations may thus .. result from a revolution upon their axes, by which "they would present us
alternately with their full and their diminished lustre.
A nother theory is, that these stars are moving with
inconoeivable velocity in an immensely elliptical orbit,
the longer axis of which is nearly in a direction to the
eye; and the shorter axis of which would be imperceptible from our system. In such case the star would appear
alternately to approach and recede, now looking in upon
our quarter of the universe, as it were, for a few days,
and then rushing back into immensity, to be seen no more
by human eyes during the lapse of years or of ages.
" Whatever may be the causs," says Mr. Abbott, "the
fact of these variations is perfectly established, and the
contemplation of the stupendous changes which must be
occurring in those distant orbs, overwhelms the mind with
amazement. Worlds vastly 18 rger than our sun sudden.
ly appear, and as suddenly disappear-now they blaze
forth with most resplendent brilliancy, and again they
fade a \vay-and .often are apparently blotted from
existence. These worlds are unquestionably thronged
with myriads of inhabitants; and the phenomenon which
to us appears but as the waxing or waning lustre of a
twinkling star, may, to the dwellers on these orbs, be
evolutions of grandeur, sucb as DO earthly imagination
.
--
TBJlPOBAKY ITAB,S.
191
bas ever conceived. But these scenes, DOW Teilecl from
human eyes, will doubtle. all be revealed, when the
Christian shall ascend on an angel's wing to the aDgel'.
home."
Lesson 1117•
TEMPOllA.llY STABS.
1. Temporary stars are those which have appeared
- from time to time, in different parts of the heavens, blazing forth with extraordinary lustre, and after remaining
tor a while apparently immoveable, died away, and left
no traces of their existence behind. Some writers cl_
them among the Periodical Stars, while others notice them
under the head of " New and Lost Stars."
"
2. A star of this kind, which appeared in the ye.ar
125 B.
led Hipparchus to draw up a catalogue of the
IItarl, tbe earliest on record. In A. D. S89, a similar star
appeared Dear the largest star in the Eagle, which, after
temaining for three weeks 88 bright as Venus, disappeared entire} y from view.
3. On the 11th of November, 1572, Tycho Brahe, a
oelebrated Danish astronomer, was retu~ning in the eveDing from bi. laboratory to hie dwelling~house, when he
was surprised to find a group of couotry-people gazing
upon a star which be was sure did not exist half an hour
before. It wal then as bright as Sirius, and continued
to increase till it surpa.ed Jupiter in brightness, and
was visible at noonday. In December of the same year
:it began to dimillish, aDd in March, 1574, had entirely
diaappeared.
This remarkable star was in the constellation Ca88i.o.
IMia, about 60 northeast of. the star Cap". The pluce
where it once shone is now a dark void!
This star was observed . for about sixteen lllootbs, and
.during the time of its visibility its· color exhibited all the
dift'erent shades of a prodigious fiame-" first it was of a
dazzling white, then of a reddish yellow, and lastly of an
ashy paleness, in whioh ita light expired." "It is im.
c.,
-------
192
TDPPIl.A.llY STARS.
possible," says Mrs. Sumerville, "to imagine any tbi.
more tremendous than a conflagration that could be visible at such a distance."
In reference· to the same phenomenon, Dr. Dick 01>-I8nes, that" the splendor concentrated in that point
the heavens where the star appeared, must have been, in
reality, more thaD equal to the blaze of twelve hundred
thousand worlds such as ours, were they all colleoted
into one mass, and all at once wrapped in flames. Nay,
it is Dot improbable, that were a globe as large as would
ill the whole circumference of the earth's annual orbit,
to be lighted up with a splendor similar to that of the
8un, it would scarcely surpass in brilliancy and splendor
the star to which we refer."
The same writer observes, that" within the last ceolury, no le~ than thirteNJ stars in different constellatioll8
.aem to have totally perished, and ten new ones to have
been oreated."
REV. PROFESSOR VINCE, who
been characterized lUI
"one 'of the most learned and pious astronomers of the
age," advances the opinion that "the di~appearance (-f
lOme stars may be the destruction of that system at the
time appointed by the
for the probation of its illhabitants; and tbe appe~rance of new stars may be the!
formation of Dew systems for new races of beings than
called into exiltence to adom the works of their Crea-
or
haa
n,rrY
tQr."
L.A.. PLA.CE,
whose opinion upon such subjects is always
entitled to consideration, says: "As to these stars which
luddenly shine forth with a very vivid light, and then im- .
mediately disappear, it is extremely probable that great
conflagrations, produced by extraordinary causes, take
place on their surface. This conjeoture is confirmed by
their change of oolor, which is analogous to that presented to us on the earth by those bodies which are set OD
fire and then gradually extinguished."
DR. GOODB, author of the Book of Nature, &0., seelDfl
to have entertained an opin~on similar to those already
expressed. "Worlds and systems of worlds," says he,
"are Dot only perpetually 9reating, but al80 perpetual},
,
-..,
PALLING OR SBOQTING nABS.
193
disappearing. It is an extraordinary fact, that within the
period of the last century, not less than tAimen ,tar., in
different constellations, seem to have totally perished, and
~ fle1D onea to have been oreated. In many instances it
is unquestionable, that the stars themselves, the supposed
habitations of other kinds or orders of intelligent beings,
.together with the different planets by which it is probable they were surrounded, ha va utterly vanished; and
the spots they ocoupied in the !teavens have become
blanks. What has befallen other systems, will assuredly
befall our own. Of the titTLe and manner we know noth.
ing, but the fact is incontrovertible; it is foretold by revelation; it is inscribe{f in the heavens; it is felt Ithrough
the earth; such is the awful and daily text. What then
ought to be the comment 1"
~
Lesson 1118.
I
• J
I
PALLING OR SHOOTING STARS.
The subject of shooting stars is here introduced, not
because it properly belongs here, by the laws of philosophical classification, but because the juvenile student will be
more apt to look for it in this connection than in any other
part ot the work. We must say but little, however,
as its full discussion falls not within the compus of our
design.
.
1. Falling or shooting stars are not properly 614r., of
any kind, but meteor., witllin a sbort distance or the earth.
A meteor is a fiery or luminous body fiying through the
atmosphere.
2. Although the number of shooting stars observable
in a single night is usually small, there have been instances in which they feU in suoh numbers as to be de.
nominated Meteoric 8lwwr,. One
these occurred
November 13th, 1838. On that morning, says Professor
Olmsted, from two o'clock until broad daylight, the sky
being perfectly serene and cloudless, the "hole heavens
were lighted with a magnificent display of celestial fire.
works. .At time. the air was filled with streaks of light.
or
17
·
194
.-
OF CLUSTBB.S OF STA.KS.
occasioned by fiery particles darting down 80 swiftly as
to leave the impre~ion of their light on the eye, (like a
match ignited and whirled before the face,) and drifting
to the northwest like flakes of snow driven by the WiDd ;
while, at short intervals,· balls of fire, varying in size
from minute points to bodies larger than Jupiter and Vonus, and in a few instances as large as" a full moon,
descended more slowly along the arch of the sky, often
leaving after them long trains of light, which were, in
801ne instances, Tariegated with different prismatic colors.·
3. Of the nature of these meteors very little is known.
They are supposed to descend from some point beyond
the limits of our atmosphere, and to be ignited by their
rapid motion, as they come in contact with it. They explode, and are reerolved into srnaH clouds, it is thought, at
the height of about thirty miles above the earth.
Professor Olmsted thinks they are caused by some rare
body like the tail of a comet, or the zodiacal light, falling
in the way of the earth in her annual joumey around the
8UD.
CHAPTER III.
OF CLUSTERS OF STA.RS, A.ND NEBUL£
Lesson
1~9•.
01' CLUSTERS OF STA.RS.
(Map 16.)
1. IN Iu"eying the concave of the h~veD8 in a
clear night, we observe bere and there groups Qf stars,
forming bright patches, as it d ra WD together by' tlOme
cause other tha.n casual distribution. Such are t'he
Plri4du and By. in Taurus, the fOrmer of which
• Introduction to Astronomy, p. ~
-
1
01' CLt18TBB.S OF STARS.
196
may be aeen at I, on the map. These are called OZUW8
of Star.. 'The constellation Coma Berenice, is another
such group, more diffused, and consisting of much larger
stars. The luminous spot called the Bee Hi'Oe, in Can.
oer, is somewhat similar, but less definite, and requires a
moderate telescope to resolve it into stars. In the sword.
handle of Perseus, is another such spot or cluster, which
req uires a rather better telescope to reSQI ve it into distinct
stars.
2. There is a great number of these objects, which
have been mistaken for comets, as through telescopes
moderate power they appear like the comet of 1585, Map
15, or like small round, or oval, nebulous specks. Sir
John Herschel observes that Messier has given a litit of
103 objects of this sort, with which all who search for
comets ought to be familiar, to a void being misled by
their similarity of appearance. That they are not comets, however, is evident from their fixedness in the heavens, and from the fact that when we come to examine
them with instruments of great power, they are perceived
to cODsist entirely of stars, crowded together so as to occupy almost a definite outline, and to run up to a blaze
of light in the centre, where their condensation is usually
the greatest.
3. Many of these olusters are of an exactly round
figure, and, convey tbe complete idea
a globular space
filled full of stars, insulated in the heavens, and constituting in itself a family or society apart from the rest, and
lubject ooly to its own intemallaws.
4. It would be a vain effort to attempt to oount the
. stars in one of these globular cluste ..s. They are not to
be reckoned by hundreds; and on a rough calculation,
grounded on the apparent intervals between them at the
borders, and the angular diameter
the whole group, it
would appear ~hat many clusters of this description must
contaio" at least from ten to tweoty thousand stars, com.
pacted ,and wed2ed together in a round space, whose an.
gular diameter does not exceed eight or ten minutes, or
an area equal to a tenth part
that covered by the·
or
or
or
or
mooD.
196
OP NBBVU.
5. Some of these clusters are of an irregular figure, as
may be seen at J, on the map. These are generally less
rich in stars, and especially less condensed towards the
centre. They are also less definite in point of outline.
In some of them the stars are nearly all of a size, in oth.
ers, extremely different. It is no unCODlmon thing to find
a very red star, much brighter than the rest, occupying a
conspicuous situation in them.
6. It is by no means improbable that the individual
lltars of these clusters are suns like our owo, the centres
of 80 many distinct systems; and that their mutual distances are equal to those which separate our 8un from
the nearest fixed stars. Besides, the round figure of
lOme of these groups seems to indicate the existence
lOme general bond of union in the nature of an attractive
(orce.*
7. Figure J on the map, is a representation of the cluster in Coma Berenices already referred to; and Figure K
is a magnificent cluster in Capricornus, containing more
than a thousand fixed stars.
A cluster of stars, numbering over 1,000, bas recently
been. announced as discovered by Professor Mitchel, of
the Cincinnati Observatory.
or
Lesson 130.
OF NEBULAS •.
(Map 16.)
1. The term NEBt1L.E is 8.pplied to those clusters
ata~ that are so distant as to appear only like a faint .
cloud or haze of light. In this sense some of the clusters
heretofore described may be classed as nebulre, and in.
deed it may be said of all the various kinds of nebul."
that it is impossible to say where one s~cies ends and
another begins.
2. RBSOLVABLE NEBUL.& are those clusters the light
of whose individual stars is blended together, when seeD
or
,
• Bench.I'. Treat. .
II
197
through a common telescope, but which, when viewed
through glasses of sufficient .power, can be resal ved into
distinct stars.
S. lUBSOLVABLB NBBUL& are those nebulous spots
which were formerly supposed to consist of vast field. of
matter in a high state of rarefication, and not of distinct
.-tars. But it is exceedingly doubtful whether any nebu..
1., exist which could not be resolved iDto stars, had we
telescopes of sufficient power. The following remarks,
taken· from a lecture recently delivered in Dublin, by
Dr. Scoresby, in relation to the powers of Lord RoSIe's
mammoth telescope, will reflect light upon the subject un.
der consideration. "A bout the close of last year, the
Earl of Rosse succeeded in getting his great telescope
into oomplete operation, and during the first month of his
obeervations 00 fifty' of the unresolvable nebulm, he 8Uooeeded in asoertaining that forty-three of ~hem were already resolvable int6 masses of stars. Thus is confirmed
the opinion, that we h~ve only to increase the powers of
the instrument to resolve all the nebulm into stars, and
the grand nebular hypothesis of La Place into a splendid .
astronomical dream."
In a more recent communication Dr. Scoresby remarks,
that the nebulre already observed were belween one and
two hundred, which was doing well considering the ob.
aervatioDs had often been obstructed by the cloudy nights.
Although this great telescope has been erected nearly'
two years, it has not been in complete operation more
than six or seven months, and already the nebulm, not be. fore fully examined, have been discovered to be a collection of SUDS.
From these recent observatioDs it is probable that all
the nebulm might be resolved into distinot stars if we had
telescopes of suiicient power, and that such an objeot u
an irresolvable nebula does not in reality exist.
While upon the subject of the nebulre, as viewed by
Lord Rosse, we must not omit to notice the extraordinAry
spiral nebula, recently discovered by the aid of his mam.
moth telescope. The following is the announcement
the dilCOvery, u given in the English journala:
or
17*
198 .
UTIlAOIlDINA.IlY
OP NEBULa.
SPIB.A.L
NEBULA.
DISCOVBRBD
BY
LOU
B.OSSB.
The Spiral Nebula is situated in the Dog's Ear, and
although, by the oommon consent of astronomers, it was
considered a mighty 01 uster of stars, it was not until ~rd
Roese had seen it by the aid of his six-feet mirror that iii
resolution into stara was effected. This wonderful nebula
bears closely on a problem relating tQ the structure of
our own galuy, the Milky Way. However strong the
aympathies pe"ading all that strange system, it is cognizable by U8, in the mean time, only as a collection of
leparate masses. N or can we err in so deeming it,
through ignoranoe of its real, as compared with its apparent structure, inasmuch as it is the manifest tendency.,
of the telescope to deprive these remote objects of apparent uniformity, and endow them with a constitutioD
more and more discreet. Now, these parts are, by themselves, somewhat intelligible. The central spherical
group has the form in which gravity would sustain any
mass of stars; and most of the other segregated ponioDl
also can be ~onceived as partial schemes internally har.
monious, or arranged in obedience to their internal sym.
pathies. But the feature the most remarkable for U8 is
the character of the two principal lines of the scroll, or
those two leading 'branches of that Milky Way where the
stars of the group appear mainly distributed. It seems
as if these beds of orbs we ra lite rail y di8801 ving into fragments, which, in fact, is only a repetition of the moet
conspicuous characteristic of the zone enoircling our own
.galaxy; for the bright circuit of our Milky Way is DO
regular belt, but,. on the contrary, a suocession of olu8teN, probably self-harmonious, stretching along its whole
course, and separated by lines or patohes more or less
obscure.
Nothing oan be more memorable than the coDversion
of these dim streaks of light into burning and rolling
orbs: even a feat 80 grand and triumphant, in regard
the science and art of man, has an attraotion infinitely
less than the tranaforming of a shape apparently simple,
or
01' NBBtJL.&.
199
Into ODe 80 strange and complex that there is nothing to
which we can liken it, save a scroll gradually uDwinding,
or the evolutions of a gigantic shell! How passing mar.
venous is this universe! And unquestionably that form
would seem stranger still, if, rising farther above the imperfections of human knowledge, we couhlP see it as it
really is; if, plunging into its bosom and penetrating to
its farther boundaries, we could develop the struoture ot
its still obscure nebulosities, which doubtle. are Itreamll
aod masses of gorgeous related stars!
• .
Figure L on the map is a representation of the great
Debula in Andromeda, fonnerly considered as irre8Olvable. It resembles a comet, and may be seen under
fav~rable circumstances by the naked eye, like a small
faint cloud. The stars leen within its limits are supposed to be beyond it, and consequently seen through it.
4. N ebulm are again distinguished as Single and
DOUBLB N BBtTL.&. The former consist of one cl ulter
aantling alone, while in the latter case two or more seem
to be united, or in a state of near proximity, as in
Figure M. Of the Double Nebulae there is almost every
possible variety of form and proportionate magnitude.
The specimen given is a representation of the double
nebulm in the Greyhound.
5. Figure N is a representation of what are called
HOLLOW NBBULJI. This speoimen may be found in the
constellation Sagittariul.
6. STELLAR NBBVL..., or Ne1nilotu Star" are Iuch u
present the 'appearance of a thin clolld with a bright
star in or Dear the oentre. They are round or oval.
shaped, and look like a star with a burr around it, or a
candle shining through hom. Figures 0 and P on the
map are specimens of this class. 0 is in Cancer, and P .
in Gemini.
.
7. The SUA is considered by astronomers u belonging
to this class of nebulous stars, and the ZodilJClJl Light, 'of
which we have spoken in Lesson 108, has been regarded
88 of the nature of the gaseous matter with which the
Debulous stars are surrounded. It is supposed thAt if we
were as far from the SUD as we are from the Stella,
toe
OP NmI11L.&.
Nebul., he would appear to
UI
only u a smalL aDd
nebulous star !
8. PLANBTAB.Y NuvL.&, 8ays Dr. H"erschel, are Tety
Btraordioary objects. They have, as their name imports, exactly the appearance of planets; round or
.lightl y oTal discs, in some instances quite sharply terminated, in others a little hazy at the borders, and of a
light exactly equable or only a very little mottled, whioh,
in some of them, approaches in vi vidne8S to that of the
actual planets. Whatever be their nature, they must
be of enormous magnitude. Granting these objects to be
equally distant from us with the stars, their real dimeDlions must be such as would fill, on the lowest computa.
tion, the whole orbit of Henchel.
Fig. Q on the map,- is in&ended as a specimen or
Planetary N abulm, though, it must be confessed, it is not
easy to get up a very striking resemblance.
9. ANNULA.B NBBUL.& alao exist, but are seldom to be
met with. The most conspicuous of this class is to be
found exactly half. way between Beta and &4"","" in the
Lyre, and may be seen with a telescope of moderate
power. It is small, and particularly wall defined, 80 88
ID fact to have much more the appearance of a flat oval
aolid ring than of a nebula. The space within the ring
Is filled with a faint hazy light, uniformly ~pread over it,
like a fine gauze stretched over a hoop.10. Figure R is a representation of a very remark.
able nebula in the head of the Greyhound, about six
degrees below Mizar, the middle star in the tail of the
Great Bear. I t consists of a large and bright globular
nebula 8urrouDd~d by a double ring, at a considerable
distance from the globe, or rather a single riQg divided
through about two-fifths of its oircumference, and having
one portion turned up, as it were, out of the plane of the
rest. A faint nebulou8 atmosphere, and a small round
nebula near\it, like a satellite, completes the figure.
11. Figure S is another remarkable nebula in the
OODstellatioD or the Fox. The two round spots about tile
. • Sir J.
BencheL
OJ' NBBVL.&.
201
foci of the ellipee or oval, exhibit b~t a (aint and dusky
light, while the portioDS about the ends of the sborter
axis are remarkably bright and uniform.
12. Figure T represents a wonderful nebula in the
Milky Way. Its form is fantastic, and it has several
openings, through which, as through a window, we seem
to get a glimpse of other heavens, and brighter regiona
beyond ..
13. The "uIIINr of nebulo1;1s· bodies is unknown, per.
haps we' should say innumerable. They are especially
abundant in the Galiuyor Milky Way. Sir W. Her.
ache) arranged a catalogue showing the places of ,.,
Uatnuand of these objects. They are of all shapes and
sizes, and of all degrees of brig~tnes8, from .the faintest
milky appearallce to the light of a fixed star.
14. Star Dust is a name given to those exceedingly
faint nebulous patohes that appear to be scattered about
at random in the far.distant heavens. They have DO
definite boundary, and are well represented by the grfJg
portions of the map, between the various speoimens of
nebulm. The map is printed light or gray on purpose to
furnish specimens of Star Dust, or of nebulm 80 remote
as to be barely visible through the best telescope.. This
olass of nebulous appearanoes seems to lie in the back.
ground, far beyond others that are more distinctly visibl~
By placing the learner at a proper distance (rom the
map, the idea we wish to convey will be readily under..
,
• 000.
to.
This map may be used to very good advantage
to illustrate the uses and powers of the. telescope, in re.
IIOlving oebullB into stars. Place the pupil at the distance of from fifteen to twenty feet, according to the
strength of the light, so that he will see the clusters J and
K only as faint oloudy patches. Let him then make
what he may call a telescope of low power, by rolling
up a sheet of paper, and looking through the tube thul
formed., Shutting the surrounding light from his eye
will enable him to see the nebulous spots far more dis.
tinctly. 'fhen, instead of a telescope of higber power,
let hbn approach balf way to the map, and look agaill .
•
•
202
OF . . . . . . .
through his paper tube. IC the light is good, J and It
will be moaIy reaolved into atara. By approaching still
Dearer, more stars will be I8eD wbere it appeared nebu10118 befbre, and at leogth the &.r Dut will be seeD
11iD8 beyood the more djstinct nebube, in remote regiODII
or_pace.
It muat not be supposed, however, tbat barely shutting
the surrounding light (rom the eye is the principle upon
which the teleaoope reveals objects othenriae invisible;
the object in these ezerciseB is merely to show that 88 the
nearer we are to an object the more distinct the vision,
10 the beuer the telescope (an instrument which seems to
bring objeota towards us) the more perfect the view we
have of the durareDt kinds of nebulae, and the more likely
they are to be reeolved into distinct stars.
16. The nebulm, says Sir John Herschel, furnish in
every point of view an inexhaustible field oC speculation
ad conjecture. That by Car a larger share of them COD·
m.t of stars, there can be little doubt; and in the inter.
minable range of system upon system, and firmament
upon firmament, which we 1hua catch a glimpse of, the
imagination is bewildered and lost.
, 17. The Milky Way is generally regarded byastrono.
men u only a specimen of nebulm, of which our sun is
ODe of the &tall. This zone of Hlnall stars (for such it
actually is) extends quite around the Solar System, as the
Debulqus circle oC Figure R, on the map, extends around
the large Itar in the centre. Like that circle, also, the
Milky Way is divided through. some part of its circuit,
and bu various branches and irregularities.
The vast apparent ~t of the Galaxy, as compared
with other nehulm,_ is supposed to be justly attributable
to its comparative
Were we al rar from the
Solar System as we ~re from the nebula in the Lyre,
Fig. R, the Milky W~y would doubtless appear as aD
Annular Nebula no larger than that. It may therefore
with pro~riety be called "the Great Nebula of the Solar
System.'
The general ooDclusioDI of Midler respeoting the COD.
ltitution of the whole Iystem Qf the hed stars, Roluaivi
I
taearrle,..
•
OF NEBUL.E.
203
,
distant nebulm, are the following :-He believes
that the middle is indicated by a very rich group, (the
or the
Pleiades,) containing many considerable individual bodies,
~ough at immense distanoes (rom U8. Round this he
supposes that there is a zone, proportionally poor in stars,
and then a broad, rich, ring-formed layer, followed by an
• "'lerval comparatively devoid of stars, and afterwards by
another annular and starry space, perhaps with several
alternations of the same kind, the, two outmost rings com.
posing the two parts of the Milky Way, which are COD·
founded with each other by perspective in the portions
most dis~ant from ourselves.
But what an idea is here conveyed to the mind of the
almost boundless extent of the Universe! Sir W. Her.
schel estimated that 50,000 stars passed the field of his
telesoope, in the Milky Way, in a single hour! And yet
the space thus examined was hardly a point in this great
zone of the "sun-strown firmament." The mutual distances of these innumerable orbs are probably not le88
than the distance from our sun to the nearest fixed stars,
while they are each the centre of a distinct system
worlds, to which they dispense light and heat.
Were the Universe limited to the Great Solar Nebula,
it would be impossible to conceive of its almost infinite
dimensions; but when we reflect that this vast and glowing zone of suns is but one of thousands of such assem.
blages, which, from their remoteness, appear only as
fleecy clouds hovering over the frontiers of space, we are
absolutely overwhehned and lost in the mighty aby~ of
being!
And here we may leave the reader to his own reflec.
tions. While unnumbered worlds and systems of worlds
glow before his vision in the distant heavens, peoplin,z, as
it were, every portion of the mighty void, let it not be for.
gotten that as productions of the great Architect" these
are but parts of his ways." While he upholds them aU
"by the word of his power," and presides over them 88
the GREAT KING, the falling sparrow attracts his notice,
and the very hairs of our heads, are numbered. And·
while we behold his Wisdom, Power, and Goodness If)
or
204
OF KBIJUL.&.
gloriously inscribed in the heavens, let us learn to be
humble and obedient, to love and serve our Maker here,
that we may be prepared for the more extended scenes
oC another life, and for the aociety of the wise and -goQd
in a world to eome.
.
~
APPENDIX.
Aberration, an apparent
ch~nge of place in the
8tars, which ariaee (rom the motion
fixeel
or the earth combined
with the motion of light.
AcMnuJr, a fixed star of the first magnitude, in the
CODstellation ErUlaft..., B. A.. 1 bour 31 minutea.-Dec.
58 degrees, 16j- minutes•
.Achromatic, oolorl888, remedying aberrations of color.
Aclwo,&ieal rising or letting of a planet, or star, is whNI
it rises at 8unset, or lets at sunrise.
Aerolitu, or air.stones, are semi-metallic Iubstanoee,
which are found to faU (rom the atmosphere in different
countries. Some philOlOphers have imagined that they
are the fragments of a planet that had beeD burst asunder.
~ . . . .A~baratl, a fixed star of the first magnitude in the
... bead of the constellation Taurus; sometimea called the
Bal(. eye.
AIfol, a star in Medusa's bead, which varies from the
I8COm to the fourth magnitude.
.
Aliat/a, a fixed star in the tail of the Great Bear.
AlttJir, a star of the fint magnitude in Aquila.
AltitwJ,e, the height of the 8UD, mOOD, or stars aboTe
the horizon, reckoned in degrees and minutes, OD a verti.
cal circle.
~ mpAUcii, a Dame giTeD to the inbabitants of the torrid
• .Th. Gla.ary • copied ,lorn English worb Jatel, reprinted ia
tlli. CODay. and reviled 'to adapt it to the capacity of the JuyeDile
Leamer. The z."guage of the definitioD8 ii, iD IIOID8 iJultanc., dif.
fenat from that UIed in the precediDg papa, and a lew tel'lDll are
iDIerted aad defined that do DOt occur in aDY of the 181l0III. But
theae circolDltancel will rather eDhance than depreciate ita niue, u
they aecure an agreeable yariety where the meaning iI the ame ; wiD
..tt~ulate the IDYeaigatioD of eubjecta not yet 1lDclenIoocI; aad mat
. . . . to adcIi&ioDal I.earch in fields Dot yet ezplo:ed.
1;~
206
APPBN'DlX.
zone, on aooount or their shadows falling at one time of
the year towards the south, and at another time towards
the north.
.
Amplil:ude, an
of the horizon, contained between
the-east or west point of the heavens, and the centre of
the sun or a star, at the time of its rising or setting•
.Arulronaetla, a female, a northern oo~~eUatioD, containing 66 Itars.
AntlaU"', a ring.-Anau.,rioga.-AMulGr, ring-like.
AfIOfIUIlou, irregular, 8trange, out of rule.
.
Anomaly, (the true,) the distance of a planet in signs,
degrees, &0., from that point of its orbit which is furthest
Crom the .un. The mean anomaly is, that which would
take place if the planet moved uniformly in the circum..
ference of a circle.
AntiR0U8, the Youth, a part of the constellation Aq nila.
Antipode., those inhabitants of the earth who live dia.
metrically oppoeitq to each other, or walk feet to feet, on
opposite sides of the globe.
Ant6eci, • Dame given to thOll8 inhabitants of the earth
. who Ii ve under the same meridian, aDd at equal distances
from the equator, but OD oppoGte sides of it.
ApAeliOft, that point in the orbit of a planet in which it
is at its greatest di8tance from the sun.
Apogt" that point in whicb the lun, or a nlanet, is fur.
thest distant from the earth.
Appr~mtJte, next, near, approaching.
.
. Apsidu, the two most remote points of a planet's orbit,
otherwise termed its aphelion and perihelion. A line
joining those pointe is, the line of the apsides.
Arcticu, a star of the first magnitude in the Great Bear.
..drcturu, a bright atar of the ii.rat ,magnitude in the
arc
constellation Bootes.
Armiliary.-rp1aere, an instrument composed
or the prine
ciprrl circles which are drawn on an artificial globe •
.Ascii, the inhabitants of the torrid zone; so called, be.
cause the sun being twice a yea r in their zenith, their
bodies at those times cast no shadow.
Aapect, situation of the stars with respect to one an.
otber, or the planeUJ.
I
•
APPBNDIX •
207
.AsteroitU,the eight planets lately discovered moving in
eccentric circles between the orbits of Mars and Jupiter.
A8tronor11y, (trom A.tler, a star, and Nome" a law,) the
science which teaches the motion, magnitude, and distances of the heavenly bodies.
A.ttraction, that inherent principle of matter by which
bodies mutually tend towards each other, or to the centre
of the earth.
.
Am, (aze.t, plural,) of the earth or of a planet; an
imaginary line passing through the centre from one pole to
another, round which they perform their diurnal rotation.
Azimutu, great circles which pass through the zenitb
and Dadir, perpendicular to the horizon. The azimuth
a celestial body is an arc or the horizon contained be.
tween the east and west points, and a vertical circle pa••
iog through the centre of that object.
.
or
Bellatriz, a star in Orion.
Belt., zones surrounding the body ot Jupiter and Saturn.
Bet.elgue,e, a star in Orion.
Binary, double, consistin~ of two.
Bi88eztile, (or leap year,) which alappens every fourth
year, and contains 866 days; one· day being added to the
•
month of February.
Capella, a star of the first magnitude in Auriga.
Cardinal puint. of the compass; the east, west, north,
and south points.
Cardinal poin" of the ecliptic; the first points of the
signs Aries, Cancer, Libra, and Capricorn.
Castor, one of the Twins, a star of the first magnitude
in Gemini.
Cenlauri, the Centaur, (half man and half beast,) a
southem constellation.
Centrifugal fOrce, that (orce by which any revolving
body eDdeavors to fly off from the centre of motion in a
tangent to the circle it describes.
CentripetalfMce, the tendenoy which a body has to the
centre of its revolution.
Circumpolar, signifying such stars. as being near the
208
UPDDI%.
pole, moTe aroand it. They eet below the horizon in our
latitude.
•
Col.,.u, two imaginary ~ircles, or meridi8D8, one or
which palSBli through the solstitial points Canoer and
Capricorn, aDd the other through the equinoctial pointa
Ariee and Libra.
COtIIeU, erratic bodies belouging to our system, which
move round the BUD in very eccentric orbits, distinguished
by their fiery tails and nebulous upeets.
Ccnae, a body with a circular hue declining to a point,
like a sugar-loaf.
Ctmical, form of a cone.
Conjuru;timt, is when two or more stan, or planets, are
in the same part of the heavens.
C.OfI8IellatiorJ" or .A.sterism, certain figures delineated in
the heaveDs by the ancients, and also by the modems,
within which the principal stars are included for the pur.
plI8 of better finding and describing them.
COII8titueftU, ~rts composing and essential to the whole.
Conni,cal rising or setting of a planet, or stal, is when
it rises with the sun in the morning, or IJets with him in
the evening.
Cry8talline 1ae4"tm8, the solid spheres by means of which
the ancients attempted to account for the apparent motioD8
the fixed stars.
:
Cuap8, the .points or horns of the o)oon or of a planet.
Cycle of t1uJ moon, Ii revolution of nineteen years, in
which time the conjunction and lunar aspects are nearly
the same as they were nineteen years before.
or
Day, (solar,) the time between two successive transits
of the 8un's centre over the. samf' meridian, which always
begins and ends at Doon.
.
Day, (sidereal,) the time which elapses during tbe ro.
tation of the earth Crom one star till it returns to the
same star again, and consists of 28 hours, 56 minutes, ,
_conds.
DeclifJ4tian. is the distanoe
or any celestial object north
or south from the equator, reckoned in degrees, minutel,
&c., UPOD 8 cjrc~e which is perpendicular to it•.
. l
209
A.PPENDIX.
Degree, the 860th part of a circle; or the
a sign.
8~tb
part
or
Diagram, figure or representation used {or illustration. \
Digit, the 12th part of the sun's diameter, which i.
or
used in the calculation
eclipses .
. DUe of' the sun or mOOD. is its round face, which, on
account of the great distance of the object, appears flat.
Diumal motion of the earth, its rotation on its axis.
Dorpat or Dorpt, a town of Riga, Russia, where a University alid Obse"atory were established and Ii berall y
endowed in 1802. .
•
Eecefrlricilg, the distance between the centre of a planet's orbit, and the roous round which it revolves.
Eclip88, a deprivation of the light of the SUD, by the
interposition of the moon; or of the light of the mOOD, by
the interposition of the earth.
Ecliptic, a great cirole in the heavens through which
the 8un apparently makes his annual. revol UtioD; but
which is in Teality the earth's path.round the sun. It
makes an angle with the equator
23 degrees, ~8 min.
·
utes.
EltiIJorated, produced with labor, improved by succes.
aiTe operations.
'
Ellipticity, likeness to an oval.
Elongation, the angular distance of a planet from the
.UD, as it appears from the earth. It is applied only to
the interior planets, Mercury and Venus.
Emerrion, the reappearance of a celestial body. after
having been t'clipaed.
Epoch, particular period of time, period from one date
to another.
•
Equation of time, the difference between real and apparent time, or between that shown by a true clock and
a sun.dial. It depends on the obliquity of the ecliptic,
combined with the unequal motion of'the earth in its orbit.
Equator, or a great circle of the earth whioh separate.
the northern from the lOuthern hemisphere.' When re·
ferred to the heavens, ,it is oalled the Equinoctial.
Equinoctial, or Celestial Equator, the imaginary circle
or
.
IS-
210
~B!fDIX.
in tbe heaTens described by the sun in its daily revolution
at the time of the equinoxes,~r its apparent passage over
the line, when days and Dlghts are equal allover the
earth; the centre of the ecliptic.
Equi~J two opposite points in Aries and Libra.
where the ecliptio outs the equinoctial. W.hen the aUD
is in theae points, the days and nights are equal to each
other.
E"olutiora, unfolding or unrolling of any thing
Ederior plane"" those which move at a rurther distance
from the 8un than the earth j as Mara, Jupiter, &0.
Poci of an ellipse, two points in the longest, or transTerse axis, OD each side of the centre; from each of
which any two lines be drawn to meet each other in
~e ciroumference, their sum ·will be equal to the traD8verse axil.
ir
Gala:q, or the Milky Way, a luminous and irregular
zone which encompasses the heavens, whioh is found to
be composed of an immense number of stars.
Geocentric place of a planet, is that position which it
hlB when seen from tbe earth.
Gihbmu, a term used. in rererence to the enlightened
put of the mOOD, (rom the first quarter to the full, and
from the full to the third quarter.
GraD;", or Gravitation, that force by which all ma. . .
matter tend towards each other.
or
Halo, a luminous circle round the body
mooD.
Heliacal rising
or a star, is "hen
or the IUD or
it emerges from the
sun's raya, and appears above the horizon before him ia
the morning.
Heliacal setting of a star, il when it is 80 hid in the
lun's beams as not to be seen above the horizon after
him in the evening.
Heliocentric place a planet, is that in whioh it would
ap~8r to a spectator plaoed in the sun.
HemiqAertJ, the half of a globe or sphere.
or
UPBN'DIX.
211
BeUtwcii, a name given to the inhabitants of the tem.
perate zones, because their shadows at noon always faU
one way.
Hori'ZMI, (the sensible,) a circle which separates the
risible from the inYUdble hemisphere, and forms the boul'.
dalY of our sigbt.
H~Oft, (the rational,) a great eirc1e which is parallel
to the former, and whose poles are the zenith and the
nadir.
Hour circk8, the same as meridians-marking the
hours.
1W1merBiOft, the moment when an eclipse begins, or
when a planet enters into the shadow of the body that
eclipses it.
1ncli:tuJtitm, the angle which the orbit o( one planet
makes with that of another, or with the plane of the
ecliptic.
Interior plane"', those that move at a less distance (rom
the sun than the earth, which are Mercury and Venus.
Irre801'Oable, incapable of being analyzed, defined, or
perceived as distinct objects
Latitudt of a place, its distance from tbe equator, reck.
oned in degrees and minutes upon the arc o( a great
circle.
Latit,u,tk of a star or planet, is its distance from the
ecliptic, reckoned in degrees, &c., on the arc ot a great
circle.
LeOflb, a star in the constellation Leo or Lion.
LeIJ8er circle. of the same sphere, those whose planee
da not pass througb the centre, and which divide tbe
sphere into two unequal parts. Great circle. of tbe equator, meridians, &e., divide the sphere into two equal
parts.
Li1wation the moon, an apparent irregularity in her
motion on her axis by which we sometimes see moft
than the usual half of her disc.
Longitr'de of a place, its distance east or west (rom the
first meridian, Feckoned in degrees, &c., upon the equator.
or
212
APPBXDIX.
Longitude or a star or planet, its distance rrom the first
point or Aries, reckoDed in degrees, &c., upon the ecliptic.
~, a body giving light, a celestial body.
lM1I4I', rela~ to the moon.
LUIItJtion, the time between one new moon and another;
which is, on an aTenge, 29 days, 12 bours, 44 minutes,
a leCOoda.
~
dark spots which appear on the face of the
Bun; and Pacrik are bright spots sometimes seen on the
101ar disc.
Ma,e!J,a,nic clotuU, certain whitish appearances in the
heavens, in the southern hemisphere, supposed to consist
either or an immense number of stars or nebulm.
MtJBfIitude&. The stars are divided into six classes; the
brightest are called stars of the first magnitude; the next
in b~htne88, the second magnitude, &c.
Mea motion of a planet, that which would take place
ir it moved in a perfect circle, and equally every day.
Meridian, a great circle of the sphere which passes
through the zenith and the poles, and is perpendicular to
the borizon.
Meteor., transitory luminous bodies in the air or sky.
Micrometer, an instrument fitted to a telescope to measure Tery small angles; as the diameters of the planets, &c.
MicT08copic, relating to the properties of the microscope,
-an instrument for magnifying small bodies by an are
rangement of glasses or lenses,-to be seen only with the
rmc~pe.
.
Milky Way, Via Lactea, or Galaxy, the broad white
path or cloud, seen as 8uch by the naked eye, and vary.
ing in width from 5 to 16 degrees, but found by the telescope to consist of innumerable stars, (8 or 10 millions at
least, l and . assemblages of nebulm and closters
stars,
the mingling light of which evolve whiteness.
Mythological, relating to the fabulous, though 80metimea
beautiful stories and theories of tbe ancients.
or
Nadir, that point in the heavens directly opposite to the
zenith, or imm~iately under our Ceet.
,
APPENDIX.
213
N,1Ju1a, luminou8 sPots in the heavens, or clusters of
amall stara, discovered by the telescope.
NocturMl arc, that space of the heavens which the SaD
apparently describes from the time of his setting to hi.
rising.
NOtk8, tWO-points where the orbit of the moon, or of a
planet, interseQts the plane of the ecliptic.
1Vucleu, a term used to denote the head of a com~t.
Oblique tuctmBitm, an arc of the equinoctial contained
between the first degree of Aries, and that point of it
which rises with the centre of the 8un or atar.
Oblique Ipilere, that position of the globe in which either
or the poles is elevated above the horizon any number
degrees less than ninety.
Ob.eroatory, a place or building fitted up and provided
with proper instruments for observing celestial bodies.
Occultation is wh~n a star or planet is hid from our
Bight by the interposition of the moon or some othel planet.
Oppoaititm, an aspect of the stars or planets when they
are 180 degrees distant from each other, marked thus, 8.
Orbit, the oune which a planet describes in its revolu.
tion round the SUD.
Orrery, a machine to represent the motioDs of the plan.
etary bodies, 80 named in honor of the Earl of Orrery.
08cillatory, moving backward and forward, like a pendulum.
or
Paralla:t, the difference or the place or any celestial
object 88 seen from the surface of the earth, and (rom ita
centre.
Para'lloz
of t1ae
eartA'. amaual orbit, the angle at any
planet 8ubtended by the distance between the earth and
the lIun.
Parallela of latitude, small circles of the sphere which
are dra WD parallel to the eq nator.
Penumlwa, a faint shadow observed between the perrect
shadow and the full light in an eclipse.
. .
Perigee, that point of the solar and lunar orbit which
is nearpst the earth.
,
•
214
UPBNDn.
Perilaelior&, that point of' the orbit of a planet nearest
the
8UD.
Pemcii, the inhabitants of the frigid zones,
named
because their shadows go round them ror six months, or
fall towards opposite points of the compass.
Perturbation, disturbance, disorder, disquietude.
Pluss, the different uppearances of the illuminated
_
parts oC tile moon or planets.
PkeflO'lMftOf&, any extraordinary appearance in the
heavens, 8S a comet, &c.
Planetarium, an astronomical machine for showing the
motions and other phenomena of the planets.
Planetary, relating to planets.
Pleiadel, or the seven stars, aD assemblage
stars in
the constellation Taurus.
.
Polar circles, two small circles, 23l degrees from the
poles; the arctic in the north, and t6e antarctic in the
BOuth.
Pole 814,., a star of'tbe second magnitude in the tail or
the Little Bear; so called, because it is near the north
pole.
Prece8ritm of tile equi".el, a slow motioq
the two
points where the- equator intersects the ecliptic, which go
backward about 50 seconds in a year.
80
or
or
Quadrant, the fourth part of a cirCle; or an instrument
or
(or measuring angles, and taking the altitudes
the SUD
\ and other heavenly bodies.
Quadrature, that position of the moon when distant 90
degrees f'~om the sun; as in the first and third. quarters.
Badia Vector, a line supposed to be drawn rrom the
centre or any planet to the centre oC the sun, which, moving with the planet, 8escribes equal areas in equal times.
Refraction, the bending of the rays or light in passing
through the atmosphere, by which the heavenly bodies
appear mOTe elevated than they really are.
Refrangible, capable of being bent or tumed aside.
Regula, a star of the first magnitude in the conltel1~
lion Leo.
,
RuoZ"dle, that
215
.l..P1»BNDIX.
whic~
may be analyzed, brought. together and explail)ed or defined.
Retardation, hinderance, act of delaying.
R",."ade, an apparent motion of the planets in 8O~e
parts of their orbits, when they seem to go backward, or
contrary to "the order of the signs.
Right a8cenaitm is that degree of the equator which
cornel to the meridian with the sun, mOOD, or star, reck.
oning Crom the first point of Aries.
Rotation, the motion of any heavenly body round ita
axis.
"
&tlllile8, secondary planets or mOODS, which revolte
roWld the primary planets.
" "
Selenograp1ay, a repre~Dtation of the moon, with a deacription oC her different spots and appearances.
s.tik, an aspect of the heavenly bodies, when they are
60 degrees distant from each other.
Sidereal, of or belonging to the stars •.
Sign, the twelfth part of the ecliptic, or 30 degrees.
Sina, "the Dog Star," one of the brightest in the
heavens, is in the eODstellation Canis Major.
Solar, relating to the sun.
So18titial pointB~ the first degree of Cancer and Capricom, at whioh the ecliptic touches the tropics.
SpAere, the concavity of the heavens in which the atara
appear.
Sphericity, rotundity, roundness.
Spica, a atar or the tirst magnitude in the constellation
Virgo.
"
.
Star Dul, clusters oC small stars appeariDg like sparkling land.
Stellar, relating to stars.
""
"
Sy6letlt, a Dumber of bodies revolving round a common
~ntre, 88 the planets round the sun.
.t )1" ',. ,"
SY:1gy, a term ~ually applied to the ~~R,.'rip~~' 'in
opposition or in conjunction, or when at t~"H'Yc .9 r ,fWl.
['('If! I
• ~
'\
Telucope, an optioal iDstrument eo, the,;P~f~ or,vj~~
ing distant 'obiects, particularly the IU~ W90~i' 'pl~H~m.
216
APPBKDIX.
and Italll. Telescopes produce their effects e.:ther by
refraotioD through glasses, or reflection from speculums.
Telucopit; 8tar6, those stars which are only visible by
meanl of telescopes. All stars beyond thoee of the sixth
magnitude are reckoned telescopio stan.
Torrid zone, that part
the earth whioh is contained
between the two tropics.
Trajectory a term applied to the orbit a comet.
TraMit of a planet denotes its pa.ing oyer another
planet or star, or aoro. tbe disc of the 8un.
Trine, an aspect of the planets when they are 120 de,rees distant {rom each other.
Tropia, two circles parallel to the equator, and 23 degrees 28 minutes distant OD eaoh side of it. They are
Ilamed Cancer on the north, and Capricorn on the muth.
or
or
Vertical circle., the same as azimuth circles, or .ucla
as are drawn perpendicular to the horizon.
Prime W11ictU, is that azimuth circle which passes
through the east and west points or the horizon.
Year, (the solar,) the time which the
IUD tak~
to p888
Crom one tropic till it returns to the same again, and is
865 da Y8, Ii hours, 48 min utes, 49 sooonds.
Year, (sidereal,) the time which the sun takes to pass
Crom any fixed star to the same again, and is 885 daya,
6 hours, 9 minutes, 9 seconds.
Zenitl, that point or the ·heaveos immediately oyer
head.
Zodiac., a zone surrounflirlg the heaven., 18 degrees
broad, in the middle of which is the ecliptic. . The orbits
of all th~ old planets are included in this zone.
Zodiacal, relating to the Zodiac, great circle of the
8phere, signs, &c.
.
Zodiacal light, a brightoess sometimes obae"ed in the
heavens, somewhat similar to the MilJtr, W ay.
Zone, a division the sphere betweed two parallels at
latitude. There are fiye zonel; one torrid, two temper•
.,18, and two frigid.
or
QUESTIONS
ELEMENTARY ASTRONOMY.
BY H. MATTISON.
LBeSOM L-WBAT do we undel'Bland by the term .eime,1
What is utnnltnR, 'I How do the son and moon compare with each
other in their apparent· ••, 'I How with the other heavenly bodies 1
What ditFerence in their liglt'l What· Mid of their change of POfttion with respect to each other1 What said of the different appeartJflee. of the mOOD 1 What remark respecting the 1&onu of the olel
and Dew moon! In what directitm does the mOOD actually 1(0; and
how is it 88Certained 1 What Rid at ber enering, or Ob8CUnftg, the
etars 1 What of the Uric line. or Hurd upon her face 1 Wbat is
an ,elip.? Hal'e you eyer seen one 1 Was it of. the "", or moOfl?
What laid of the apparent me of the stars 1 What of their relative
fIOfttiou1 What exceptioD8 to their general apparent fixedness 1
What in-'pltJrity is obae"ed in their motiona1 What Rid of the
fIUW1&iftg and ,wai.g 8tar 1 Of the staN about the North Pole 1 Of
the eluJng. of the
pHition, from winter to II1IIlmer, &C. 1 May
all the p~enomena thua far enumerated be obeerved by the fUJked ,ye,
or without teleeoopee 1 How did the aftcimt. lItudy astronomy 1 Of
what is the leieDce of utronomy compoeed, and how HI it constituted t
"fl.'.
a.-Where do we find the oldest recorda of utronomieal science 1
What clU8teftl of Itar8 aN there mentioned, and in what books 1 How
doee the Bible J'eprel8Dt the earth 88 upheld 1 What Greek philosopher taught utronomy before Christ, and who in the second century
after Christ 1 What W88 Ptolemy's theory called t Where did it
locate the earth 1 De8Qribe the Ptolemaic theory in detail, and illustrate by the ma~
a.-Were there any special difticultiee in the theory of Ptolemyt
What is the fir., mentioned by JOur author1 What ia the 8tcontJ1
What ill the ,Aird, anel how , it illustrated 1 What is the fOJl,rtil and
last diftioulty named 1 What woold be the hourly motion of the
upon thil tbeory 1 jlpw Iwiftly would it require the nearest ped
.tar. to move 1 ~ucb an abBord theory ever generally believed ,
How long did the doctrines of Ptolemy prevail?
.u.
218
aU.BN'IA.BY ASTBONOMY.
~-Who originated the preaent generally received syatem of lUItronomy? About ",bt tirM 'I What is this theory called, and why 1
How dOM thilllJ8iem aecoODt for the apparent daily motion of the
.un, mOOD, &0.. tiom eut to west 1 Do we ever suppose objects to
move that are at real, .amply beea. . . . are moving? Give aD illustration. Where doea the Copernican theory place the .un 1 Wha.t
two motions doee it attribute to the Dumeroul worlds that 8UlIOWld
him 1 What doea the first of these motiona produce, or cause? What
the I8CODd? What map illustrates this theory 1 Where is the 8UD
Men on the map 1 Where the p1aneta, and hed &tara1 What is
meant by the orbit of a pJanet, and how repreaenteci on the map 1 In
what direction do the planets move around the IUD 1 How indicated
OD the map 1 What particular fact is referred to .. evidence of the
truth of the Copernican theory t
.,.tem
a.-What are the fiIIIt grand dil'ili0D8 of the 1lDivene 1 What is
meant by the 101M'
'I What by the . . . . .1 "~tft)eftl 1 How
is the lormer situated in reapect to the latter 1 Which of theee, grand
diYirioDa Is m.t eoMidered by your author 1
••-From what doee the eoIarllfBlem deriTe ita ~ame? What are
the bodiea of our IIJ8iem called, as a whole 1 How are the BOlar bodies
6IIt divided 1 How is the Bon distinguished from th~ planets? The
planets from the BUll? What does the term planet ngfti/y ? How
are the planets d;,,;ded'l What are the prifUrie., l)eecribe the
eeeontltwUJ.. Point oot. each OD the map. •Which are the itaim.
planeta, and wby? Which the esttrior 1 What are the ..teroilU?
What are t:tmaet., and how distinguished? Poin. out the clliFerent
cla.ea of IOlar bodi. on the map.
pltJ.,.
V.-How many fWi"'tJrY
are there? What are their
tatJtnd'l Wltat are they generally Damed after 1 In heathen mythology, who wu lfIercury, and what does the astronomical sign of
this planet repreeent 1 Who wu Ven•• , and what is her aigo 1 What
two ligos repl'e8eDt the Bartl 'I Who W81 lfIar., and what iB hial
.ngn t Deecribe V uta, and her lip; A.trea, and her sign; Juno,
and her 1Iign; Cer••, and her lign; Palla, ·and her sign ; Jupiter,
and hie sign. What il the origin of the sign of J opiter? Deseribe
Bat"'NI, and hi8 sign. FlOm what did Her.cla,' derive his name 1
What other namel haa he 1 What constitutes his siln': From whom
does
Verrie'1· derive hill name? Of what is his sign compoeed?
What Dame did the Board of Longitude of Paris recommend for thiB
planet 1 Can you make the Bips of the different planets UPOD th6
black-board? [The clua showd here abake and explain the diit8r.
eat lipl, in cODII8CDtive older.] Make the trign for "~ID, Iudf-".-n,
and full IIIOOfL The IIigDa of the IUB. What doea the first repre_at 1 Find the 8everal primary planeta on the map. When mouid
Le VerrUr be placed 1
u
~
..
•
QUBSTIONS Foa UAXllIATION.
219
What is the .cale of flu.
employed OD the map? Give the diatancee of the several
planets, comnlencing at the BUD. What Baid of conceiving justly of
vast distances 1 At the rate of five hundl'ed mil.. per hour, how
long ould it require for a body to paaI from the sun to Mercury 1
How long from the IUD to our globe 1 How long to reach HelllChel?
What illustration employed 1 How long would it take for a train of
ears to pass from the sun to Mercury, at thirty miles per hour 1 To
our globe 1 To HellChel1 To Le Verrier? How illustrated by refere.Dce to Whitney'8 proposed railroad 1 If a train of C8l1l had left the
SUD, at the creation of .the world, to visit the orbit of Hel'lChel, where
would they be now 1 How much longer would it require to finish the
journey 1 To reach the orbit of Le Verrier 1
8.-What is the subject of this lealOD 1
ttJ1&CU
8.-What is the subject of thia Ia.on? What i8 a circle 1 A
. qUGT."t 'I A 8ezta'llt? A Big'll 'I A degree 1 A minute 1 A
~cOftrll
mnstrate these several divisions of a circle, by the map.
How P,iany degreeS are there in a circle 1 Have all circles the _me
nuwber of de~ees1 l\tlake the 8igns for degrees, and minutes, and
BeConds. What is measurement by degrees, minutes, ·and seconds,
called 1
I
1O.-Giv& epmples of anpar measurement, distance8, diametel'l!l,
alti.tudes, and velocities, from the map, Fig. I. How does the flutance of the observer from an object eiFect ita apparent magnitude,
&c. T How ill thit illustrated by Fig. 21
ll.-Upon
th~
principJee of the preceding le8lJOD, how would the
8OJ1 a.ppe~, viewed from Mercury 1 From Vena 1 From Le Ver ..
1 ~rom Sir;'IU? What is the angular diameter of the BUD, lUI
vie.wedfrom our globe 1 What would it be from Mercury 1 From
JUliter 1 From Her.chel? From Le VefTier 1 What idea o~ the
distanc, to Le Verrier would arise from the diminutive appearance of
the lun, if viewed from that point 1
ner
lA.-What
is the I1lbject of this )elBOD 1 By what rule do we
determine the 1'8Jative amount of light received by bodies placed at
unequal distances from their luminary 1 H~w is th.. rule illustrated
by Fig. 41
18.-By applying the role of the preceding 18llODB to the planets,
aud 8upposing the light and heat of each to be proportionate, what
would be the r,'ati,,~ light and heat of Mercury, Venus, &c.? What.
then, would be the average temperature· of Mercury 1 Of Veo.. ·r
Of Jupiter? Of Saturn 1 Of Hel1lChel1 Of Le Verrier 1 II it certaiD_
that the light and heat are proportionate upon the several planeta 1
What said of the te1nfJerature of Mercury? What of the temperature
of Jupiter, 8aturn, H ••chel, aDd IA Verrier 1
"1
120
RLS• •KTAaY
~ONO.Y.
1"-What ill the IUbject
of tllia ..... 1 By what acaIe are the
drawn OD the map 1 .. the IUD drawn upon the la1De acale 1
y not 1 Giye the . . . .w. of the .vera) pluets, beginning at
Mercury. Do the rela&iYe" on the map 888m to etIITttepoRtl with
til. . diameterw t At fotty tho.aad milee to an inch, what should
be the diameter of Satam, on the map, aocordiDg to the table of magaitud. t What mould be the diameter of the earth t
~be..
JA-Of wbat doea tbille.oJl treat 1 What ill the scale o( map 41
What ia the actual diameter of tbe _D, in mil.? At forty tbousaDd
miles of diameter to aD inch, how Iarp must he be drawn to correa- .
poad with the other pluetl t What is the b.lk of Mercury, 88 compared with the earth t Of VeDUi t Of MBl'B 1 Of Jupiter 1 Of
8atum 1 Of HeJ'IIChel, ud Le Verrier 1 \Vhat iI the bulk of the
_11, u compared with our I(lobe 1 What u compared with the
whole aolar lyatem besides 1 How many global like ours would
it. take, if laid lide by Bide, to reach acJI)88 the IUD'. diameter 1
What illustration of the lUIl'1 magnitude is drawn from the moon'l
ntl
1•.- What i. the IUbject of thillellOn 1 What is meant by tkrt-
.'y
1 Give examplee of lubatancee or diftereDt deDSities. Have all
the pluetl the ..me deDlity 1 GiYe the de_ty of the levera) plan. ., 88 compared with the earth, aDd the lUb8taBcee with' which they
ID08l nearly epee in weight.
IV.-The aubject of thille110D 1
What iI meant by grtIfJita.titm 1
What COD8titutea the lIJeigAI of bodi.l Upon what does the amount
of weight depend 1 Do luge bodiee .l••g. attract more strongly
thau small ones 1 Why not 1 Do the planetl dift8r in their attractiYe
force 1 What would a body weitrbiDg one pound on the eartl&, weigh
upon Mercu,., 1 Upon VdU, &c. t What upon the "'" 1 Wbat
.aid of the attractive force of the ..teroitU 1 Is the attraction of
the planets in proportion to their bulk 1 Why not 1
18.-What iI meant by the ~dit: rnolalio" of a planet 1
What
give tbe periodic times of the aeyeral
plauets 1 What coastitatal a planet'. ,car 1 Do all the planel8 mOM
with the MIme Nlocity 1
by ita periodic tUM 1 Cu
Y011
U.-What ia the lubject of th. le.oD 2 Can you give the hour11 motion of the leVeral plane.'
".-What is meaDt by the centripet.l force of a planet 1 What
by the centrifugal 1 What would be the result were the centripetal
toree .uqeadetll What if the centrifugal! Why doea Mercury
JeyoIye more rapidly in his orbit than any oth. planet 1 Why do
the more distant planets move 10 1I0wly t What particular fact Ie-
,
Ql1BSTIONS POll BLUlINATION.
221
8pecting the motions of the planets is mentioned u exhibiting the ...dom of God 1
AI.-Have the planet. any revolution' except around the IUn?
What .. it called in the caption of tbis le&80n 1 What natural pheDomena are produced by the revolution of the planeta upon their &%68 ,
Recite the time occupied in the diurnal revolutjon8 of the several
planets, 80 far 88 known. What do you observe 88 rather remarkable
respecting the fi1'8t four planets 1 What peculiarity in the time of
Jupiter and StJturfl ? How many days have Jupiter and Saturn in
ODe of our ye81'll1 How many has Jupiter in one of Ai. years 1 How
many has Saturn in one of Ai. years 1 How waa it ucertained that
the planets had a diurnal revolution 1 Has the motion of the planets
'on their axel any eJFect in modifying their form.?
aa.-What effects would fol1ow if the planets were culM. instead
of globe. 1- Are the planets exactly spherical in their forma 1 What
is their true figure T Where is their diameter greatest 1 What
causes this flattening or oblatenesa1 What is the di1Ference betwee.
the polar and equatorial diameter of the aeveral planets 1
fIa.-Wbat is the ecliptie? Point out the ecliptic on the map.
Why is the eartb represented of different siles1 What said of her
pAtUe., color, &c. 1 What do the arrow. set in her orbit indicate 1
What further'ilIustration of the ecliptic is given by the author 1 Are
~e SUD and eurth always in the plane of the ecliptic 1
a..-
What are the pole. of the earth 1 What the pol. of the
ecliptic '-'!"- How illustrated by the pointer and map? A.;e the ecliptic and tbe eartA'. 'qtuJlor in the same plane 1 How, then, with
their pole. 1
• •-How dOe. die ecli,tic lie with respect to the earll'. equ&,or? How d08l this affect the position of the .un at di1Ferent 88880_
of the year? Does the plane of the equator pass the ecliptic perpendieultJrly or obliquely? What angle is included between them?
I
What is this deviation of the ecliptic from the plane of the equator
called 1 Can you illustrate this subject by the map?
....- What is the Zotli4c ? How ia it represe~ on the map t
What portion of the heayeDa does the Zodiac include 1
av.-
The .u1Jject of thil leIIOn t How is the Zodiac ditJiiletl1
Bow are these diviaiOD8 shown on tbe map? What did the ancientl
imagine respecting the stuB of each sign? Wha.t are the name. of
the twelve signs? Can you make their .ymboZ. on the black-board 1
What notion had the ancient utrologift. respecting the signs? Are
there any that BtiU hold to thia idea? Ie it correet 1 What do theJ
BLBJDNTAay ASTaONOXY •
.... 10 UDClerItaDd bJ the ..ont " . . 7" What iI ita true meaai.
ill AatroDomy t
aa.-Its .abject 1 What doee Figure 1 on the map zepreaent?
What ia the plane of the ecliptic 7 [23] How lIWly times muat a
plan~t pua tbrourh the ecliptic at each revolutioD 1 What are the
poiDti caUed where a planet cutl the ecliptic 1 How are the nodes
&tinguilbecl1 Can you make the utronomical lip for eacb"
What • meu.t by the lilae 01 tile JIDda 1 PoiDt it Ollt on the IDap
In the _ure, where ia the A.:,,,tli"l1 Node placed .. respects the
Wbere the tU.cmtlinK 1 Doee the fipre -repreeent the actual poeition of the node. of any planet'. orbit t
.,081
"'."t
. . .- What iI a
1 Which of the planets make traD8itB
oyer the 81ID'. diIc gible to us '1 Why do not the other pillneta 1
What pluebl would make tnuuit. if we were placed upon Hencbel1
Where mOlt the planet making the traoait be, at such time, ia reI!p8Ct to the nodea of itl orbit 1 How with the obeerver t
Wby do
aot the i.uer1tw planets make traoaits at every conjunction with the
IUD 1 How could this be etFected while their orbita do not coincide
with the ecliptic 7 How are tranaita calculated" How often can
Ibe Earth aDd Mercury meet at the same node 1
8O.-Subject " In vut fIIORtu do aU the trausits of Mercury
occur 7 W!ty is thi." At which node do hi. Ntm,mb. transits occur 7 His May transita 7 Do the f.raD8its in the table conform to
tbe ratio laid down in Le.on 29 1 Did you ever lee a transit 1 Wben
doeI the next traoait of Mercury occur I
81.-Subject'1 Bow many revolutions ofVenas equal eight of the
earth 1 Can you state
of the other periods in tbe table 1 Where
. . the liM 01 Vs"" ..de. lie 1 Wben does the earth p. . these
peinta in the ecliptic t What fact fonoWil from the lut-name1l
circumstance t When doee Venus make the next \nmsit t How
mauy, yet to occur, are laid down in the table 1 Are those predicted
to occur in accordance with the ratios given at the commeDcement
ef the leaJOn 1
anr
lSL-Subject'1 What do you undemtand by an ecliPft 7 [231
What are the orbit. of the planets t [4] What does Fig. 1 on (he
map repreeent 1 • Is any planet's orbit thus inclinoci 1 What does Fig.
I repreeent 1 Where is the Bun placed 1 What represents the EcLip.
tit: '/ What are eeen on the ript and left 1 What do the plain linee
represent. 1 Where do you find the names of the planets, IUld where
the amount of their inclination respectively 1 How mucb is the orbit
of Mercury inclined" That of Venua t Earth 1 (Tbink, now.)
KanJ, &0. 1 Wbat part of the map represents the ZodiGc 1 Where
do most of the planets' orbits lie, as respects the Zodiac 1 What ex-
QUESTIONS FOR BXAMINATION.
223 '
eeptiODS" Hence eomet!mea caUed what 1 What two objects are
seen near the middle of the figure" What di1Fel'8nce in their direction 1 What fact is this designed to illustrate 1
a.-Are
the equinoctial and eeliptie in the .a1M pla1U? At
what angle do they intercept each other 1 What is tnre.trial la'iCude? Is ctle.titll latitude reckoned from the equiftOctial or cele.tial
~quator? From what, then 1 What, then, is cele.tial ,latitude 1
What aeeming contradiction folloWi from tbiI fact"
a".-What is longitude on the earth 1 From ."hat point in the
heaveD8, and A.ow, is ceJestialloDgitude reckoned" What is the map,
as a whole, a repl'elJ8ntatioD of" How must it be placed to answer
to the Zodiac in the heavens 1 Show me where you begin to reckon
longitude on the map, and where you end. U Aries, {or instance,
were directly overhead, where would Libra be" What is the IoDgitude of the Twins; the Lion; the Balance; the Goat, &C. 1
aa.-Subject t In what ligu are the node. of Mercury'. orbit 1
Where and lunD ia this illustrated" Which Bide of the ecliptic is con_dered lUI aoo.,e, and which belo." 1 What, then, is it to aBcefUJ
above, or de.e,ad below it 1 What do the arroVJ. near the sun show '7
What the next pair" Why ia not the longitude of both Dodes laid
down in astronomical ~blee t What example does yoor allthor cite 1
Can YOIl give the longitude of the tUCending node. of the plan.
JNpectively 1
aG.-Subject 1 What is a eouteUation? Do the ng.. and eonlItellatiou of the Zodiac bear the Bame namea" Do the signs" gov8I'D" different pa11I of the human body, u stated in lOme almlUllICII 'f
What are tbe nelme. of the coustellatioDS of the Zodiac 1
,
aV.-Subject 1 What does Fig. 1, Map 5, represent 1 When
the earth is in Libra where will the 8t1D appear to be 7 As she paase.
around to Scorpio, what will the BlID appear to do 1 He~lce what doee
the sun seem to do ODce a yearl How is lb. illustrated by Map 61
What is the earth's longitude on the 20th of March 1 What sign
does the aun ~nter on that day 1 When does the 8Ull enter the different signs" Does he really mo.,e around the ecliptic 1 What,
then, gives him his apparent motion 1 Which are the Bpring signa,
and why 80 called" Which the
1 The autumTUJl? The
.inter ?
."""1Ier
".-Are there any Stan above UI in the daytime 1 Why do we
8e8 them" If we could lJ8e them would they be the same th~
..e noweee in the Ilight 1 What sta1'8, then, are above us in the daytime 1 Are BtarB ever visible iD the daytime 1 When 1 How 1
Why do the stars rise earlier rwd earlier every night froID year.l.o
DOt
BLBKBNTABY ASTRONOMY.
,ear' How do you illOltrate thia .abject by the map 1 What other
II8IB do you make of thiI map ?
".-Subject! Why are the names of tho tIIORtu placed 88 tb~
a~ OD the map 1 Do the months &Dei aigus .,.~e ift longittuk1
Which • entered fint, the new np or the Dew fIIOfItll What.
the difference of time 1 HoW' is this mown on the map 1
.y.-Subject 1 By what imagiDary IiDeII is the Zodiac divided!
Ilow distinguished on tbe map 1 What are the equiftDctial point. in
the earth'. orbit 1 Why 10 called? What. tho equi1lOc,iGl?
When doee the earth pall the equinoctial poi,:,bI t Bow are these
points diitiDgoilhed 1
G..-Subject 1 I. th. an easy or a difficult I.,.,n 1 In what
are the equinoctial points t What do you QIldel'8tand by the
" Prece"''' 01 tle Equinoze. 1" Ia it an actual preceuion of the
equinoxes, or a reee• .una 1 Do the equinoctial points, then, actual',
recede 1 What i. the amount of their anDual motion 1 Are the equinoctial points fixed points, then 1 What, tben, constitute the "erul
aDd autumna' equinoze. 'I What constituteI a fUlt.rlll or tTOpie,"
'I II the equinox reached before the earth has made a comple&18
periodic revolution 1 How much more time is requisite to complete
a nilereGl revolution t How long does it take the .un and equinoxee
to fall back a whole degree? Do the ftgu recede like the equinoxes 1
Which way do they seem to move from the equinoxesl . What doee
thi8 motion require in regard to mapa and celestial ff!0bes1 How
often does tb. recelBion of the equiDoxes amount to 30 1
ftgnB
,ttl,·
.a.-Subject 1 How are the lOl8tieitJl point. represeDted on the
map 1 When does the eartb reach the _",mer 8Oletice? Wbell8
does the nn leem to be tben ? When does the earth reach the winter solstice? Where is the IUD then? What causes tbe tlecliUhDa
of the SUD north and IOUth of the equinoctial?
.a.-Subjeet 1 What are the Colwe. 1 How are they distingui8hed, and why? How are they compared to meridians? How
do they divide the celestial sphere? How illustrated by hoopa 01
wire 1 What is gained by knowing the place of the colure. ill the
heavens 1
.a.-Subject 1 Upon what supposition bas your author p~
eO thus fa~, .. respect. the planets' ~rbits 1 , What is thE-ir true figure 1 Where ill this represented 1 Are the planetary o~bil8 all &lib
in this respect t What bodies have orbits still more eUiptical2 Whore
is the BUD found .. respects the centre of these elongated orbits t
Illustrate by the map. What. the point where the IUD is folUM!
ealled 1
I'
QUBSTIONI POB BUMINA.TION.
225
".-The .abject 1 What iI the periluliora "nat in a plUle".
orbit 1 What the sphelio1& 1 What do pmgee Uld spog" meaD in
respect to the moon 1 Point OIIt the periJ,..lioa aDd s,helion pointe
in tho earth'. orbit, on the map. What i. the dilerence between the
perihelion and tJpAelUm distance of a planet 1 What i. meant by ita
".." distance 1 Whicb distance i. given in Le.on 8 1 What do
you uDdentaod by the longitude of periieliGul 111 what longiwde is the ea.rtla nearest the sun 1 Can you point out upon Map 6
the perihelion pointe of the several planeta" accQI'ding to the long;'
lade given in the table?
.
• •- What i. the lobject of this leaIOn' What is meant by the
eccentricity of a planet's orbit 1 How illU8U'ated by the map 1 What
iii the eccentricity of the orbit of Mercury 1 or that. of Venus1 or
th. Earth 1 If the BUD is 1,618,000 mile. ODe lide of the centr, 01
the earth's orbit, M1D much nearer the aun iB tbe eartb at periAelilla
thau at aphelion? Which of the planetary orbits are tbe most olliptical? Which is the neare8t a circle 1
~.-Subject? How much is the ,srti'. as;' inclined to the
ecliptic? Where is tb. illustrated 1 What other fact ia iUuatrated
by the aame figure 1 When does the light of the IUD extend to both
poles 1 When have we the greatest amount of .uolight in the fUWlh..n hemisphere? Is it .ummer or winter here, then 1 . Where, on
the map, il the earth at tbis time 1 Where iI the eartb at the time
01 the wintn- aolstice? What bu the lun appeued to do betweeu
the lummer and winter 80Istices 1 What iI thU8 prodllced by hit
888ming change of position 7 Are we neareet the Bun in nm,ner, OJ'
in ."inter? Why, then, ia it Dot warmMt in thenortbem hemiapheN
in Decemlwr '/ How"..., the eccentricity of the earth'. orbit atFec&
ihe88880D81
".-Subject? What do yon undendaDd by the BlUl'. ""li.tilm 1
When dON he have ttOrtAern decliQatiOD 1 When ."thena? Wbat
ill his declination at the time of the eqainox.? WbeD i. it greateat?
What figureI illuatrate this anbject? Wbat dON Fig. 2 abow 1 What
farther iUUBtratiOD have we io Fig. 31 Point out the place of the .aD
at the .time of the wiater -ut.it:& Where ia be on the 20th of
March 1 Where on tbe 23d of September 1 Where on the 21st of
JW1e 1 Is he directly overhead then 1 How many degrees does he
lack of it, according to the figure8 7 What iI meant by the ~enitA
poiat'/ From all this, wbat do we learn respecting decli1UJtio-n '/
.....-Subject? What do you underataad by right lUcen"'?
Wbat is the equintlctiaZl [40] WIlerein doee c.le.titJllatitude diJFer
fiom twre.triGll What oelestial meuuremeutl, theD, 8D8wer to
latitude aDd longit.ude o~ thE' earth? Could you understand and remeinber tlecliutitm and rigAt MCeuitm better, if they were c.W
·
226
BLBKBNTAKY ASTRONOMY.
eel_a! "tu.tle and ltmgihltk'l What does your author thiak of
mch a chop of tel'DW 1 How many tkgreu of right 88C8D8ion can
there be 1 Wherein do rig'" fNCeuioa and cek.tilUloagitutk diWel't
aG.-What iI the ,eliptit: 1 What are the orbit. of the planets T
What .. the IAlbjece of I~n 32 ! What the subject of this lesson"
\Vhat doee your author ..y of thiB l.,.,n 1 What represent. portiOD8
of the planetary orbiu on the map t How are their leveral tlSU
Ihown? Ho.. their efl&dtor.? Their .OftU 1 Upon what does the
tztent of the torrid lODe or a planet depend t How does the sun'•
.ucliutio" north and BOOth of the equator, and polar iacli1UJtiou
agree 1 HoW' doe. the tonid zooe compare, in iu extent, with the
polar inclination of a planet 1 Do you no.. undentand Aot.O the incli.
nation of the UN of the planet. "cta the extent ad character of
their .on. 1 What .aid of Mercury, the 8IIte1'oid8, Henchel, and La
Verrier 1
,
Il.-Upon ..hat two C&UIM do the 8881OD8 of the planets depend 1
What doee the former determine" The latter 1 Illustrate by the
map. Have you reviewed I~D 461 [See quMtiOD&] Do you still
remember what is meant by the obliquity of the eeliptic 1 What do
YOIl undentand by tkclinatioa?
What .. the clliFerence between the
,cliptic and the e,Minoel",'?
'
6fL-Subject t How far are Venu' tropics from her equator 1
Hu she a frigid zone' What aid of the 8UD'. dPClinatiOD upon
Venus? Of her Ie8IODl1 CaD such IeUODl produce vegetation 1
".-Subject t What laid of the polar inclination of Mars 1 .Are
bis 8888008, then, like oUNl Why Dot 1 How many &ea8ODS has he 1
Wbat is their leDgth t
a4.-Subject 1 What iI the inclination of Jupiter's axis to the
plane of his orbit 1 How does thia affect hil zones 1 What said of
tbe lun', declination upon Jupiter 1 Of bia temperate zones 1 His
day. and nights 1 Hia poles 1 What is hia light and heat, lUI compared with our globe 1 Hia diameter 1 Ilia r,latiN magnitude 1 Hia
figure 1 The time of hiI rotation upon hil aD 1 Hie mean distaooe
from the lUIll
A.-Subjectl . What ..id of hi. polar inclination 1 What is hiB
IJeriodic time' What iI the ftUtllb6r and kng'. of his ee880DS 1 What
laid of his polar regio081 Where do the ring. of Saturn lie 1 What
is tlle time of their revolutioD 1 How crc.ed by the lUll 1 How are
the aides of the rings alternately enlightened 1 What said of the
1888008 on the sides of tbe ringsl When will they be turD.ed edgewiae towards the earth 1 How will he be enlightened then 1 Where,
ia hia orbit, will he then be 1 Where in seven and a half y8&1'1 after t
227
QUBSTIONS rOB B%AXINATION.
How will hia ri~p then appear 1 What win the sun's decliDatioD
t.hen be from the planet'. equinoctial? What will follow in seven
and a half y8&1'8 more 1 When wW hiB riDga become iuvi8ible? Why
can they not then be Been 1 When will they become visible again 1
Save we any Curtber illuatration of the 8881008 of Saturn, the structure of hiB rings, &c. 7 Have all the planets, then, their da.yand
aight, cold and heat, winter and BUmmer, &C.1
aG.-8ubject 1 What iI celestial longitude 1 [34] When are planconjunction? How illustrated by the map 1 WhAt
planets have two conjunctions 1 What are they called 1 What is
the dift"erence" Illustrate by m!,p. What diiFerence in the diBtance
of Venus from the esrtA at her two conjunctioDs 1 How explained
by the map 1 What conjunction has the e:cterior planetal Why
Dot an inferior conjunction 1 When is a planet said to be in oppo•• tion 1 What .said of the rising and setting of planets in COllj unction
aod opposition 1 Make the astronomical signs for conjunction and
opposition upon the black-board. As VeuUI, passing eastward,
fonDS a conjunction with the sun, how does she usually p888 him 1
How ia this accounted for 1 When does Venus pU8 over the 8un'e
dISC 1 How is euch transit illustrated by the map 1
ets said to be in
av
.-Subject 1 What ia a nderesl revolution of a planet 1 What
.. synodic 1 What is the dift"erence 1 How illustrated by the map 1
How long from one inferior conjunction of VeDus to another 1 Why
do the synodic periods of Jupiter, Satlll1l, &c., vary 80 little from the
periodic time of the earth 1
,
SO.-Subject 1 What di1Ference between the diTect and retrogratk motioDS of planets 1 Can you explain the cause of this seeming
retrogressioD, and illustrate by the map 1
81.-Can you explain the retrogreeaion of the exterior planeta by
the map 1 What ia meant by the " (lTe of retrogradstion 1" Why
have the more distant plane.. the smallest arc?
retmgrading 80 short a distaDee 1
.
Why
80
long in
• a.-Subject ? When ia VenUl etUt, and when tl1en of the aun 1
When is abe morning .taT, and why 1 When e"",ing .tar, 8UJ
why 1 What did the ancients think of this star, and how named l
How long is VentJ8 alternately ~orning and evening start What I:~
meant by her greste8t e/,ongstion eut and west 1 CaD you .lluHtrb.1.0
the diWerent points in th. leIIOD. by the map 1
88.-Subject 1 What is meant by III pAtUe.1" Why do Mercury
and Venus preaent different pbues 1 IUl18trate by map. When dO&t
Ven.. appear largest, and why 1
228
BLBKBKTAllI' .&sTKOlfOIlY.
"'-Subjeet 1 What three factB dOM your aathOl' state reapec&iIIg tbe primary plane." Baye aoy IpObI eyer been seen UpoD
Mercury? By whom? What el8e does be _y he 8BW aod IDe8&lINd 1 What is the teI.copic·t»lor of Mereury" Have you carefally noticed the ten flew. of Ven.. Ihowa on the map 1 What do
you auppoae theee IpObI to be'l What said of the tIIOUnt.ifUI of
VeDU81 What of ber .,..,lne 1 What of her eolor 'I What
doN Fag. 13 on the map repl'Nent'l Where is the obeerver supposed
tD be, and how ••isted in hia vilioa1 Wby would the land appear
bripteet? From what woald th. ohlerver iDfer that our globe revolved
OIl her Oill, and the hnw of her rotation'l From what the inclinatioD
0{ her I1xis" From what mer that abe had an ."".,iere'l W baa
Rid of lODes, colon, &c. " Whicti figures on the map are repreeeatatiooa of Mars? Have Y01l noticed the 88veral figures from 14 to 23,
the views were had, and IDleR? How .. this variety or
appearance accounted for? What said of tbe bright spot, Fig. 221
What Aid of the -.r/cee of MU81 What
Dr. HeISChel of tbiI
planet t Who coostructed a ma, of Man
What is his color 1
\VIaat ia supposed to be the cauae of this roddy appearance" Can
it be discerned by the aaked eye" What said of our knowledge of
the asteroids? Of tbe appelU"lUlC8 of Pallas" Are the asteroids visi·
b1e to the naked eye 1 What i. their t.eleacopic color ? What does
Fir. 24 repreaent 1 What is his color 1 Where are his 1HZ,. 1 What
are they suppoBed to be 1 What is their nUfJlb,r 1 What said of
changes in their forms 1 Of spots in them 1 Is the figure an exact
cBcle" Why not 1
.,.,Juma
-r
".-Subject 1 What does Fig. 25 represent 1 What said of
8aturn's beltll ? IDs ringll ? Of the color of the planet and rings '1
How was Saturn regarded before the invention of the tt'lescope 1
Have you carefu1ly obBerved the diJFerent views at the top of the map
from 1 to 12, and noticed what is said or them in the letIM>n'1 When,
and by whom was the first view had '1 Through how long a period
do these views extend '1 Where have we a correct representation of
Saturn '1 What said of tbe different appearances of Saturn 1 Can
you e~plain the caw, of theee di1Ferent aspects of Saturn, aDd illustrate by the map 1 For what other purpoeee may this diagram be
U8ed'1 What is the fir.t fact shown '1 Dlustrate. What is the
.t:fJlItl point illUltrated 1 How MOwn by map 1 What next doN it
..bow 1 Where are Satom'. .l.ti'ial points 1 His eq.inoctit.&ll
How may this diagram illustrate tl,cliftGtitnN 'I Why can we DOl
lee Saturn in the night at all se880M of the year?
.
.e.-SUbject 1 What iI Satom'. diameter? The distance tiom
the body of the planet to the interior riDg'1 What is the width of this
ring '1 What space between the two rings? What is the width of
the exterior ring '1 The distance acl'088 the enerior ring 1 What.
&he thickne'll of the riDP 1 What doea Fig. 4 reprel8nt 1 What &aid
QUBSTIOIfS POR BlllIINATION.
229
of the stan" What doee Fig. 5 represent'l Describe ita diWerent
part& What does ~ig. 6 represent" What additional particulars are
etated by your author respecting the rotation of Sa~urD, the nature or
hie rings, their actual .paralion, U8e8, &co " What said of spot8 UPOIl
Herschel"
What said of hi8 (ltm0llf'her~ 1 How doee he appear
through a telescope 1 What. his color? What said of Le Verrier"
WhaL does Mr. La.-el say of Le Verrier'. baving ring. an~ a lI(Jt~l·
lit~ 1
«I.-What is the subject of this lesson'l Who discovered Mercury, Venus, Mara, Jupiter, and Saturn 1 Can you tell tDh~n aud by
tDhom the other planets were discovered 1 Who demonstrated the existence of the last Dew planet 1 What otber astronomer was making
.,ilniJar calculations at the ..me time 1 Who first .atD Le Verrie~
and where 1 Can you explain what has been called " Bode'll LinlJ, '
respecting the diataucee of the planl)t t How does the distal)ce of
Le Verrier compare with the distanoes or the fixed etara1 What part
of your book are you DOW in -I What part of the solar eystem have
you DOW. gonl) over or considered t
A.-What .. the .ubject of thUI clGptw 1 What of tbis le.8Oft '/
What are the eectmdaf"J planet. '/ What Dumber is knl)WD to exist "
How are they distributed to the .veral planets 1 Point them out on
the map. In what respect8 do the lI8Condary planets resemble the
primaries 1 What porpoae do they Be8m to answer in the economy
of nature 1 What are they usually caned 1
•••-Subject'l II it probable that Venus bas a satellite 1 What
.. its Buppoeed pniotl, tliBttJftCe, and magnitude?
VO.-Subject 7 Why is our moon an object of great interest to
1181 What i. her mean distance from the earth's centle 1 How long
• she in makin, a aclereal refHJlution 7 A -ynodic revolution 1
What is her hourly motion in her orbit 1 Her mean angular motion
per day 1 Her tlitJraeteT'/ Her angular diameter! Her bulk aa
compared with the em' 'I AJJ compared with the BUn 'I What is
the iacliDation of her orbit to the ~cliptit: 'I The iIIc1ination. of b6r
(I~. to the plane of her orbit? In what time deee she rotate upon
her axis 1 How much light does she reflect, u compared with the
SUD 1
Why doee abe appear u large 88 the sun 1 How does her
diataDCN compare with bia 1 Do you remember in what ratio dvta'f&ce diminishes the apparent lise of bodiee 1 W /&ere and /WW is thil
i"IUltuoated 1
VL-Subject? What doee the apper 'row of figul'8l represent 1
Can you explain the clI. .e of theBe various appearances of the mOOD,
as seeD from the earth 1 How would she appear to a penon stationed in the 8un 1 Explain the different figuroa fl'om A to H. What
~
.
~30
ELBMBNTARY ASTROKOXY.
.,.,giu, .......,....,
are 8Uch a JeVoiatioD aDd the eoD8! queDt chaac- caDed., Wbf'J"8
are the
&ad
in the mOOD'. arbit 1
tIC"'"
Va.-Wbat doea rll. i OIl the map I8p1'M8nt 1 Where are the
moo.. leeR t Where are the jvll mooDS t Which in clJnjunetion, aDd which in OfIlIHititntl [56] How much of the moou is al.
WI1YS eoligbteDed t ~How maay revolutioD8 does the moon make ill a
year 1 What iI a laur yeu t How much shorter is it than the
civil yearl
.U1
What are the ,.u. of a planet'. orbit 1 Are the
moon'. DOd. permanent in the ecliptic t What motion have they 1
To what doe. it amount every IQBar year 1 How long, then, does it
require for bel' nodee to revolve quite around the ecliptic t
Vl.--8abject t
V"-
What iI the .dUFereace between a ade,-etJl and .,.tlil:
revolution of a plaet 1 CaD yoo illUlltrate by any figure on the
mapt
th.
VI.--8ubject 1 What fact respecting the moon is obvious to the
naked eye 1 What fonr conclusions follow from
fact 1 How is
it .hown by the map that if the mOOD always presents the aame side
to the earth, me mU8l revolve on ber uia every 291 days?
VfS.-8ubject t What iI meant by the moon'slibratiou '! What
iI her libratioD in long-it'"" 1 What causes this rolling motion?
What is libration in lGtitu.tk, and how is it accounted for 1
. VV.-Subject 1 What ia the leDgth of the moon'. year? What
laid of ber daya and nights 1 Of the aun'. declination upon her?
Of her 188801181
Va.-Subject 1 What does Fig. 4 repl'8l8Dt 1 What is meaDt
by the " circle 01 illumination 1" What is the termifttJtor? How
does tIlilline travell8 the moon'. diIc t What are Figs. 5 and 6 1
V8.-Subject 1 What particular fact becomes obvious by obIerviDg the mOOD with a teleacope 1 What three circulDBtancea show
the eXistence of 11lJl&r motlDtaiD81 Can you ill_trate by figures 4
and 6 " What is the character of the lunar mount&iDs? Wbat did
Dr. Hencbel 88e 1 What ia said of eeeing cities, fortificatious, &c.,
iu the mOOD °l Hu the mOOD an atmosphere 1 How d08ll sbe bppear through the moBSter teleacope of Lord Roese 1
.
SO.-Subject 1 What ill the average height of the nine ptiueipcd
mouDtains of the moon t Have you looked up TycJw, Kepler, 'Cll&c. 1 Can you point out the principal 8e. upon ber 8W'-
,ern",",
face' .
QUESTIONS FOR EUMIKATION.
231
81.-SubjJct? How many mOOD8 hu Jupiter' ? What are their
diameter. respectively 1 What their dutancell from Jupiter 1 What
thE'ir periodic tirM. 1 What resemblance i. discovered between
Jupiter'. first mOOD and 0Ul'81 What striking contrast 7 How does
its velocity compare with that of our moon 1 How ie tbis rapid motion accounted for 1 How do the orbits of Jupiter's moons lie 1 What
iti their inclination, respectively, to the plane of his equator 1 'Vhat
is said of their eccentricities 1 In what direction do they revolve 1
What said in respect to the visibility of these satellites 1 What of
Jupiter and hil attendants as a whole 1 Can any member of the
class point out each moon upon the map, and (ive their distancea,
.
magnitudes, ~nd periodic times 1
8D.-Subject 1 How many moons has Saturn 1 How is this 88eertwned 1 In what direction do they revolve 1 What Baid of the
jOrm and po8ition of the orbits of the first six 1 What of the seventh 1
Can yon give tbeir dutanceB, respectively, from the body of Saturn 1
CaD any of-them be within the rings of the planet 1 [Compare with
distance LeMOn 66.] What are their periodic times 1 What said
of their relative magnitudes 1 How are the two interior moona ~en
when the rings of Saturn are twned edgewise 1
aa.-Subject 1 How many mooDS has Hel'lChel1 Can you recite their reepective diBtanc81 from their primary 1 What ale their
periodic times 1 What two remarkable peculiaritiel distinguish the
moons of HeI'BCbel1 How ill the latteriDdicated on the map'l WhtLt
is the general form of the orbits of these satellites 1
.,,-SubjeCt 1 Is it probable that Le Verrier hu one or more
satellit.e81 Have any ever been leen, and if 80, by whom 1 What
other circumstances seem to render the existence of IUch mooDS prob8bl~ 1 Do the secondaries rotate upon their respective axee? Hlive
'hey any attendants revolving aroond tlem '/
· 85.-What .. the lubject of this clapter '/
What part of the solar
SY8t~m have you now considered t What is the subject of this lellIlUn? What iI an eclip., 1 A IOlar eclipse 1 A lufUlf'? \Vhore
do we begin in explaining the philOllOphyof eclipaes1 Wbat is a
.hadolD '/ Upon what do the length and form of shadows depend?
Illustrate by map. What would be the form of the earth'8 shadow
if she were larger than the IUD 1 WheD the opaque body is 8f1&aller
than the luminous, how does ita ii.tance affect the I~ngth of ita
shadow? Illustrate by map. What difference betwoen the umbra
and penumbra '/ What, then, is the cau., of a 8Olaf' eclipse 1 illustrate by map. Which limb of the IUD .. first obscured, and why"
Illustrate. What causes lunar 'eclipaesl Explliin, by map. why the
~a8tern limb of the moon ia first obscured. Why a,n, Bolar eclipeee
aJ~ayl at fielD '11WO'n 1 Why luftGr at full .won 1
232
BLEXENTAKY ASTRONOMY.
".-Subject 1 What is the fil'IIt thing to be determined in calculating a eol. eclipee 7 How does the place of the earth in her oraL
affect tbe length of her Ihadow? Illustrate. Why are tbe shadows
of the earth and moon longer at U t and shorter at T 1 Bow does the
MOOn'. position, in her orbit, aiFect Ian- shadow t What is the lAird
circumltance mentioned u affecting the length of the moon'. shadow 1
When the earth • at U. and the moon in pwigee, how far will her
Ihadow extend 1 What will be it. diameter at the earth'. 8urface T
What of the pe""..Jwa 1 When will the eclipee be pcrtitll, and when
tutal? How iI it wheD the lun and mOOD are both Dearest the BUD,
a~ at T and U t How when the IUD and moon are at their "'eGR
dlstancee 1 Why do the IUD and mooD appear to vary in size 1 How
mWlt the IUD and mooD be situated, u to distance. for a central BOJar
eclip86 to be tottJl? How 10111 may a total eclipse of the BUD last 1
When doee the moon appear ",..'l~r than the IUD 1 Should a ceotral
eclipse of the IUD occur then, what would be ita character 'I How
loag may the ring lut in an aDD»lar eclipse 1 What is meant by
" digit. 1" Do you now tlDdentand the cauae of partial, total,
. central, aod aIlR"",," eclipse81 What laid of the eclipses of 185tl,
1861, &0.1 Of thoee of 1854, and 18751 Knowing the time of ODe
eclipee, how CUl we
the time of oth8ll. either put or to come 1
ina
or
• •-Subject 1 What is the ave~ length the earth's shadow T
How doee tbi8 compare with the f'I&OOft. dutaflce 1 What its average
breaatl at the distance of the moon t What three circumstances are
mentioned u afFecting the ezten' and duration of lunar eclipses f
Illustrate the lut-named principle. Why is a lunar eclipse ever
partial? Why are they fUNr G""ul. ? DelCribe the progr•• of
a lunar eclipae.
88.-Wby do we not have two central eclipses ev~ry month 1 DI....
trate. Where must the mOOD be for an eclipse to occur 1 Explain
by }~ir. 2. M118t the mOOD be exactly on the line of her nodes f
What are the 80lar and lunar ecliptic limit. 1 To what do they
amount respectively 1 Bow illustrated by Fig. 2? What singular
motion have the moon'. nodes? Dluatrate. Why are we sure of an
eclipse every one hundred and 88venty-three days 1 What are the
flDd~ montlas ? What the leut, and what the greatest number at
eclipaee per year? What the U8Ual number?
8§.-Subject 1 What caosea the occult.tUm of a .tar 1 What
conc) DOns are drawn from these eelipeee of the 8tarB 1
8O.-Subject t . Do all planets cut ahadoWII? \\l1y canbGt the
primarie8 eclipee each other? What said of tbe character of Jupiter's
Ihadow t Of its positiOD? or the plaDe of his equator' Of the orbits
of three of his mooDl t What said of the fourth, or mORt distant
I&f.ellite' What is generally the cue as to Jup:ter'. moons? Abcnd
QUESTIONS FOR BUXINATIOK.
233
how mallY eclipeea haa Jupiter in a month T Are they u8ually p"".
bal, or tota, and why 1 What ..id of the lbadOWB of hi• •tellites1
What are the immer.um. and man.,.. of his mooD81 How are
these eclipses made IMViceable in navigation 1
•
81.-Subject 1 Bu Satum any eclipeea T Why confined to the
time ..hen bis riDp are 88eD edgewi8e 1 What Rid of Hel8Chol'.
mooDS?
8A.-Wbat .. the IDbject of this eluJptw? Which diviBion of the
book are you DOW in 1 What are the 8ubjeobl of the chapten already
gone over 1 .What is the subject of this fim lealOD on tides T What
are tide.? Flood tide? Bbb tide 1 How many each day 1 What
ca"•• tbe tides T What does Fig. 1 repl'8IIent 1 What does Fig. 2
DIU8tr,te 7 Fig. 3 7 H()w do you account for high tides on the side
of the earth oppoftte the moon 1 IllUlltrate by mRp. What is dIe
8Uppoeed amount of the earth'. perturbation, 88 affected by the moon t
83.-8ubject T Whekre ia the vertex of the tide-wave generally
found 1 How illustrated by mapT What is the cau. of thialagging,
or delay 1 Wby is high-water later and later every day T Why is
everyaltemate tide higher than the iDtennediate ones, when the
DlOOIl iI far from the eqllinootiart Illutrate by the map.
....-Subject" Ie the moon the only caU8e of tid.? What_
the cotnparative bulk of the BUD and mOOD 1 Why, tben, is not the
8UD the priDcipal cause of tides 1 What ia his inftlleJlCe upon tbe
earth, in the production of tidee, u compared with that of the moon?
Would the BUD .loru produce a perceptible tide-wavo 7 When both
iDduencee are united, what is the comparative iaer,... of the tidewave 1 WbeD they ctnlntertJDt each other what is the reeult 1 What
are theee very singular tides called? What the low tides 1 When
do the .,-i'flg tide. occur 1 When the fl,ap ,ide.? . How illustrated
by the map 1 When the 81lD and mOOD are' in oppofttion, bow are
spring tid. produced 1 Doea your author leem latiafted with the
usual explanation of tbis point 1 What objection doee he name 1
What said of ProfealOr Olmsted'. explanation 1 What does Fig. }'
represent 1 What A and C T What Band F T Can Y011 etat8 ProfeaiOr Davies' theory, &Dei WlI8trate by the map T What ..ys your
author of thi8 theory 1
M.-How are our tid. 1dFected by the ."'ance of the mooD?
Illustrate. What principle. iUustrated at E 1 Wi.t .",.itJtion. in
the height of the tidee in different parte of the world, and IunIJ eGa.ll?
Wililt said of Zoea Ct.lu• • detaiDing or butenillg the tides? Of lak.
and inland 118881 Of t.ltmDBplwit: tides 1 Of tides on the aft ?
tNI.-Sobject 1 Define the G";de. of the mOOD'. orbit, and W. .
ill mea. by the II _ _a . , ,/w .,.ular"
IUIIIIraIe.. Ia what ti... iI ea e.tire nmJIaIiaa eompIeted '! 11M
tbiI ...... ea, eaa..-. willa
trat.. by....
~at
_,-.1
"'.-What .. the _bject 01 tbia ella,..., What aN the aubjeeta
of the chapte.. preeedinr t What .. the 811bject of lb. luatna., What
..w of the C_lJeter of comeI8 t FrGID what .. their .... derived 7
Of what "..u do cc.ne........., COT • r 1 De.cn"be each. Have aU
cometa a alleleu1 Bave they all tail.., What _yw C...Di of the
comet 0( 16821 What. the pDeIaIllireea.. of the tails of eometa"
DIWltrate. What peculiarity in the comet of 1823, and hoW' iU __
lrated by map? Row are the tail of cometa ...."y clUTed 1 What
• the c:tI.. of th. clllftblre" Coakl a comet get through oar atlDOIIpbere ., u 10 .trike the earth? What aid 01 the comet of 1744 t
How "'OWll OD the map 1 What.aid of the eltnt,..tio. and eotdnIe,in of the tail. of comet. t or ••
expe-iOllS? or the pA,neal
of comet. 1 What ",...1. of their ligbta. . 110m attnctioD 1
Wbat W88 Sir l.laac Newton's opinion of their de_ty? Bow are
their .,.6iu 80IJletimM a8Bcted by the attnctioo of the plane.. ! Are
.t.r,
tl_
they .,If·lumillOU8, CJI' opaque bodie.1 What proof1
reality U pr, bodies 1"
Are the, iD
88.-aobject81 What aid of the comparative ••e of the teaeki of comets 1 CaD yoo give the diameter of any 1 What said of
the magllitude of the tait. of cometll1 Of that or 371 yeam before
Chriat 1 Of A. D. 16181 Of 1680 1 Can you point out theee
comMa on the map 1 Give the length or the taiIa of lOme of the moat
remarkable cometL Doe. the angular length or comets, as I88D
from tbe earth, Ibow their true relative length 1 What said of the
_locity of comet81 What ioequalitiee 1 When ia thei!' yelocitv
6'"sate.t 1 When le.., '! W bat . u tbe anplar velocity of
COIDet 01 14721 [&8 leMOn 10, and map.] What wu the ADurl,
'Delocityof the comet of 1680 1 What laid of the ,naper.'ure of
comets wbeD neaJ'Mt the 8un 7 What wu the perihelion diataDCE' of
tbat of 16801 What its relative light 1 Ita "eall What IAlPpoaitiOD respeCtiD, the prodsctitHa of the tails of come. 1
the
".-Subjecbl? What. the p~du: titJU of Bncke'. comet 1
Of Bie14'.l Of Balky'.? Of tbe comet of 1680 T When next to
return 1 Ha ve any lltill longer periods 1 Do all comet. I'8tum to our
ayltem 1 Wby not 1 What ill ProfeMOr Nichol'. opinion 1 Who
COBcun witb him 1 What said or the GvtllftCe to which BOrne that retUfn must go 7 What does this prove in rerud to the distance to tbe
rixed atars 7 What aid of the periA.elion avtGnce of comets 1 How
were tbe perihelion points of the ODe hundred and thirtY-lElven comet.
mentioned distributed? Wbat said of the ftumb,.,. of comets 7 What
circumltal)c~. render it probable that their Dumber amounts to millioua7
What wu Prof~r Arago'. coBcluaion, and from what premia. 7
QUBSTIONS FOR BX• •INATION.
235
lOG.-What said of the direction of comets? What _Y8 ProfetBOr Kendall of their inclination.. 1 How is this circomstance re·'
garded by him 1 What is the usual form of the comets' orbits 1 Why
Dot eeen 10llKer from the earth 1 How were comets formerly regarded 1
Are. they dangwoa in the solar system? Is a collision with the
earth probable 1 What are the chance, for 8uch a catastrophe 1
What would be the result, if they should strike our globe 1 What i8
Profeaaor Olmsted'. opinion 1
101.-0f what does this chapter treat 1 What is the subject of
this particular le'Mm 1 What said of the po,ition, office, and coml(lf"ative importance of the 80n 1 What is his dia~ter? How
llloatrated by tunnel, and railtDtJy 1 How does hi8 diameter compare
with that of the earth 1 How hi.
1 How with the whole solar
tyatem be8idee? How is the suhject of his magnitude iJlostrated by
reference to the moon's orbit 1 What is tho true form or figure of the
.un 1 Illustrate his relative diameter by the map.
ma.,
,
10Sl.-Sobject' What does the telescope reveal opon the sun'.
disc 1 What aa.id of their number 1 Are spots always visible 1 What
is the greatest nomber ever visible 1 What aay. your author of hw
own observations 1
lOa.-Subject 1 What is the appearance of the solar spots t
Point out a ftucleu" and its penumbra, on the map. Can you name
some of the principal phenomena of the solar spots 7 What did
Proffl88Or Henry ascertain 1 What was Lalande's opillion 1 What
thooght Dr. Hel'llChel of this soggestion 1 What W88 Herachel'.
opinion 1 What said of tides on the SUD 1 To what conclusion did
Profe880r Wilson arrive 1
lCK.-Subject 1 What view of the 80n is shown on the map 1
W"at 8aid of Dr. Hel8Che)'s ,observations and statements 1 or Dr.
Dick's views1 What does he infer from the fact that spots have
been seen by the naked eye 1 What says yoor author of this conclll8ioD 1
loa.-Sobject 1 What is the inclination of the sun's axis to the
ecliptic 1 What proof have we of his revolution on his axis? Iu
what direction does he revolve 1 In what tifM? What ddFeren~e
hetween his tidereal aDd .ynotlic revolotioua1 How do yoo account
for this difference of time ?
lANI.-Subject 1 In what direction do the solar .pots CI'Oll8 the
.un". d~1 How, then, can he revolve from west to east 1 How
illustrated by two 8pher~1 What said of the appareut inequality of
motion of the solar spots 1. How explained, or accounted for 1 liow'
~U8trated by Fig. 11 Explain their change of figu.re by the m<.Lp.
286
BLEMENT.RY ASTRONOMY.
What chaDges in the apparent dir~ction of the spots at difFerent
8eUOD8, and how explained' and illustrated by the map 1
IOF.-Subject 1
II this subject well understood 1 How does the
IUn appear through a teleeeope 1 What was La Place's opinion con.
cerning it 1 What is the most probable opinion 1 What says Dr
Herachel of the tmapw"ture of the sun 1 What calculation in reference to tbe light and heat of the sun'. 8Urface 1 What remark in
regard to ignited solids '1 What does Dr. HeJ'BCbel infer from this.,
DOes hia conclusion ftece ••arily follow 1 What says he of a rejlecti'De
caRtJpy, &C. 1 What does he consider the great mystery in regard to
the- lun 1 Does chemical ltCience throw any light upon this question T
What d068 Dr. Hel'llChel conjecture 1
loe.-Subject'1 What is meant by the soditJcal light? What
is ita fM'fll? How does it Beem to surround the 8un 1 With what
does ita shape 166m to ,correspond? How, then, do we account for
its apparent 8hape as seen from the earth 1 What said of the Rature
of this 80bstance 1 What is Profe&l!JOr Nichol's opinion 1 What says
Dr. Herschel? What say Dr. Dick and La ,Place upon t.his point 1
Wbat are the tlimennOft. of this phenomenon, 88 given by Dr. HerIChel? What other opiuion is advanced respecting the zodiacal light 1
What -y" ProfeB»r Olmsted 1 Wbo concur with him ill this opinion? Which are the best months for observing this phenomenon 1
What interesting fact is stated by Profel8Or Nichol? What does this
...eem to indicate 1
IOD.-Subject" What astonishing fact bas been ascertained
respecting the lun' How many motions haa he 7 What is the fir.t ?
The .econtll The tlaird? Who aacertained the direr-tiD" and
"elocity of the 8Dn 1 What i. the point of tendency? What is the
estimated "elocity of the BUn? With this tact in view, how Mould
the sun be regardE'd? What still more magnificent idea 1 What
further ligbt is thrown upon this intereSting subject 1 Who haa the
credit of discovering the "emtral sun 1" Where does he locat.. the
centre of our cluster of 8uns1 What star does he fix upon as the
central orb 1 What is the 8Upposed distance of Alcyone, as compared with that of our sun" }Jow does this distance compare with
t4at of Le Verrier 1 How long would light be in travendng this distance" What is Mldler's estimate of the periodic tirM of the Bun 1
Of hj. ",loeity ? How does the plane of the aun's orbit lie, with
ret'pect to the ecliptic 1 Where the tUCeatling notk of bis orbit 1
,110.-What i. the subject of this cluJpter? Of tbis particular
le880D 7 Can you deecribe what is cal16d the nebular theory? Wbo
originated this theory? What circumstances seem tG f ••or it " I.
it open to allY BeriODS objections" What ill the fir.t? What is the
.eetmtl objection T The tlard? The fourtA ? The fifth? Do an1
QUBSTJOlfS FO& BUXm.TION.
287
reran! this theory incoJUJiateDt with the MONic account of oreatioa t
What is the opinion of your author 1
111.-Subject? How many priDcipallaw8 that govern pJauetary
motions 1 What called, and wby? What is thejir8t of these laws 1
What is an ellip,e 1 What is meant by the f1UJjor, or tranlmer.e azu
of an ellipse 1 What are the foci 1 What i8 the radiu.8·."ector 1
[See map 7, Fig. 1.] What is the ,econtllaw of Kepler? CaD Y011
illustrate this law by the map 1 What i8 the tAird law 1 CaD YOIl
illustrate by an example 1 Does thia law prevail throughout the solar
Iystem?
llA.-Subject 1 In thi8 iIIustratiou, what i8 tile relatJve diameter
given to the SUD? Mercury 1 VeDU81 Earth 1 Mars? The Asteroids 1 Jupiter? Saturn 1 Herschel? Can you give any of the
d"ttlRCe, accoq to thia repl'e88Dtation 1
113.-What
MI,-
ill the qoestion discu.ed in thw lesso11 1 What
picio1& was entertained before the discovery of the asteroids? UpoD
wbat was it bued 1 What influence had this opinion upon astronomen? What opinion hu been advanced in respect to the origin of
the asteroids 1 What aix facta are 8Upposed to favor this hypotbeaia1
To whom does this theory belong 1 What other astronomers favor, it 'I
What say. Dr. Henchel of it 1 What remark by Dr. Dick 1 What
Dew theory by General Root 1 What doea your author think of Dr.
Olber'. theoryt and why 1
U"-What question ill discosaed in this chapter 1 Have we any
direct testimony upon thi8 subject 1 Upon what, then, is the argument based 1 What is requisite to a foil appreciation of this argument
from analogy 1 What facta, then, seem to require that the planets
should be inhabited 1 The first ? ' Second 1 Third 1 Fourth 1 Fifth 1
Sixth? Seventh 1 Eighth 1 Ninth 1 What argument from the animal inbabit8dneas of aU parts of our globe 1 What part of the universe, and of your book, have you now gone over? What yet
.remaiDS to be coDBiderecl1 What.. meant by the BOlar 8y,tem 1
What by the .tkrealleaNU 1
UI.-What is the subject of Part II.? Of this first cAa.pttr?
or this particular IMIOn 1 'Vbat four characteristics are mentioned
as distinglliabing the fixed atarB 1
118.-What i8 the ftrIt step in cl8llifying the stars 1 What the
.eoad1 How many magnitudee1 Whioh are visible to the llakt'ld
eye, and which telescopic 1 Illustrate by map. Does this cJaaI.fi·
cation indicate their tlctutJl relative magnitudes? Why not 'l What
is the third step in clusifying the stars 1 How are the individual
IWB in each coD8tenation desipated 1 What is the fourth help in
238
KLEMBNTA.D. Y A.STRONOMY.
finding and Dumbering atan1 The )ifth1 Can you give lb.
"allie' of any stara T Can you Dame any cl..tw.l How are the
.tare still further diatinguiabed T
or
11V.-Subject T II it poable to determine the actual number
the fixed starsT What is the estimated number visible to the naked
eye 1 Can you give the numbers of each of the first 8ix magnitudes 1
What is the estimated number visible through telescopes 1 Cau you
recite the number of eu.h magnitude from the seventh to th6 twelfth
iuclu8ive 1 What is the entire number of all magnitudes 1 What
remark of Dr. HeJ'8Chel1 Of ProfealOr Olmsted 1 Wbat estimate
respecting the Dumber ot worlds in our firmament T How do all these
compare with tbe bouDdleaa univel'88? What idea is advanced in
regard to the employment. of the Chriltiau in a futore atate 1
ll8.-8ubject 1 What is the estimated tliBttJRCt of the Dearest
fixed star! How lon, would light be traversing .ocb an aby.. 'l
How many timea its prNent di8taJlce must such a 8tar be removed to
appear only of the twelfth magnitude 1 What astonishing coDclusioDiJ
follow from theee premi8e81
.
l18.-Subject 1 What inference respecting their magnitutk.
rrom their duttJ1ICe, 1 II it probable that the atal"8 are of uniform
lize 1 What opinion prevails among utronomen respecting them 'I
How many timee his present distance must our 8un be removed to
trall8lDit DO stronger light than Sirius 1 How far oir would that be 'I
How much I. . than the distance of Sirius1 If, then, the light 01
Sirius would equal that of our 8UD, though seven millions of miles
farther off, what must be his relative magnitude and splendor 1 What
does Dr. Wollaston conclude respecting this &tar 1 What is the magnitude of V~ga in the Lyre, 88 compared with the 8UD -1 Of 61 in
the Swan 1 What inte.reatiDc circllrnehtnce ja mentioned reepectinK
Sir John HeJllChel and Sirius1 Can)'oo give the relative li,ht ol
the stan of the 1iDt six maanitudee 1
lAO.-Subject 1. What are coD8tellatioD8, and what was their
origift 1 What said of their tJfttiquity 1 What proof 1 What aaid
of their ft"mI(.n at fibIt 1 b there room Cor any additional conateUatloDS1 How are the coDStellatioD8 divided, or claasified 1 Which are
the *odiacal? Which the nortAttn? Which the _uthem 1 What
other dietiDction of the constellations? Can you name the .odiGcal
con8tellations 'I What is their number 1 How many ftfWtAeTft conatellatioQ.e are there 1 Of theile, how many are modem 1 Can you
name any of the northern constellations 1 What is the number of
.utluna constellations 1 How many aDcient 1 Modem? Can YOQ
~ame some of the southern oouatel1atioDs1 Can you recapitulate the
number of coD8tel1atiou8 in each divi8ion, and the total DIlIDber-r
What is the total Dumber of priDcipal .tara 1 [Thls nu.mber itt 1917
QUESTIONS POR BXAlIIIfATION.
239
1e811 tban the· number given u visible to the Daked "ye, in the table
117; bot one table includee only the "principal" starJ, while the
other embracee all that are " tMibk."]
, A1,-Subject 1 Upon what ael. is the student to trace the
constellationa? How are the zodiacal coD8tellations arraoged 1 How
may A1V• .,. known 1 How find Tau"" 1 What &aid of the largest Btar in this coustellation 1 What are the H !lade8 ? Of du.--ir
arrangement 1 How may' 08'lnini be known 1 What said of Cancer 1 For what distinruiahed 1 For what is Leo remarkable 1 Wha t
iI the -.flle, magnitude, and p08ition of bis largelt star 1 In whl1t
manner are his other lItal'll arranged, and where, ill tbis arrangemeot,
is Regulus 7 What other aar i. named, and what itJ ita magnitude aud
position 1 Deecribe the next constellatioo. What star is named, where
is it round, and what ita magnitude 1 What said of the remaining
atara 1, How may Lilw. be known 1 What constitute the beam
of the ecales 1 Where is the 8mallest ot the four 8tars 1 What said
of 8ctWpio? Of his head 7 Of his relation to the ecliptic 1 What
star is Damed, and what laid of its poaition, color, lind magnitude 1
Where does Oapricorn.. lie, and how may it be k llown 1 How i8
Aquariua represented t What are the magnjtudea of hiH fOllr largest
at&l'8 7 How find the le.d of the figure 1 DeflCribe PiSCN, their
position, number of 1tarB, &c. Whe~ is the largest star situated, and
what is ita fUJme and 1IUJgflitutk ?
•
•
UA.-Subject 7 Where do we begin this review, and in what
dir6ction do we proceed 7 How may Andromeda be known" Describe the figure. What said of the middle star 1 Of the one ",Nt
of Mirach 1 Of the e.'~m one 1 What aaid of the position of
Mirach in respect to the CoiOles? What of the Bize of the three
principal atan 1 Of the girdle of Andromeda 1 What directly Boutb
of Mirach 1 Where is Per-,eu lituated? Wbat is the figure" Where
is Algol situated, and what is ita magnitude 1 What star eut of
AJgol, and how far 1 What other Itam are mentioned 1 What i8 the
figure of Au.riga, his posture, and position 1 What said of his principal &tar 1 Where situated, and how known 1 ,\\'here i8 the L:Ju
•• tuated, and what said of ita component stan 1 Of what is Leo
Minor composed, and where sitaated 1 What said of CO'11&G Berellice', its situation, and principal star? What of Charles's Heart 1
What is the figure of Bootee 1 What 18!P star in thi8 cODBtellatioll,
bts magnitude, IituatioD, and oolor 1 What 8aid of his "IOUS 1"
What other principal 8tar8 in Bootes1 Where is The Crown situated 1 or what doe8 it 00D8iat 1 What ill the poeition, rDllgnitude,
and name of the largeet aar 1 How elae known 1 Where i8 Herculee situated 1 What the figure? How placed? Describe tb is
constellation. Where i8 OpkiucAu, situated 1 D~8Cri~ the figUl e.
What constitute the Mad of the serpent 1 How trace the folds of the
I8rpent 1 What ia the ume auld mag'I.itaM, of the P!·.uc!pal IJtar Ie
,
240
BLEKBKTABY ASTBONOKT.
th. conatenatioD 1 Where is it BitoaW 1 For what ie Aq'J.iltl
eonapicU0U81 What ia the
po.tion, flltJgnitutl~, and appelJr.nee of ita prineip~ star 1 Where, with respect &0 the Eagle, dOO8
the conetellidion A.tinou8 lie 1 Where is the Dolplin aituated,
and bow may he be known 1 How is Peguue situated, and
how dNCribed 1 How may he be known 1 What said of their
magnitudes, &e.1 Where ill the Hor.'. Head .tuated, and boW'
deacribed 1
What CoDltellatiolUJ are Den to be coll8idered 1 Where is Ursa
JliftIW aituated 1 Of what doee it coD8iat 1 In what form are til"
.V~D prillcipal .tan arranpd, and where is the Pole Star 1 How
lDay UrM ltIfJjor be known1 How many.ara in the Dipper 1 What
part of the Bear do they conatitute 1 Can you Dame any of these
8tara 1 For what is Jli.ar remarkable 1 Which are tbe Pointl!r8,
and why 80 callE'd 1 Where doee the le"d of the Great Bear lie,
and of what compoeed 1 What aid of hill feet' What said of the
.zteftt and 8itutltion of Draco 1 How may he be traced 1 By what
may hie "'~tltl be identified 1 W-hat ill the magnitude of hi. principal
Ital'lll Where does CepAeu lie 1
he any coaspicuous stars 1
Deecribe the figure. How is CtUriopritJ repreaented, and how situated 1 Of what ia ber eluJir compoeed, and what are their magnitudes 1
For what is Lyra distinguitlhed 1 Where lituated 1 What is ita principal star called '1 What. ita magnitude" What other atara in this
constellation 1 Where iI Cyg"," situated 1 Deacribe ita princip.1
atara. Give the ntlme, place, and magnitude of the largest oi the
group. What said of the remaining stars 1 Where is CameloptJrdalra
.tuated 1 What 8aid of its chllracter 1 or ita principal 8tars 1
Where is ita h~(Jd situated 1 or what is the Lynz. composed '1
Where situated 1 I ts three largest stars are how large 1
ft""",
au
U3.-Subject 1 What general remark respecting the southern
What is the comparative magnitude of Cetru 1
Where' situated 1 How placed 1 How may hi' Matl be known '1
Give the name, place, and magnitude or hie lalJest star. Where is
Orion, and what said of bim 1 What i. the figure 1 How many
principal stara 1 What stan form the ahoultler.? The IuJatl ? The
6elt or "bands 1" What other Dame have they, and why 1 What
cOll8titutes his tnDortl '/ What are the belt and sword together 8Om6times called '1 Which star is called Mintiktl, and near what is it
situated '1 Where is Rigel, and what his magnitude 1 Saip", and
his magnitude 1 Where may upru be fouod, and bow know u '1
What is t.he DaDle and magnitude of his principal star 1 Wllere does
. the Do". liel How many visible &tara 1 Name the brightest, and
Dext brightest, and give their relative positions. How may Bet. be
IlDOWD 1 What i. tbe direction of Eritlanu? Its Jellgth 1 How
dividAd 1 Where doee the southern begin and tennlllate 1 ['rhe
"utAern stream is a continuation of the northern, which forlDs a bt1ud
Dear Cetus. alld puaee off lOutheMteri7 towards the Dove, and \beD
consteUatiolls 1
QUES110NS FOR EXAMINATION.
80Wl
to the lOuthwest till it dieappean.
241
Rigel,. in Orioo, is in thiI
ItreWD. Its remaining stars are mostly of the third magnitude.J
Where is Cani, Major situated 1 How, fouod? What said of
8iriUIJ 'I Where may Can;" Minor be found 1 What principal &tara,
their narnes, and. magnitudes 1 Where is The Unicorn located 1
What is the magnitude of his principal stars 1 How may his head' be
found 1 Where may the head of Hydra be found, and how known 1
What star in his heart, his position, and magnitude 1 Where is Th.
OrolD situated, and how repre8(llnted 1 What number of visible atan,
and th~jr magnitudes? What said of .Argo N a,,;" 'I How situated 1
- How known 1 Where is the star Mflrkeb 'I ,What atars of the second magnitude 1 What of the first 1 What said of CentaurU8 'I Of
Lupru'l Where is 8e~taRl'l What is the size of its larpst star,
and how situated 1 What laid of TIuJ Or088'1 Ita situation, aDd
componena stars 1
i8 the subject of tbis cAapter 1· or thi8 le,1IOft 1
What meant by double, triple, and multiple stars1 What other
Damell for the lame things 1 In what two ways are stars auppoaed
to be rendered double 1 Are these companionabips more frequeni
than could result from accidental causes? What does Fig. B reprellent 1 What said of their color and m.itudea 1 Why an interest·
illg double star 1 What does Fig. C repreEM\nt 1 What said of the
color8 and magnitude8 of its component sta1'8 '1, What is their dllttance from each other 1 What does Fig. D represent 1 Their magnitudes 1 Distance apart 1 Their color. 'I What said of this Btar ~
a te8t object 'I Of what is Fig. E a representation 1 What is the
color of these stare 1 What their magnitudes, and distance asunder 1
What estimates have been made of the number of double sttr.lB1
What first led asirGnomers to 8UBpect the physical connection of
double stars, and their periodical revolution 1
- JJI4.-What
UI.-Subject 1 What are Binary 8'!J8tt'fM 'I How were their
revolutions detected 1 What &aid of the periods of thOle best known 7
What double star is mentioned, and where found 1 When first noticed 1 What is their periodic time 1 Their angular motion 1 What
curious calculation has Dr. Dick respecting these stars 1 What system is represented at Fig.- G 1 What is its probable period 1 What
does Fig. H represent 1 Can you give their period, color, and mag"ituae, 'I In what light should these systems be regarded 1 What
eays Dr. Dick-of them 1 What said of their proper motions in space.?
What is the supposed cauae of the variety of colol'l they present 1 II
it probable that the 00101'1 are merely Complementary in all casea 1
What said of isolated red st&r81
are
1A8.-Subject 1 What
"ariable 8tara'l What ia the caaraCler of their variation 1 How is the term " period" applied to variable
atara'l What two relDarkable periodic stars are mentioned 1 Where
,
242
•
aLBXBKT.BY ASTBONOMY •
is .ir. lituated 1 What laid of its variatioD81 Where is Alpl'
What laid of ita variatioDl1 period, color, &c. 1 What is the suppoaed
• .,. of these periodic variatioDs1 Wbat _ys Professor Olmsted 1
What other theories to account for these variations '1 What remarb
by Mr. Abbott"
UV.-Subject 1 What are tmaptWary .tGr. 1 What aid of
Hipparchua'l
What of the temporary star of 3891
Of that of
Nuvember, 15711 What remark by Mr•. 8umufJilie 1 What
obaervation by Dr. Diele 1 What opinion by Prole.sOT Vinee?
What ~ay La PlGce, and Dr. Goode 1
",,-Subject 1 What Rid of introducing tbis subject here 1
What are the falling or shooting stan1 When great DUlnoom fall,
what are they called 1 When did &Il.e most remarkable of theae
occur, and bow deecribed 1 From whence are theee meteors 8Up~ed
to come, and how ignited 1 How does Profeaaor Olmsted account 10r
them 1
lAIt.-Subject 1 Give the ftt.lfM. and "lGce, of some o( the
For what sometlmes mistaken 1 What list haa been
formed, and what said of." Now known to be cluteT8, and uot
t:OfMul Wbat said of the ffJ't"'fM of tbeee clustem1 What said of
the Bomber of Btar8 tbey cootain 1 What said of Fig. I, and of red
ItaJ'II q What aid of the probable nature and tl;'tance, of tbe indl'Vidual atara of theee clusters 1 What does tbelr globular figure indIcate 1 What fwther aaid of J and K 1 Of a new cluster 1
cJ.Q8te1'8.
1IO.-Subject 1 To what is the term MbuldJ applied 1 What
are re.l"tJble nebulm1 What ifTeaol"able 1 18 it likely that any
DeboIe are actually irreeolvable 1 \yhat evidence from Lord Ra.e'8
observatioD81 Where is the newly discovered .piral nebula situated 1
What resemblance to our Milky Way 1 What does this nebula reI18mble 1 Is this, too, composed of illdividual stars 1 Describe Fig.
L on -the map. What said of 8inglt and double nebulm 1 What
epecimen given, and where found 1 What specimen of hoUow 'nebu~,
and wbel'l found 1 Wbat are ,tellsr fU!bul~ 1 What specimens, aDd
where found 1 What laid of the 8un and .odiacal light? Whlit
are plt.lnett.lry nebultB 1 What said of their magnitude ? What
1I1ustrative specimen 1 What tLl"e annular nebulre ~ [8ee annul..,
in the Appendix.] Where may the most conspicuous be found, and
how described 1 What d061 Fig. R represent 1 Fig. S 1 What does
}'ig. T represent 1 What said of the nU1nber of nebuJm? What
is ".tar dU8t 1" IIIUltrate appearance by the map. What iIlusUa. tion of the UBe8 aDd powem of ibe telescope from this map 1 What
is the object of tbis experiment 1 What says Sir John Herschel of
the uebule 1 What said ot the Milley Wt.ly 1 How iIIW1trated by
map 1 Why, theu, appear 1M) extended 1 How would it Ilppear'to
J
.
•
243
QUESTIONS FOR EUMIN A.TION •
an oMerver II far off 88 the nebub., in the Lyre 1 1\la1, thereCore
be called what 1 What is Madier's conclusion in respect to the
structure of our stellar firmament 1 What estimate by Sir W. Rep.
schel relative to -the numbw of the fixed stars 1 What said of then
probable mutual distance" positions, and offices 1 What idea of the
enent of the univerae drawn from the dimensions of our own cluster.
and the number of clusters in remote regions? What closing re1leotioDs are subjoined by your author 1
•
•
/
•
.s ••.
HUNTINGTON AND SAVAGE,
RL 8'1'8111ft', . ."" 'W'OBK,
PUBLIIU TilE POLLOWDIG
'-.~LUABLE
SCHOOL BOOKS.
To which they very relpectfull, solicit the attention of County and 1'ownl
IlupenoLenuents, Trulleel, School CommiUeel, Teacbera, and others in1.e.roMed in the cause of edu.catioD.
.
. AN ELEMENTARY ASTRONOMY.
'lor Academies and Scbools. Illustrated by numerous original oolonMl
dlagralos. Adapted to uee witb or witbout the author's Large Mal&
By R. MA TTI80N.
Fifth Edition, with QuestioDa and a Glosnry.
This is one of the moet comprebensive and splendidly illustrated wora
OIl Astronomr that has ever been published in the United States. Its plan iI
eminently onginal and philosophical. It il collfined to the fACt. of the act.
ence, or the res.ltB that have been reached during the lapse of ages, Ytithou&
delineating ita Mythologi(~al history. or tracing tile processes by whicb theae
facti have been 8scertAlnp.d, either by tbe use of instruments, or by mathematical calculatioDtl. It embodies all the late discoveries, and is equally
adapted to private Jearners. the library, and the schoolroom. 88 it is complete in itself, independent of the large charta. As a book of reference it it
iDvaluable. To this may be added its perfect adaptation to use Mlit/a the larre
Mapa, (of whicb the illustrations in the book are exact copies in miniature,)
., that tbe learner baving the Maps. baa on a large scale the same dia~
by which to illustrate the lesson at the recit.at.ion. that bave been preViously
Itudied by the pupil in the text-book. To say nothing of the recommeJlda.
tions that follow. the sale of ta tA"..aJId copies of this work, in a little OV8f a
,.,., iI a sufficient proof of ita popularity and intrinsic value.
ASTRONOMICAL MAPS,
~pted to
ulle with the " ELBIIEICT Aa y ASTao.oIlY." and de~igned to jl1ue&rate the Mechanism of the Heavens. For the use of Public Lecture...
Pri vate Learners, Academies, and Schooll.
By H. M.TTISON.
This series eonsista of Sixteen Maps, or Celestial Charts. eflch 38 by oM
IDches, representing the various appearances of the Heaven]y Bodies-th.
Bun, Moon, Planets, Cometa, and Fixed Stars-and illustrating the lawe
which govers them in their motions, the philosophy of Tides, Eclipses, and
Transits, and indeed all the most interesting and wonderful phenomena of
&he Mechanism of the Heavens. 1'be sixteen Maps cover an area of nearly
100 8Qwne feet. They are printed upon a black ground, answering to the
Ilatural appearance of the heavens io the night, and are beautifully colored
and mounted upon slats and rollers. They are beyond comparison the m08&
Iplendid and complete eeries of scientific charts ever published in this couotry. They are not only invaluable for Seminarie., Academies, and the higher
inltitutions of learning, but at the same time are admirably adapted to popular use in Common Schools. 0... tAouarul .d8 of this work have already
been IOld and gone into use in different parts of the country; and the unaDimity and cordiality with which they are commended by aIL who have us~
or examined them, i6 truly graufying to the publishers. (See fo~owing page.)
MAPS, per set, in case, with cloth backl, •.....•.................. $20 00
on 8trong papel, without cloth backs.
15 00
Books per copy J • •••••••••• • ••••• ••••• • • •••• •• ••• • •• •••• •• ••• • • • ••• • • • •
50
"
U
"
~ Each Set of Maps is nicely packed in a Wooden Case, lind can be
I8Ilt La order wi~h perfect safety to any pan of the Unlt.ed States or Canada
,
------------------------------------------------The attention of
8upm"tend~"t,· of
T.fJcl&er., U
re~ctf'ldly
8clwoZ"
Tru.tt•••, tJtttI
i"mt,4 to IAe /ollOfJlifw
RECOMMENDATIONS
Of the .. Blementary Astronomyt" and
Mapa."
II
MtroDOmleal
Having examined, aDd aeveral of 1J8 UIed, the EUDNTAlty A...
and AITa.ONOJlICAL ~AP8, by H. Mattieon, we are prepared
to say, that in Olll opinion, they are better adapted to the purpoeee
of ~Iementary ill8truction in Astronomy, than any other work or apparatus now before the public. We would therefore cordially recommend their introduction into all schools where this sublime lIlieuoe
ia taught.
TRONOMY
EDWARD COOPER Sec'y of Teachers' A88OCiatioD, state N. Y.
ALBERT D. WRlGH'!:, Principal Normal !nst., Brooklyn, N. Y.
lAS. L. McELLIGOTT, Prine Col. Scboc:!!t N. Y. city.
JAS. R. BOYD, Prine Jefferson co. Inst., watertown, N. Y.
R. K. SANFORDt...Teacher Natural Science, Middlebul'J AcadelDJ.
Wyoming, N. Y.
N. BRITTAN, l'rincipal of Union School, LY~DI. N. Y.
R. F. HICKS, County Supt., Livingston co., N. Y.
ALONZO BEEBE, County Supt., Ontario co., N. Y.
HENRY GILLAM, former teacher of Math. Cayuga A.cademy, N. Y
B. R. McALPINE, Supt. of Public School!t RoChester, N. Y.
ELLERY S. TREAT, Prine .Pub. School .1"140. 1, Rocbester, N. Y.
WM. BARNES,
"
"
,. 6,
"
A. F. HALL
" u " 7,
"
REUBEN JOHNSON, U
"
"I,
"
DANIEL HALLOCK, ..
."
"11,
"
A.. 8. GREGORY,
"
"
"14
"
H. G~ WINSLOW, Prin. Union School, Mount MOrril, N. Y.
8. P. BARKER. Prine Public School No. 10, Brookport, N. Y.
G. L. FARNA~) Prine Public School No.3, Watertown, N. Y.
G. R. JACKSO.N, Teacher, Oswego, N. Y.
1. PATTERSON. Prine Public Scllool No.4, N. Y. city.
JULIA B. CLARKE. Teacher of Public School No.1, Oswe,o, N. Y.
Prom Plto.. Ml'I'OlIJ:L, Dir,ctor of tie Citu:tftfUJti OHerN,.,.,.
In a note to the publishers, Prot: M. saye:
" Your series of Maps are hung up in the public reception-room of
the observatory. I am much pleased with your plan 01 speaking to
tile ey~; aud am confident that these maps will lOOn fiad their wal
iP..o every well-conducted schooL"
--
16
THE
GEOGRAPHY OF THE HEAVEN&
AND CLASS-BOOI[ OP ASTRONOMY.
I wL 18mo.
~mpaDiecl
by • CeleRial AUu, imperlal4to., aeady colored.
. . admirable work to follow the" BL.M.wTAa., AI,.aOllOMY" AIID .. .&.
"aONOMIO.a.L M.a.,•." The two works together preaent a more thoroua
embodiment of the leienee than any othel'8 of the lame compus, in die
country.
COXT.WTS 0,. TRW ATLAI.
1. Plan exhibitiq the relative Magnitudes, Distances, aDd Position of tbe
. different Bodies which compose the Solar SY8tem.
I. The Visible Heavenl in January, February. and March.
a. The Visible HeaveDs io October. November, and December.
4. The VIsible Heavens in July, August, and September.
O. The Visible Heavenl in April, MIlY. and June.
I. The Visible Heavenl in the South Polar Regions, for each montb ta
the year.
T. The Visible HeaveDl in the North Polar Regions, for each month ill
the year.
L PlaniBphere of the Whole Heavena, on Mercator'e Projection.
B., E. A. BURRITT. A. K.
With .... Introduction by THOIU.. DICK, LL. D., Author of the "ehri.tum
.
Philoaopher," written expre181y for this work.
A .-ariety of interesting facti and obllervationa, embracing the latest im..
provements in tbe science, were derived directly from the French and EDJ..
lish Observatories, ,..,••Z, for this Clas•• Book1 and are not contained m
an! other. It is now comin8 generally into use In our principal SemInaries,
ana' il recommended to schools in general by membeJ'l of the Board of Examination of Yalp College, as a work more needed, and which, it is believed, will be more useful than any other introduced into our " Instituti0D8
of Learning, for a number of years."
This book, as its title importa, is deligned to be to the starry beaveu
what geography is to the earth. Such a Clase-Boolt hae looe' been needed.
Hitherto, the science of the stars has been but very superfiCially st_died in
our schools, for want of proper helps. They have conunued to gaze upon
the visible heavens without comprehending what they saw. They have
C8!i1t a vacant ere uP.t!n the splendid pagel of that vast volume which the
Bight unfolds. as ('hlldren amuse themselves with a book which they lU'8
unable to read. They have caught, here and thero. as it were, a capital
letter, or a picture, but ther have failed to distinguish those smaller charaotera. on whIch the 88D8e of the whole depends. Botb teacher. and pllpll.
have found that Class-Books and Maps are as mdispensable to this department or knowledge, as to that of Geography; and that an artificial globe ie
just as poor a substitute in ODe case al in the other. Instead of the globe,
and a few balls strung upon wires, Mr. Burritt's book Bnd Atlu introduces
the pupil at once to the Grand Orrery of 'he Heavens. and makes him
acquainted with the namel and positions of the bodies which compose It.
He learns to locatf: and to cllunfy liis astronomical knowledge as be does b:i8
I8Ogrftphical; and experience has proved that a child or ten years will trace
out all the constellations that are visible 1n the heavens, and name the
principal stars in each, lUI readilyal he will learn the bt)unciariea of U.
ata&e8 from a map. and I1&ID8 tb8 citie. they contain.
Huntiftgton
4-
Savage's Publicat 'OM.
17
.
----------------------------------------------------~
A NATIONAL 8EOBRAPHY FOR- SCHOOLS-,
IDUitrateci by ao Engravings and eo Stylograpbic Maps; with a colored
GLOB. MA.p, OK • Raw PLAa.
•
One vol. qu.rto.
1
New and improved edition.
By 8. G. GOODRICH, Author of Peter Parley's Talel.
I
This work il designed as a
.eAooI-boo~a
manual for ',ocli",; and notblDl
In the _ "rlt is allowed to interfere with this delip. At the same time, from
the arrangement adopted, it will be found to contain a great quantity of
Qlatter which will render it a convenient family book for reference. Ita
utility, in this respect, will be enhanced by the index at the close of tbe
Yolums.
Biwa,licity, ".,.~, and con",,"-c, haye been carefully studied in the
arrangement of the wbole wor~ Thus the typography, especially tbat
w bien contains the leading ideas" of each lesson, IS clear and conspicuous;
the letteriIlg of the maps is peculiarly full and distinct; the whole view of
each country is brought together, so as not to embarrass the reader by ...
referenee to I8parate pages or separate tablel; distinct ma~ of tbe prla
cipal countries are given, and care bas been taken not to fill tbem with unimJM?rtant names, whicb may bewilder the student, nnd render all his acqwsitiona obscure and imperfect. Too many of the popular achool-bookl
on this subject are made to complUJl two oJ?j,ct. j to combine a univel'BaJ
pOfrapb1 and a school geography in one. Botb objects are not, therefore,
wei attained, for while there 11 not enough for the former, there is too
much for the latter: the eonaequence is incoDYenience and embarrassmeu&
to the teacher-increased study and labor to the pupil, whUe be is imperfectly instructed, if not actually injured in his habits of study. Tb6
mBpa and text of this work contain quite as much 'of detail 88 the pu~il can
remember. Tbe design has lMten to embrace just 80 much, that, If well
studied, the pupil will carry in" his mind olear amd diatinct images of tbe
forma of eountriel, courses of rivers, location of toWnI, cities, ~., 10 that
every country, with ita lead.iDi featurea, can be and- will be permanentl,
mapped on his mind.
In respect to ma~ a new and useful device has been adopted, which we
entitle a Globe JIG,. This, of neceSlity is separate (rom the pages referring
to itl but its great utility and convenience, iD the way it is to be used, cannot raiJ to strike e1'erY practical teacher. It has a handle, and with a tIIOtW
oj tM 8wh. in AU 1&tbi4, the pupil is taught the various names given to the
divis\ons of land and water, the shapes of oceans and continents, and the
relatn'e positions of countries and places upon the face of the earth.
It is, in short. ~ ..,h.lit." lor "" GrtijiciGl 6'1obe. With the advantage of being
toasily handled, and collltantly before the eye, during ,the early stages of
the study.
As Il means of rendering the progreSl of the pupil at once agreeable and
eft'ective, the author haa- endeavored to invest the subject with every tiegree of interest of whicb it is capable. He has sought to keep the attention _
ilive by vivid descriptions; and, in order to convey accurate Impressions of
Visible objects, he has introduced a larger Dumber of illustrative engraviugI
than have ever appeared in" similar treatise. Everyone knows that mere
wordl are incapable of conveyi~ correct and distinct ideas of a.nimals;
am! that a simple cut of a lion, for instance, will be more useful in gl vinK
an impression of his (orm and aspect., than a whole volume o( verbal deICri'ption. The same may be said 01 the countenances and costumes of
1'&.1OUS nations; of tbe peculiar mQ<ies of building, travelling, worshippiq,
b. The engravings, therefore, are not introduceC:l aslnere embellishmenll
ID4 allure menta to the pupil, but. U all emdent. and euentlallOurce ot cor
... iDlormatMm.
Huntington
18
4-
Sawzge'8 Publicatiou.
PETER PARLEY'S NEW GEOGRAPHY FOR
BEGINNERS.
with 18 beautifully colored Maps, and 150 Engravings, aDd DeadJ
bound in stil" covers.
It were needlea to speak of the felicity of style, or of the simple~ clear,
and practical method in which Peter Parley presents to tile young the subjeCts of which be writes. Notwithstanding other workl of the kind baye
been issued. tbia little work, more full and accurate tban any, continues to
make its way in all places wbere improvements in primary education are
,oing forward. It bas been reprinted in Eagland, and is extensively uaed
througbout that country and Ciwada: it haa been translated into French
and is much used in France; it baa been publisbed in Greek, and introdu;;!
to 10,000 youth of that nation. It bas alao been translated by the missionanee
in Persia, and introduced into their achooll, and has been more recenti1 reprinted in Sidney, New South Wales. This foreign use is evidence 0 the
yalue and popularity of the work; yet it is to be regretted that we have DO
oopyn.ht law to give authors and publiab\rs the beneAt of such uae.
InUl~tecl
FAMILIAR LECTURES ON BOTANY,
PRA.CTICA.L, ELEMENTARY, AND PHYSIOLOGICAL:
With a New and FuU Description of the Plants of the United States, aad
Cultivated Exotica, &c. For the Use of Seminari88, Private
Students, and Practical Botanilt8.
By MRS. A. H. LINCOLN,-Row MRS. PHELPS,
.BllfCIPAL 0,. THE PATAP8CO ,.• • "'L. IK8TI'I"O'l'. OF M.aYLAIJD.
New Edition, re.iaed and enlarged. 1 voL imperial lImo.
In the present edition of this work, in compliance with the request of man,
teachers, the "Descriptions of Genera and SpE!cies" are DOW made to include all those native and foreip/laDts which the pupil will be likel,. to
meet with in any part of the Umte States. The author has been anXlOUI
not to omit Southern and Western plants of any interest, and large additionl
wlder this head have been made. Should teachers, or students, observe
such omissions, communications on the subject, made to the author, would
be gratefully received. The author has now tboroughly revised the de8Cri~
bOilS of plants. For the numerous additions made she IS indebted to several
Am£rican works, especially to tbe "Botany of the Northern and MIddle
States," by Dr. Beck; and also to the descriptions of Torry, Bigelow, and
Elliot. For foreign plants, Eaton'llLIld Wright's Manual. Withering's British Plants, Loudon's Encyclopedias, and some other works, have been CODlulted.
For cleamflls, simplicity, and philosophic predsionJ there are few schoolbooks which hold a more pre-eminent rant than Mrs. J.,inooln's Botany: few
certainIf have a wider and more justly deserved popularity. The work ia
divided Into Foua P "'BTS1st. The Analysi~ of Plants, or Lessons in Practical Botany.
td. The Organs of Plants, beginning with the Root, and ascending to the
Flower; or what is termed ELBMBNTA.BY DaTA-NY, and Vegetable Pb,-10 logy.:
3d. The different Sy,tftU of Bot""" and the most impoltant NGtural r ....
'k.; the mOlt interelting genera and families found under each Clul aDd
Ocder.
4th. The progreaiY8 appearance of Plowers in the SeUOD of BloomiDl:
&he Phen~mena 'p~u~ by the cWferen& fiateI of J4ht, A&moapbere. &0;. •
Ueo,rapbical DilUibutiOl&.
"
Huntington
4- Savage'8
Publicationa.
19
Hi~torr of Botanical SCience, and tne Analogies and Contrasts betweeli
organized a.nd unorganized matter in Nature.
A distinguished and experit-nced teacher in natura) science says of tbu
work :-" Far from depreciating other ..,arks on thi~subject, I think my remark will not be invidious, when 118Y, that I think it far better adapted to
the purposes of Eleme'otary Instruction in the science than UD)' I have seen.
I am much delighted wit.h'the easy and natural method by which it intro.
duces the scholar to a knowledge of the first prinCiples or the science, IUlti
the strict philosophical arrangement it employs in imparting instruction.
Tile whole work has the impress of one practically acquainted wit" the aJ"l
of teaching, and adds another proof to the many already existing. that illoItru('Lors of intelligence are generally better qualified to prepare elementary
works than those who have never had any experience in the businesa Of
leaching."
f
BY TH&.fAM& AUTBOIL,
DESIGNED FOR PRIMARY AND COMMON SCHOOLS,
BOTANY FOR BEaINNERS.
AJf DTlLODUCTIOlf TO ..... LINCoLN's BOTAlfY.
By MRS. LINCOLN PHELPS.
1 vol. 18mo. pp. 150.
This book is intended chie8y for the use of primary ecbools aDd the
younger pupils in higher schools and seminariell. So much baa, of late,
been urged by thOle who take an interest in the subject of education, in
favor of introducing the Natural Science. into Common Schools, that it ill
to be hoped that the time is not far distant when plants and minera.ls will be
as familiar objects of study in our district school-house as the spelling-book
DOW is. Perhaps some parent or teacher may be ready to inqwre. whetber
it is recommended that such studies shall take the place of reading, spelling,
or writing; by no means; but every teacher knows that there are many
listless aod vacant momenta when even the most active of his pupils oseeza
tired of their monotonous I!ursuitl; habit and rest»ect for their teacher ma,
lead them to sit still and do no mischief; but it 18 not difficult to perceive,
~y the heavy eye and inanimate countenance, that the intellect 81umbera.
These are the moments when the experienced teacher feels the need of
some new stimulant. Instead then of saying, "John, or Lucy, 1,0u hal·.
been sitting idle this half hour, wby don't you mind ,our book l' he who
understands the human mind is aware that this 11 the very W&Yltill more to
. disgust his pupil, and he will assuredly be read! with some new met.hod of
awakening attention. Suppose, then, instead of a rebuke for idleness, the
teacher sbould kindly addresl his pupil as follows! "You have been 10 10D,
engaged upon a certaiD set of studies, that I perceive ther have become ti....
lOme; I think of introducing a new:study into the schoo ; to-morrow I,laall
II uctur, "" Bo'.,; you may therefore briD, with you to-morrow aU tne
wild lilies, or violets, or any kind of common wUd ftower that you can find
in the fields." The eft'ect~anyone at all accustomed to the care of children
will readily understand. lIut it may be said, "there are many teachers who
are Dot capable of giving a lecture UPOD botany." To this it may be an.wered, that every teacher who ia in any degree fit to be .uch can use tb.
"Botany for Begmners," evell though they never heard a lecture upon the
aubject of botany; it will teach him the leading principles, and he can explaID them to his pupils; this will be ucluriftg Mpoll BotMY.
Thousands are usmg this, little work, and give the strongest testimony m
it. fayor.
The succeSlOr of Mils Beecher in the Hartford Female Seminary say. :.. It Ja 11 clt'&(, simple. and interesting exhibition of the princ:plel or RU 8D
o
"fie
20
Huntington.4- Savage' 8 Publical:um8.
tertaLming lIJCience, adapted to the comprehension of children, for w hOD - .
de81gueu. and Cully capable of preparing them for a more extended trea
It 11 partIcularly recommended ~ the instructor. of our common IChool.. f A
an interesting employment for tbe leisure hours of their scholars; u . .~
mothers, WI an US1StaDt to them in th, great work of storing their chil~
IDI.UJa With the &Dowledge of the woro of their Crea&or."
t,
PHELPS' NATURAL PHILOSOPHY,
i'O& TH& ua& 01' IOBOO1.8, ACADJUD&a, AND PILlVAT& ITUDUT&
Illultrated with numerous EngraYings from ofisiDal desi8MBy MRS. LINCOLN PHELPS.
New Edition. I voL limo..
PHELPS' PHILOSOPHY FOR BEGINNERS.
1 yolo IS.o.
A teaeher of much experience, and Principal of one of our firBt Acad.emi_
UI1,.I of tbese work s ! .
'The 8ubject is treated tn a manner highly scientific: the enp1lvinp d.8lrigned for illustrating the text are bappily chosen and executed; and a delTee of freshnel8 pervades tbe whole work which cannot but impart life and
animation to the t1tudent of its pages. But more than all, we rejoice to_
-' healthy moral feelmg di1I'using ita fr~rance oyer the wbole."
PHELPS' CHEMISTRY.
New Edition. I yolo limo.
PHELPS' CHEMISTRY FOR BEGINNERS.
1 yolo 18mo.
ProfessoT Caswell, of Brown University, baving examined some of the
DJ08t important chapter8 of these works, saY8 :-'i'~ _The principle8 of the
science a~pear to be stated with brevity and clearneu, and are h8ppily ill. .
t.rated by CamiJiar and well-selected examplel."
UlfIVBBSITY BDmOB
01'
DIL WEBSTER'S DICTIONARYI
Abridged from tbe quarto American Dictionary, with Walker's Key to the
ProDunciation of Greek, Latin, and Scripture Pro~r Names, etc. With
a Memoir and Bust of the Author. 1 voL royal duOdecimo. 556 pageL
WEBSTER'S HIGH-SCHOOL DICTIONARY.
limo. 3GO pagel.
The design of this volume is to furnish a vocabulary of the more common
words, which constitute the body of our 1anguage, With numerous technical
terms in the Seiences and Arts, and many wQrds and phrases from otber
languages. which are often met with in Engliih books, with a brief definition of each; to which is added an accented vocabulary of CLASSICAL,
SCRIPTURE, and MODERN GEOGRAPHIC NAMES. The Ortbosnp~y and ProDUDciation .are made to correspond closely with those editlon.
ot the work of the author recently rensed under \he editorship of Profeuor
GOODRICB, of Yale College.
Huntington ~ Savage's PUJ..
WEBSTER'S PRIMARY SCHOOL PIONOUI
With Accented Vocabularies of Clasaical, Seripb
phical Proper Names. Square 16mo. New \
larged, corre8}¥)nding in orthography to the lar. '
This work embraces about ten thousand more wot- .
Dictione:ry, and is especially recommended to the at,
.Also-POCKET EDITION, in several stylel of bin"
and gilt embosled.
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Thil last is a vocabulary of the most important word"
both common and scientific, with a concise, primitive defin~
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word, followed by the derivations of the same word,-thus pres~.. _~_
two features in one, of a defining Dictionary, and one of the Synonyms.
The following Testimonial is subscribed by a large number of the most
distinguished men of our country:
" The subscribers highly appreciate Dr. Webster's purpose and attempt to
improve the English language, bK rendering its orthography more simple,
• regular, and uniform, Hnd by remOving difficulties arising from its anomalies.
It is very desirable tha.t one standard dictionary shdUld be used by the nu·
merous millions of people who are to inha.bit the vast extent of territory belongin, to the United States; as the use of such a standard may prevent the
formatIon of dialects in states remote from each other, and impress upon
the language tmiforaity and atability. It is desirable, also, that the acquisition of the language should be rendered easy, Dot only to our OWIl. citizens,
but to foreigners who wish to gain access to the rich stores of science which .
it contains. We rejoice that the A...mcan DictUmary bids fair to become
Inch a standard; and we sincerely hope that the author'S elementary books
for primary schools and academiel, will commend themselves to the general
use of our fellow-citizens."
THE PRACTICAL FRENCH TEACHER.
"
NORMAN PINNEY, A.
~.
The leading peculiarity tn this work is, that it exercisel the studen~
throughout in the constant practice of speaking. The preparation of every
1es80n is a preparation for speaking the ianguage, and every lesson is an
actual conversation in it. These conversations. too. are progressive and
I1stematic ; commencing with the simplest elements of the language, and
advancing by an easy process, to the more ditlicmlt. The wbole has been
prepared with a view to overcome the difficulties which an American meets
in acquiring a knowledge of that 10 necessary part of a finished educatioD.
KEY TO PINNEY'S PRACTICAL FRENCH TEACHER.
THE FIBST BOOl[ Dr FIlI1WOB; or, A' PrRctieal IDtroduetion to the
Reading, Writing, and Speaking of the French Language. By NORMA.N
Plln.BY, A. M.
PICTORIAL
PICTORIAL
PICTORIAL
Pl~ORlAL
PICTORIAL
HISTORY OF THE U. STATES, ~y S. G. GOODRICH·
HI~wroRY OF FRANC~" by S. G. GOODRICH.
HISTORY OF ENGLA1~D bJ S. G. GOODRICIL
HI~RY OF ROM~J.. by ~. G. GOODRICH.
HI8TORY OF GREu.;E, by 8. G. GooDRICH.
The above series of histories, formerly p'ubJisbed by Mesars. Sorin k Ba)).
of Philadelphia, is very extensively introauced into both private and pub1i4Institutions througbout the Union.
20
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1&.4- Sa'Oage' a Puhlicai:um8.
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ada t"O# MECHANIC', COMPA.NION I
IiClence,
p",.
deslgneo. and Cully caps.): of 8uper1lces and Solids i tables of Squares aad
It ~ partlr.~arly r8CoDlDlube RoOtI; Circumference and Areas of (...'11'01_ •
all mLerestmg employm·.l Powel'l; of Steam and Sleam Engines ;
mothers, as an aaalstaD~ Statel Weilrhts and Meuurea- .&.•
Js WIth the lwowl~
-0
-Y~.
•
mill
:BY J. K. SCRIBNER, A.. II.
E L ~Q. . . .0 papa. Morocco, &ilt. with tucka.
PH
tty recommended by leveral diltinguished civil engmeera
roa THE UP' .Dd. as a Manual for practical mechanics, 18 a work 01
t!'~sides the general topic$ already enumerated. it contams •
11l1U!'of valuable matter, in relation to Centres of Gravity; Gravlta.. . ;diel; Pendulums; Specific Gra\1ty of Bodies; StrenJth. Welgb\.
.. awl Crusb of Materials; Water Wheels, H)'dl'08tatics; Hydrauhcs ; ~t1C8;
Centr. of Perouuion and Gyrati0l;l; Friction; Heat; 'rabies of WeIgb&a ul
Metals; Pipes, Scantlings; lntere~kc
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tartlLlnlDg
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THE ENGINEER'S, CONTRAC'foR'S, AND SURVEYOR'S
POCKET TAPLE-BOOK.
BY J. II. SORIBNER, A. II.
1M papI, Mmo. Tuck bJndiDl, with gilt ed,..
The above work compri8el Logarithms of Numbers, Logarithmic 8in"p.I'
ul(l Tangents, Natural Sme. and Natural Tangents; the· Travene Table, Dud
it full and extensiYe set. of tables, exhibiting at one Yiew the number or eu..
UIC Yards contained in auy embankment or cuttins, and for any base or slope
of sides usual in practice. Belides these essential tables, the work comprlse8
60 cagel more of Mensuration, Tables, Weights of Iron, 8trengt;h of. MatefIB 8, Formulas, Diagrams,. etc., for laying out Railroads, Canala. and
Curves; much of which has never before been oft'ered to the publio, and kll
indispensable to the engineer. This book will prove a great saving of tUlle.
and "'iii enable the new beginner to furnish relul! accurately (and .. " ..
mnch greater rapidity) as the most experienced in
profession, without u.aid. '1'Ile tables of lOfarithms. etc., have been care u11y corrected and C('rupared wlth different editions of the same tables; and all the tables throughout the book have been read carefully by proofs four timea; hence the moe
impliCit conAdence may be placed in their correctne8L
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KAME'S ELEMENTS OF CRITICISM.
I yo1. bo.
t)- Tbe only edition which received the latest reYilion of t.he Auther.
·PRESTON'S BOOK-KEEPING,
DouaLB ARD SINGLB BlfTR Y.
PRESTON'S INTEREST TABLE••
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,. per cent.-Large and Abridged. 7 per cent.-Larp anc.l Abridged.
An7 valuable Boob to he IIad lD .ewTor~ will be taaishecl b7 B." . . at the Lnred Guia Pric-.
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The End.
World Public Library Association