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POPULAR
Telescopic
HOW
TO
AND
Astronomy
MAKE
A
WHAT
TO
TELESCOPE
2-INCH
SEE
WITH
IT,
BY
A.
Dtmonsttafor
FOWLER,
A.R.C.S.,
0/ Astronomy^
F.R.A.S.,
College of Science^
Royal
London.
ILLUSTRATED.
THOMAS
R
O
Y
NEW
WIIITTAKER,
2
"
K
3,
1896.
\All Rights
Rese"ved\
"J
I
"
:
BIBLE
HOUSE.
DEPARTMENT
l"LAJSJi
OF
STANFOED
EDUOATIOr
JUNIOE
UNIVERSITY
PREFACE.
The
aim
of
telescope
have
the
the
how
equal
brought
within
finished
of
recreation
will
be
found
of
beauties
that
such
its
by
the
of
of
revealing
and
of
the
practice
is
who
those
themselves
indicate
to
briefly
telescope
a
of
of instruction
amount
telescope
of
of
provide
and
A
scenery,
ounce
reach
to
maximum
use.
celestial
"an
the
astronomical
an
telescope, or
a
quite capable
the
how
instrument,
obtain
can
power,
show
inclination
or
possessor
and
realise
is to
means
highly
a
little book
be
may
not
with
this
inches
2
aperture
of
many
the
observer
worth
larger
will
soon
of
pound
a
theory."
The
is
method
similar
to
and
Practiced
with
great
Norman
use
described
that
Work
in
Lockyer's
courses
both
The
Eyre
the
in
my
small
"
book
of
own
and
attend
who
Astronomical
of
objects
for
but
I
price
Is.
at
South
is
observation
in
Spottiswoode,
adopted
Professor
Physics
experience
instruments,
is followed
Demonstrations
Physics*
students
selection
and
telescope which
Astronomical
entirely on
large
the
in
the
by
almost
of
constructing
success
Kensington.
based
of
teaching
am
the
indebted
iv
PREFACE,
Celestial
Webb's
to
valuable
C"ymmon
for
for
Telescopes
much
information.
For
the
with
the
benefit
the
be
to
indicate
attention
possible
I
the
whereabouts
the
is
than
of
been
thought
and
naming
of
maps
complete
more
the
may
beginner
himself
for
but
stars,
the
on
acquaintance
has
it
astronomy,
chapter
first
stars
not
are
ciently
suffi-
to
necessary
the
tification
iden-
objects
to
which
directed.
is
Finally,
a
their
making
of
include
of
intended
those
study
to
the
of
outdoor
advisable
put
Objects
that
say
in
the
and
have
I
path
right
making
chiefly
for
endeavoured
seeing
as
to
much
from
deductions
correct
as
observations.
his
I
have
suggestions,
to
thank
and
Mr.
assistance
C.
P.
in
Butler
reading
for
proof
several
sheets.
A.
London^
October,
1895.
valuable
Fowler,
CONTENTS.'
I.
CHAPTER
MAKE
TO
HOW
A
TBLESOOPE.
PAOK
Optical
of
parts
and
tube
cell
The
tube."
for
The
required.
"
the
of
the
"
object-glass.
the
Squaring
Focussing.
"
Works
distances.
of
The
Draw
telescope
1
II.
FEW
HINTS.
"
field
Estimation
of
of
view.
angular
lists
Working
reference.
"
The
power."
weather."
Observing
"
eye-piece."
image
Magnifying
"
telescope
"
CHAPTER
A
The
"
instrument
completed
inversion
The
object-glass."
The
adapter."
stand.
Materials
telescope.
a
.12
.
CHAPTER
HOW
Star
star
names."
LEABN
TO
THE
III.
NAMES
Star
seasons.
"
maps.
CHAPTER
to
the
observe
the
Sun."
Sun's
STABS.
THE
How
to
"
the
use
18
maps
.
SUN.
Sun-spots."
rotation."
OF
IV.
THE
How
.
The
The
faculae.-
inclination
of
the
To
strate
demon-
Sun's
axis.
"
To
zones."
mark
out
Sun's
the
of
Periodicity
and
poles
Sun-spots."
The
equator."
Eclipses
of
the
Sun-spot
Sun
29
.
CHAPTER
THE
An
interesting
"Earth-shine."
study."
The
The
"
.
V.
MOON.
varying
appearances."
Seas.""
Craters."
The
Ring
terminator.
Mountains
and
POPULAR
ASTRONOMY.
TELESCOPIC
CHAPTER
HOW
Optical
of
a
distant
lens
is
called
the
the
As
coloured
flint
are
the
such
to
For
be
a
limited
same
serves
of
image
an
of
combination
or
lenses,
Technically,
the
first
O.G.,
while
the
objective,
or
lens
simple
a
this
of
consisting
those
by
of
effects
colouring
of
the
convex
lens
of
curvatures
the
scope
tele-
a
plano-convex
the
of
in
double
a
or
combination,
properties
surrounded
are
employed
concavo-convex,
number
of
for
the
perfect
more
of
the
parts
one
of
kinds
two
are
other.
the
glass
nearly
as
Such
as
lens
a
is
achromatic.
but
at
a
neutralised
lens
convex
the
form
to
object-glass
one,
optical
that
possible
said
In
lens
image.
by
the
and
glass.
and
lenses
formed
lens
crown-glass
a
essential
"
eyepiece.
compound
a
lens,
a
this
fringes,
is
of
(2)
(1)
"
object-glass,
images
The
telescope.
are
the
TELESCOPE.
A
a
magnify
to
constitutes
second
by
and
object,
which
with
of
telescope
refracting
a
MAKE
TO
parts
I.
These
lenses.
time
to
give
eyepiece
eyepieces
are
a
made
large
of
astronomical
an
are
obtained
nearly
field
double
ordinary
an
purposes,
scope,
tele-
by
achromatic,
of
view
by
a
bination
com-
and
using
of the
lenses
The
placed
for
For
the
O.G.
the
eyepiece.
These
the
distance
the
adjustment
need
be
the
for
focus.
A
wooden
commended
re-
astronomical
J inch
results
focal
length.
1\
diameter,
inches
their
focal
made
for
method
inch
length.
varying
order
methods
possible
J
positions
proper
eyepiece, in
Besides
"
making
of
here
give
to
doing
indicated
the
lenses, the following
telescope according
a
the
to
:
"
papier-mache
of
better
will
length.
and
the
cheapest
3 inches
provision
that
length.
absolutely.
for
given
focal
in
The
focal
the
course,
and
diameter
and
inches
even
of
about
lens
A
"
O.G.
required.
instructions
tube
are
quality.
1 inch
and
infinite,so
required
A
diameter
mounted
between
Materials
will
in
other, and
followed
be
not
1 inch
be
to
each
almost
are
better
1 inch
lens
30
of
although,
;
of
diameter
A
are
to
lens
lenses
eyepiece.
length.
lenses
purpose
lens
in
1 inch
respect
this
small
a
qualities, but
various
the
A
"
additional
an
in
with
are
lens
had
beginner's
the
focal
with
be
obtained
For
of
construction
focal
apart.
easily procured,
are
2J"iiich achromatic
A
"
is to
serve
A
of
ratio
distance
proper
which
certain
a
"
This
For
the
of
glass
the
at
lenses,
following
telescope :
of
kind
same
and
lengths,*
ASTRONOMY.
TELESCOPIC
POPULAR
2
zinc, 27 inches
or
cylinder (No. 1) 12 inches
long, 2J internal
long,
a
diameter.
little larger in
very
than
O.G.
meter
dia-
(say
Vj in.).
"
(No. 2)
"
6
A
"
larger
trifle
""
than
"
(No. 3)
,,
^th
6
"
"
of
an
in
eye
inch
larger
than
Several
sheets
Thick
of brown
paper
eye
in
meter
dia-
lens.
cartridge paper.
or
to make
sufficient
cardboard
diameter
lenses.
about
discs 3^ inches
half-a-dozen
in
diameter.
Paste
glue.
or
Indian
ink
Beady-made
obtained
*
The
a
very
focal
sun,
/ rrlce
or
other
Jiat at
end
well
as
reasonable
length
lens
ink.
stencil
tubes,
of the
distance
of the
at
or
of
from
as
rate
a
lens
a
piece
distant
of book.
may
of
object.
the
wooden
from
be
paper
the
cylinders and
can
be
Publisbers.t
readily determined
on
lenses,
which
it
produces
by
measuring
a
distinct
the
image
HOW
The
telescope
be
must
inches
; but
required
made
of
O.G.
an
tube
where
by rolling brown
mahogany,
The
which
of
may
the
on
an
inch
not
be
greater
of
only
wanted,
on
is
than
the
diameter
probably
single
a
should
inches.
one
be
may
sible.
acces-
be
about
of the
The
be
27
is most
tube
should
about
long cylinder
whichever
the
paper,
ment
instru-
they
a
of
2^
exacUy
if
glue
tube,
diameter
if made
tube,
brass
a
It
are
the
be
focus.
made
with
paper
internal
eighth
an
or
inches
several
of
should
it
ready
3
tube
main
and
of 30
a
TELESCOPE,
The
rigid,
purchase
to
A
tube."
very
for
long
cheaper
be
MAKE
TO
O.G.,
thickness
nearly
of
of
quarter
a
inch.
an
Tubes
of
made
sheet
also
zinc
the
answer
purpose
very
welL
The
cell
of
the
place
at
part
its
rub
used,
the
the
In
the
on
each
press
remove
Trim
of
which
and
1,
is
of
roll
a
the
the
tube
from
the
ends
of
be
will
the
about
sufficient
longitudinally
A*
patched
when
them
O.G.
the
A
{seeFig. 2).
nearly
as
tube
*This
will
method
be
well
glue
rolling the
at
smaller
diameter.
before
cylinder
tube
and
six
inches
B
them
put the
time
be
of
complete
and
good plan
to
quite dry.
pieces, each
two
these
Calling
fit
to
and
cut
nicely
A
out
inside
object-glassbetween
in
spent
right angles
at
that
paste,
or
halves,
two
wooden
removal
a
a
it is
long.
enable
and
is
it in
cut
into
little extra
the
It
possible.
in
cylinder
the
the
to
laid
facilitate
to
applying
as
possible
involves
arrived
by
as
deal
a
paper
again,
up
if
the
this
lens
thickness
a
the
before
the
On
tube, give
respectively, divide
B
; and
of
object
principal
such
to
tube
chalk
firmly
as
the
support
tube
rolling the
layer
The
telescope tube.
main
French
cylinder
to
paper
the
it with
tube.
turn
end
nicely inside
it fits
object-glass."
instrument
No.
cylinder
the
for
to
the
making
the
length
of
out.
least
internal
expense,
tubes
on
but
the
another
same
wooden
result
may
cylinder
be
of
POPULAR
4
As
adornment
an
of
consisting
attached
eye
has
"
lens, while
focal
be
a
diameter
inches
the
pieces
in
a
tube
equal
with
the
be
may
of
From
of
inch
an
d
diaphragm
the
No.
inner
between
this
them,
outside
off
piece
a
O.G.
cell,
it slide
tube,
c),and
long {h and
on.
make
to
lenses
the
of the
enough
this
so
3 ; cut
case
should
the
and
"
of the
sum
with
to
field
"
lenses
until
2
in the
out
cut
piece.
No.
the
the
inch,
cylinder
as
of
is half
one
cylinder
that
that
piece,
eye-
close
comes
eyepiece,
be
negative
or
eyepiece
extra
should
and
^f ths
a
flange
a
card
stout
which
them
first
our
on
to
uncut
about
of
lens
between
for
remainder,
inside
instrument,
one-third
long (a.Fig. 1),and,
slit the
the
Huyghenian
length
distance
paper
is
of
is, the
; for
apart
to, the
Roll
"
thus,
:
the
that
distance
inches
two
referred
2^
the
In
"
focal
a
lengths
end
object-glasscell.
lens
eye
ASTRONOMY,
thicknesses
two
or
eyepiece.
the
this
to
one
the
to
The
the
TELESCOPIC
two
cut
them
insert
being
of
made
g
Pig.
thin
card
inch
may
e
ink
in its
deep,
he
glued.
inch
an
or
place by
cut
op
brass, and
half
indian
with
-Detah^
sheet
about
centre
lens
or
1."
from
stencil
means
the
(fall size).
Eyepiece
the
having
a
clean
Blacken
diameter.
ink,
of
a
and
when
dry,
ring, about
remainder
Similarly, support
of
cut
the
the
an
small
field
hole
in the
the
inside
fix
the
of
eighth
tube
lens
/
eye
;
in
an
this
its
HOW
place by
do
case
of
piece
a
tube
it ;
glue
not
MAKE
TO
end
of
5
TELESCOPE.
half
g
be
the
'
inch
an
it should
the
project beyond
A
long enough
tube,
outer
in
long, only
this
slightly
to
facilitate
to
its
removal.
It
remains
now
and
eye
lens,
of
cardboard
diameter,
It
lens.
If
by
with
a
central
at
be
eyehole
at
that
to
of
the
slight modification
in
of
As
the
lens.
eye
placed
of about
The
of
the
cost
inch
an
a
in
which
cap,
clean
to
the
1.
it will
field
focal
be
at
on
looking through
detected
once
is to
provide
On
the
for
the
that
Fig. 2), and
thick
by
and
a
six
of
means
about
10
The
that
inches
should
eyepieces
the
have
increases
an
rapidly
inches
on
from
the
tube
of
such
No.
3
and
the
axis
The
larger.
in
of
draw
to
ness
thick-
(D,
tube
inch
nearly ^th
latter
F^ glued
the
and
a
cylinder
Fix
part
object-glass.
principal
make
to
care
the
the
long.
flanges F^
this
inside
nicely
(A)
of
object
telescope tube,
roll another
1
slide
of
with
The
its distance
firmly
very
position
the
as
shown
smaller
tube
to
tube
should
be
long.
instrument."
completed
blackened
in
to
the
be
must
inch.
an
adapter."
No.
tube
Fig. 2, taking
parallel
for
a
diameter
lenses
diaphragm
of
only require
smaller
the
be
diminishes.
adjusting
it will
the
eyepiece
cylinder
the
already stated,
and
connect
; it will
of
will
eyepiece
extra
consequence
lenses
length
the
described
one
quarter
a
the
Draw-tube
as
of
necessary
Fig.
the
of
apart, and
inch
an
aperture
in
of
edge
construction
general
similar
D
in
central,
not
one
it is
A,
cap,
form
the
disc
simple
a
-f^thsof
about
in
be
the
over
eyepiece.
The
as
hole
time
a
either
may
made
any
as
eyehole centrally
an
This
be
is shown
the
it.
may
darkening
a
the
to
removed
be
may
close
it
or
place
to
internally,the
Fig. 2, showing
a
various
section
Finally,
parts
of
the
may
be
instrument.
after
put
being
together
It
\xv^^
6
POPULAR
ASTRONOMY.
TELESCOPIC
O
UJ
o
"L
HOW
MAKE
TO
be
found
of the
tubes
with
others
by rolling thin
possibly
they
as
All
sand-paper,
found
are
the
dead-blacked
be
with
If
this
for
preferable
outside
The
embellished
or
The
with
the
a
for
made
horizontal
direction.
This
of which
two
A
in.
5
consists
of
right angles
about
cut
an
inch
so
as
to
E,
C
and
through them,
tight ;
in
a
the
nut
its
at
a
adjustment
must
and
desired
any
various
ways,
of
be
may
IJ,
X
any
for
attaching
other
object
wood-turner
a
made
in
hard
wood
C
6
the
is fixed
C
the
part
upper
connected
allowing
be
D
by
to
about
end.
extreme
B
thumb-screw
and
left.
If
A
1^
X
B
on
C,
ins. in
A
and
nut
is
1J ;
X
2", should
at
be
2", when
;
is fixed
it when
on
and
may
A
firmly
thumb-screw
a
turn
of
not
together
for
upright
which
used.
screwed
8x2,
a
indicated
1^, 2" 4J
X
to
be
way
be
throughout, except
are
right
more
vertical
in
in
at
made
or
services
thick.
shorter
for
Provision
pointed
be
pieces, each
should
screw
with
of
and
kind
indispensable,
arrived
fence,
a
4
admit
D
lamp
enamel,
some
telescope, a
be
fairly
wood
half
out
of
in., i?
; the
of
the
may
some
two
stand
with
proved
im-
described.
support
4
X
be
with
painted
employed.
be
may
the
Fig. 3, provided
about
to
it may
If
the
obtainable,
E
that
top
hand.
to
comes
in
of
here
the
sash,
is
ink
may
be
almost
are
powers
simple arrangement
window
A
is
result
are
prevent
stencil
mixed
varnish,
"
movements
so
one,
to
fancy.
to
instrument
two
ink,
instrument
it may
or
;
stand.
high
the
shellac
black
telescope
especially when
be
of
according
supporting
stencil
should
lenses
the
readily obtainable,
appearance
vegetable
or
easily.
too
or
of
according
them,
between
ink
some
purpose.
by coating
black
Indian
reflections.
internal
tubes
of
diameters
the
over
paper
stifflyor
parts of the
inner
of
thickness
the
increase
to
or
pieces
fit too
to
reduce
to
necessary
7
TELESCOPE,
A
passing
not
screwed
length, working
are
similarly
which
be attached
will
by
nected
con-
admit
sccewa
POPULAR
8
by
or
bracket
a
held
be
may
Fig.
that
so
up,
they
the
must
small
not
it
the
Of
readily
suitable
place, or
most
fence
a
so
much
required
single
fence
be
a
for
will
both
on
tripod
stand
screwed
position
; but
prevent
the
the
object
if the
insufficient
sides
of
by fixing
overcome
about,
be
keeping
be
the
moved
to
as
post,
When
can
of its
slip out
up
right-of-way
difficultycan
object they
not
movements
not
to
readily be
can
telescope
straps.
attached
desired
screwed
a
small
two
the
certainly satisfactory.
the
to
be
by
instrument
course,
has
observer
is
telescope will
continuous
view.
E
on
object, and
arrangement
made,
pointed
when
and
place
this
freed
convenient
any
its
shows
are
screws
to
in
if well
and
in
4
ASTRONOMY.
TELESCOPIC
a
it ; but
in
post
the
it if firm
replace
may
this
enough.
Fig. 8."
For
but
turned
a
lower
the
nicely
attached
a
on
as
Parts
of
wood
part
vertical
desired
a
Simple
support,
of
C
Support.
Tblesoopb
D
is turned
and
and
E
remain
hollowed
cylindrical support,
either
to
a
tripod
stand
out
which
or
before
as
post
to
may
; this
;
fit
be
is
BOW
shoTn
TO
j9 in
at
MAKE
A
and
Fig. 3,
TELESCOPE.
again
on
9
in
stand
tripod
a
tbe
frontispiece.
Vig.
The
the
at
inversion
be
once
ordinary
that
seen
day
would
as
be
the
the
to
this
action
of
cause
puzzling
First,
then,
(Fig. 5a),
the
a
let
beam
down.
corrected
by
and
light
of
the
which
is
is
no
In
ing
insert-
the
piece
eye-
extra
lenses,
telescope,
objection
it
one
much
as
content
are
will
absorption,
collect
to
it
by
astronomical
an
there
indeed,
light
things
to
see
to
it,
long
so
mind.
is
of
those
to
in
astronomers
in
of
surfaces
Hence,
borne
the
the
object,
objecl"glass
loss
a
of
and
Although
as
involves
from
down,
is
the
is
through
looking
upside
appears
inversion
functions
possible.
it
this
between
this
On
terrestrial
any
image
disadvantage
a
chief
upside
as
since
Sdppobt.
image."
at
teleacopea
reflection
by
the
the
lenses
but
;
Tblbscopb
instrument
additional
of
of
completed
and
Simple
i."K
not
the
a
text-book
lenses
inversion
versed
not
it
of
be
raay
of
the
in
parallel
rays
be
not
image
optical
understood
optica,
on
that
few
a
of
out
place,
not
seems
words
a
as
little
matters.
if
we
impinging
have
upon
a
lens,
it in
L
tbe
POPULAR
10
direction
same
rays
a
the
as
which
point F^
TELESCOPIC
from
diverging
parallelbeam.
lens
F
the
from
be
lens
for
called
upon
focal
the
the
Next,
same
if
we
direction
the
the
of
which
to
a
point)
a
the
but
glass
action
of
parallel beam,
axis
this
of
point
the
will
other
or
The
from
very
the
lens
F
distant
and
the
is made.
(Fig. 56), not
lens, they
be
of
Lbnsb"
Telbscofb
not
as
this distance
surfaces
two
T
as
of the
distance
lens, and
of the
lens
lens, according
is,rays
of
have
as
that
the
parallel,the point
the
diverging.
length
the
from
not
from
and, similarly,
;
side
be
the
to
converge
focus
one
curvatures
Showing
will
emerge
on
rays
parallel rays,
optical propert^iesof
Fig. 5."
J?' be
or
lens
will
farther
or
converging
objects, is
F
if the
are
rays
depends
to
the
principal
point
a
; but
nearer
the
the
Whether
is immaterial
will
of
axis
is called
ASTRONOMY.
will
in
the
in
still
axis
the
verge
con-
of
CHAPTER
A
examine
the
first
results
definition
is
angles
it
circle
of
signs
any
of
of
considerably
If
the
guard
to
this
of
out
the
is
length
first
and
twice
field
eyepiece,
has
if
show
it
before
ceeding
pro-
himself
the
fitted
and
in
of
the
object-glass
its
place,
be
must
care
If
the
focal
focal
compound
of
been
product
lens
divided
equivalent
of
length
the
eyepiece,
telescope.
the
the
described,
of
the
by
focal
12
focal
their
of
length
"
the
the
and
the
taken
defect.
a
power
which
eyepiece
lens
of
magnifying
rectly
cor-
evenly
an
and
putting
spiky,
appear
the
by
focus
be
star,
corrected
tightly
too
power.
divided
be
equivalent
the
be
this
against
purposely
right-
this
square,
convince
may
be
square.
will
stars
Magnifying
glass
by
be
be
The
at
bright
observed,
should
it
possible
not
if
a
O.G.
be
observer
object-glass
of
images
The
the
will
light
ellipticity
further.
importance
If
best
is
see
to
should
object-glass
it
To
telescope
focus.
of
the
is, if
telescope.
the
direct
out
illuminated
the
the
to
employed.
if
that
;
telescope
lenses
the
"
of
if
affected
on
proceeding
the
interest,
from
seriously
axis
placed,
observe
obtained
Before
determine
to
squared
"
the
to
order
most
properly
not
of
objects
in
be
will
HINTS,
object-glass."
various
tested,
be
FEW
the
Squaring
IT.
eyepiece,
the
objector
quotient
the
For
of
lengths
Thus,
will
be
"
the
gives
form
equivalent
sum.
length
the
of
focal
the
for
eye
the
FEW
A
HINTS.
13
2x3x1
.
,,
"
for
and
the
second
,
li inches.
=
"
g
^
"
2xlixi
=
.
focal
if the
Then,
magnifying
the
with
O.G.,
For
of
be
60
with
of
length
be
focal
of
and
20,
of
length
the
increases
eyepiece,
of
the
of
both
powers
will
second
and
length being
the
simple plan,
from
powers
20
simply
fourth
will
referred
the
while
with
the
field
will
hand
at
himself
sequel,
and
20, 30, 40,
as
the
power
has
the
field
the
provided
has
the
magnifying
a
observer
In
that
meaning
give
as
near
eyepiece
magnifying
if he
to
pretty
inch,
an
described.
eyepieces
be
60
to
first
the
eyepiece
this
"y
the
well
very
kept
lens
remaining
second
the
if in
Thus,
answers
is
object
of
examination
the
in
lens
simple
a
the
as
its focal
times.
range
increase
the
inches,
will
eyepiece
especially
field.
30,
lens
"eye
long
so
the
of
focal
planet,
a
removed,
be
power
a
or
eyepiece,
lens
first
30
be
objective
general,
purposes,
stars
centre
the
In
of
the
power.
many
double
an
40.
reduction
magnifying
of
with
second
or
i
+
length
power
" "^^^"
=
"
H
these
the
60,
alone
lens
is
employed.
The
on
with
powers
For
one.
to
60,
but
will be
results
The
when
The
beginner
observing
if, while
will
true
is
such
observing
see
the
apt
an
with
image
to
one
however,
which
of the
as
eye,
the
he
the
then
be
120
or
may
good
very
a
of
power
20
is
be
moon
keeps
observed.
magnification
the
evident.
stars,
gives satisfactory
apparently projected
amplification will
100
as
objects to
under-estimate
object
double
and
object-glass be
power
for each
high
as
if the
lowest
indicated
planets,
powers
observations,
many
effective.
most
the
up
the
craters,
occasionally employed
be
he
lunar
spots,
sun
object-glassesperform satisfactorily
achromatic
cheap
or
the
on
A
a
planet, but
other
the
power
open,
sky,
and
of 60
POPULAR
14
for
will show
instance,
the
to
TELESCOPIC
in
Jupiter
diameter
apparent
ASTRONOMY.
of
this
the
moon
about
be
to
way
with
seen
as
equal
the
aided
un-
eye.
Some
and
2-inch
for
objectives have
with
these,
will
powers
however,
is
and,
the
on
be
the
each
increased
whole,
by
the
the
reduction
30-inch
40
This
of the
lenses
inches,
magnifying
one-third.
by
a
of
length
eyepieces,
same
accompanied
focal
a
gain,
field of
view,
perhaps
are
to
be
preferred.
field
The
of
view
is
^The
"
half
about
a
the
(in England)^
horizon
the
star
a
When
the
of
case
brought
the
to
on
of
centre
above
be
may
will
the
give
diameter,
circle
great
a
is under
examination,
the
field
of
the
where
view,
as
it should
that
crater, it is important
lunar
a
four
to
time
40"
field
by
moon,
of
hours.
particular object
any
divided
field
the
about
the
360"
traverses
24
aiid
corresponding
arc
the
Or,
across
pass
seconds
of
in
sphere
diameter.
south,
to
of
situated
so
celestial
the
number
of minutes
number
since
star
the
and
noted,
due
nearly
required by
of the
by observing
in
degree
a
diameter
angular
estimated
roughly
be
may
which
view.
of
in
be
tion
defini-
is best.
Focussing.
sufficient
best
to
inside
that
on
be
care
and
of
does
is
observers
if not
too
focus,
it
the
eye
perform
not
great
variation
is apt
is
draw
tube
both
it is
only
in this
way
If
to
its functions
in
It
the
found.
be
can
as
unless
employed.
are
of
means
best
focus, especially
the
to
powers
its
at
seen
the
only
strain
moved
itself,and
under
the
best
focus
for
different
is the
best
guide
surprising.
weather.
Observing
kind
for
be
regard
true
focus,
the
The
conditions.
the
of the
place
proper
consequently
to
eyepiece by
outside
side
one
will
with
taken
the
move
the
object
higher magnifying
the
when
^No
"
of
"
sky adapted
thick,
are
by
no
Experience
for
means
observations.
detrimental
Fogs
for
or
as
haze,
observa-
of
tions
the
sun,
for
of the
views
a
It
the
is
this
but
purposes,
of stars,
the
as
nights
less
of
from
the
of
to
favourable
un-
Excellent
through
small
on
for
that
case
for
astronomical
for
observations
than
large telescopes, and
observing
nebulse.
distances.
In
"
heavenly bodies,
they
are
which
so
worth
it is sometimes
recognised
while
bearing
moon
are
each
slightly over
stars
which
form
the
the
defining
degrees
many
are
ever,
This, how-
unsteady.
very
when
frosty nights,
the
often
other
or
clear
means
are
therefore
and
sun
nebulse.
especially good
no
stars
is
that
angular
state
well-known
It
by
best
planets
convenient
obviously
frequently obtained
are
are
effect
the
are
Estimatioii
positions
is
images
far
has
and
comets
imagined
sparkling,
are
planets, though
as
named
16
haze.
or
commonly
stars
such
things
objects
slight fog
and
moon,
such
HINTS.
FEW
A
minutes
or
without
culty.
diffi-
in
that
mind
half
in
degree
a
diameter.
three
The
which
sometimes
are
for
employed
the
same
in
stars
the
(Fig. 6), are
be
can
all the
5
is about
wishing
to
For
AlmanaCy
as
this
to
this
for
the
between
the
the
two
Pole
star
they
as
purpose,
distance
also
justify
to
Perhaps
nearly
; the
better
none
a
these
between
it tells
professional
little book
are
for
him
him
this
data
to
be
he
which
The
more
the
wants
are
star
little
than
the
published
than
is handier
astronomer.
intended
is
telescope,
able.
indispens-
purposes
which
what
a
almost
general
exactly
with
possessing
almanac
an
almanac
beginner
burdening
Anyone
"
it, will find
Whitaker'a
of
shilling.
the
use
is
There
without
reference.
of
edition
round
year
distance
2),
degrees.
Works
and
point
be
may
made
be
degrees.
adapted
better
even
seen
which
Plough,
thus
angular
three
(seeMap
Yardstick,
and
The
is about
stars
extreme
two
the
as
purpose,
popular designation.
the
to
known
of Orion
belt
maps
at
Nautical
to
know,
chiefly of
included
than
a
an
use
in
intro-
POPULAR
16
duction
TELESCOPIC
the
to
constellations,
sufficiently detailed
are
objects
to
these,
the
Among
smaller
with
excellent
his
observatory
with
the
in
objects
much
hours
that
and
what
to
he
order
and
work
goes
to
to
his
shall
do
beforehand
is
in
such
only by
be
can
advance
to
it
for
get
we
much
reference
a
in
valuable
student
the
carefully prepared
investigation,
of
Atlas
astronomer
as
examined
be
to
of
so
fine
list
A
line
doubt
any
late
bodies.
and
evening,
the
by
stars,
heavenly
systematic
clear
a
removes
that
few
the
The
"
"
particular
preparation
the
available.
are
furnish
the
desired
"An
and
moon
of
be
Atlas,"
will
they
most
it
useful.
most
the
If
atlases
Ball,
to
as
instrument.
indicates
any
of
on
list
his
the
of
places
Star
that
hoped
made.
be
New
"
Robert
Sir
lists.
working
of
maps
"Working
the
one
the
excellent
many
information
valuable
"
is
by
Astronomy,"!
will
ones,
Proctor,*
A.
it is
though
indicate
to
reference
beyond
go
R.
which
to
ASTRONOMY,
accomplished
observation
in
this
country.
Even
find
it
excellent
an
imitate
the
himself
of
of
instrument,
of
time
which
course,
the
follow,
visible
make
such
in
be
times,
*
or
30
Longmans
an
having
times
"
As
prepared
instrument
an
telescope,
when
Co.
the
price 5s.
,
to
example,
for
only
field
in
of
observations
an
f G.
in
eyepiece
lens
the
list
is
PhUip
"
various
observer
as
the
Son,
lowing
fol-
February,
magnifying
removed
the
to
chapters
the
a
list
a
powers
the
enable
such
for
such
according
visibility
to
prepare
on
given
are
of
times
2-inch
a
lists.
might
with
the
to
data
will
time,
magnifying
especially
Sufficient
as
the
to
of
and
included
objects
more
telescope,
saving
astronomer,
The
and
2-inch
great
a
according
vary
year.
objects
to
list.
modest
and
advanced
more
would,
the
his
plan,
working
a
with
beginner,
a
:
"
price
15s.
20
A
FEW
Working
List
Stars"
Double
HINTS.
for
17
February.
Arietis.
K
7
11
X
Gteminorum.
Monocerotis.
"
Cancri.
S
CepheL
K
Ononis.
i
S
Star
Clusters
Ursae
Majoris.
Pleiades.
Double
Praesepe.
M
34
PerseL
M
35
Geminorum.
Cluster
in
Perseus.
"
M
NebxQsd
Great
Majoris.
Canis
14
Kebula
Orion.
in
"
Andromeda.
"
"
Planets
(1895)"
Venus.
Jupiter,
Occasional
Objects
Aries.
in
Mars,
in
(1895)"
Gemini
Maximum
of
the
variable
star
Mira.
III.
CHAPTER
HOW
Star
When
visible
of
matter
probably
that
of
much
as
than
stars
system
some
to
be
to
and
naming
but,
as
hemisphere
one
But
if
even
is
it
with,
evident
them
identifying
of
;
3,000.
deal
to
clear
a
number
the
in
as
these
on
countless
visible
number
the
sky
imagine
alone
eye
amounts
more
no
naked
fact,
never
had
one
the
to
the
at
easily
might
one
STABS,
THE
OF
looking
"
evening,
stars
NAMES
THE
names.
moonless
a
LEARN
TO
be
must
devised.
Since
the
stars
for
positions
of
names
long
very
divided
been
times
preserve
these
and
the
the
on
of
corresponding
and
countries,
star
as
The
as
the
the
of
the
ones
a
Twins
employed,
at
the
upon
town
;
to
out.
the
the
the
various
For
a
is
clear
sary
neces-
sphere
surface
to
into
particular
any
constellations
the
letters
Bull
;
separate
of
the
though
not
18
always,
in
are
and
so
Latin,
on.
for
stars
the
"
Greek
alphabet
"
usually,
only
celestial
earth's
given
the
Taurus,
the
it
tained,
re-
city.
of
least
the
name
or
given
identification
the
of
division
look
of
logical
mytho-
conveniently
constellations,
divisions
as
usually
Gemini,
brighter
to
name
names
For
are
to
of
use
them
regard
to
the
dying
The
from
representing
fast
is
maps
derived
still
are
of
remote
very
constellations.
chiefly
names
custom
star
understanding
been
these
although
called
relative
same
from
have
they
groups
have
groups
sources,
figures
periods,
into
the
nearly
very
in
the
order
of
POPULAR
20
tures
identified
are
such
the
as
of
what
stars
Right
and
of
north
degrees
Star
depend
the
country,
horizon
northern
north-east,
Some
of the
from
be
may
for
night.
in
exactly
the
as
round
the
which
we
the
4
mean
see
earth
a
degree
time
a
the
sun
a
earlier
and
do,
evening
will
on
each
of the
fact
stars
of
sun
at
be
of
however,
be
times
of
time
at
ances
dist-
about
will
be
be
west,
time
earth
of
travels
celestial
we
see
the
day,
as
sphere
looking
As
year.
days,
to
seen
earth
one
the
365
are
will
visible.
part
in
(the
so
the
any
the
that
course,
and
towards
that
succeeding
degrees
stars
throughout
sun
50
position, their
set
will
overhead.
same
Some
the
in
different
the
that
so
being
"
the
the
of
near
London,
must,
about
part
vary
"
day,
the
the
year,
clocks, which,
movements
east,
of
round
travels
minutes
apparent
the
same.
of stars
groups
once
in
the
down
than
at
the
time,
one
nearly
of
sky
at
in
heavens
appear
more
change
moon
consequence
sun
from
nearly
certain
in
Again,
the
and
sun
them
remain
be
They
of the
part
for
towards
not
round.
places.
the
low
latitude
the
apparent
Pole
the
night only
away
this
those
in
year
looks
one
rise
to
seen
it will
different
a
During
from
hours
set
the
all
if
year,
six
"
the
that
at
it will
later
never
"
seen
looked
the
Pole
the
in
appear
hours
constellations
to
reckoned
Thus
; six
another
in
are
find
soon
observation.
may
Right
equator.
constellations
of
its
hours, minutes,
are
will
observer
constellation
a
in
celestial
the
time
the
upon
this
of
positions
apparent
of the
The
"
scope
tele-
a
terrestrial
to
are
Declinations
the
by
which
reckoned
is
while
south
seasons.
latitude
R.A.,
time,
of
possessor
measurements
"
and
or
or
the
these, however,
;
sufficientlydefined
is
Declination
Ascension,
Argelander
aperture.
star
longitude
seconds
in
inches
general catalogue,
some
individually
a
and
in
of
catalogue
two
cases,
Ascension
number
a
concern
only
all
In
by
great
scarcely
will
ASTRONOMY,
TELESCOPIC
that
rise
nearly
reckoned
by
regulated by
turns
360"
is,
in
the
24
BOW
hours,
TO
LEABN
degree
one
t.6.,
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of
about
so
hours,
2
o'clock
the
at
8" o'clock
the
on
the
at
end'
of
the
end
of
and
way,
it
identifying
celestial
of
the
well
equally
those
at
in
given
each
maps.
other
surface,
with
of
sort
the
in
one
hemisphere
and
this
Planisphere,
special
In
the
the
nearer
for
the
the
at
for
is not
middle.
*
Published
stellations
con-
8, 10, and
of
in
at
at
12
this
in
assistance
of
The
determining
of
hour
any
does
any
almost
this
Such
stars
on
tables
in
with
as
omy,"
Astron-
on
a
too
will
great,
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to
the
be
be
may
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employed
long
so
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show
all
forms
of
the
little
the
stars
the
stellations
con-
scarcely recognisable,
using
such
admirably
the
not
reason
by
and
world,
spherical
they
maps
to
respect
commonly
attempts
one
the
The
maps.
adapted
best
for
its
guide
for
defect
of
stars.
the
at
top
the
of the
this
individual
the
times
Lessons
those
to
edges
projection employed
stars
and
Nevertheless,
example, though
2, 3, 4,
Maps
of
accuracy
remembered
is
purpose,
learning
the
be
must
about
cost.
single chart,
a
towards
sky
10
at
purpose.
globe.
map
on
south
precisely represented
If, however,
distortion.
due
arrived
Elementary
of maps
each
by
south
means
smaller
projection, similar
covered
area
due
at
be
to
amount
showing
Planisphere^
sufficient
construction
the
similar
celestial
a
ready
positions
be
only
on
as
a
The
"
can
represented
some
serve
will
the
month
a
dates
are
21
particular evening.
in
object
much
The
month,
a
be
meridian
any
very
are
will
the
STABS.
minutes
chap^r,
visible
Lockyer's
"
352,
Art.
Star
a
this
they
the
4
which
each
and
year,
of
month.
furnishes
any
In
that
stars
also
globe
in
day
of
hoped
the
situation
the
in
is
minutes).
month
a
on
appear
beginning
THE
stars
of
which
P.M.
the
beginning
the
OF
intervals
that
at
maps
4
in
these
the
at
NAMES
THE
end
is to
of
the
In
Map
by
G.
of
this
increase
the
the
the
distances
compared
as
maps
1,
chapter,
constellations
Pbilip "^oti,
y^^^*^*
between
with
near
those
the
edges
the
of much
lines
have
Since
omitted
the
the
found
in
to
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use
with
is
Charles's
and
that
which
Major
of
when
the
balancing
and
lines
be
1).
estimates
of
horizon
One
a
of
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1
to
memory.
1
Map
connect
repetition
their
"
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2, 3, and
equator.
to
4
Maps
are
4
show
of
connection
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only
stars
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line
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"
Pointers
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gotten
for-
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6.
side
Fig.
of the
of
stars
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other
passes
Almost
Pole
Star,
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form
by imaginary
way,
constellations
to
be
will
above
be
the
each
Perseus
and
below
will
of
the
of
the
the
Pole,
celestial
sufficientlyserve
Map
1,
will
maps
It may
the
examples
surrounding
to
other.
as
stars
joining
those
regarded
stars
edges
the
connecting
lines, and
down
and
of
2, 3, 4, respectively with
at
sky,
to
never
nearly
in this
habit
to
the
stars
Vega, Capella,
Maps
northern
of observation.
of
some
Dipper,
them,
principal
by imaginary
constellation
stars
time
Ursa
"
opposite
the
the
be
first
of
if they happen
difficulty,
falls into
naturally
the
^the
indicated
distance,
will
should
observe
"
planet.
a
1897
of
stars,
stars
as
the
on
in
between
Star,
much
the
at
found
Proceeding
(Map
without
found
the
Pole
as
Plough,
Next,
these
Cassiopeise,the
of W
the
as
be
distance
Plough,
found
be
sort
north
the
through
will
the
times
4
about
of
two
end
it
on
should
map
constellation
the
recognised.
once
through
drawn
of
will
the
Acquaintance
"
to
respect
represented
on
the
conspicuous
seven
Declinations
identify
to
known
This
not
to
up
maps.
variously
not
simplicity,
with
be
cannot
taken
portion
Wain.
consists
be
of
and
positions
they
planets
VI.
made
be
the
Chapter
How
their
bright body
a
sake
will
maps.
that
should
of
positions
the
Ascensions
Kight
these
if
Hence,
noticed, steps
The
of
in
defects
these
For
planets change
maps.
be
or
the
stars, it is obvious
star
but
consequence.
indicating
been
ASTRONOMY.
compressed,
somewhat
are
found
be
a
TELESCOPIC
POPULAR
22
be
worth
and
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In
using
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^
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{Map
be
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map
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date
the
on
map
4)
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ia
handle
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Star
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ne"rlj
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;
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STABS.
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stars
Square
drawn
Maps
linos
Great
THE
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thb
(Map
of
curve
through
a
along
third
of
and
Arcturus
the
the
;
line
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side
eastern
a
of
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Ploooh
that)
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6."
Fig.
OF
NAMES
THE
LBABN
TO
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or
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12
be
or
p.m.
due
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;
POPULAR
24
For
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If,
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for
instance,
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If
be
indicated
at
the
way
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refers
sides
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situation
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of
position
only
of
those
on
of
its
by
star
a
to
give
an
place
the
such
and
must
ordinary
of
object,
given
used
map
latitude
of
in
its
its
exactly
be
and
ably
prob-
hood.
neighbour-
the
would
as
information
whatever
in
view.
will
of
stars
scope
tele-
power
map
declination,
be
ated
estim-
observed,
be
to
said
the
field
source
brighter
is
and
15),
large
is
any
mentally
complete
more
R.A.
maps
will
to
magnifying
a
here
the
to
the
diflSiculty
cluster
be
lowest
unless
it
in
90")
no
star
(p.
to
the
necessary,
it
telescope
will
referred
a
must
nearly
from
stars,
the
distance
comet,
it
very
from
certain
a
order
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overhead.
mentioned
not
small
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position
to
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object
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employed
to
21).
in
38^"
principal
accordingly,
readily
stars,
remains
those
example,
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directing
already
aid
pointed
first
for
will
equivalent
subtracted
the
in
Sirius,
the
with
being
point
experienced
be
desired
the
of
Star
while
latitude
knowledge
north
the
(the
being
explained
Pole
times,
through
a
of
the
all
at
London
pass
With
to
that
place
same
already
map
positions
hour
one
as
the
mind
in
latitude
in
of
case
borne
the
month,
a
the
evening
the
interpolation,
half
the
of
hours
by
of
In
be
other
ASTRONOMY.
TELESCOPIC
nature,
numbers
the
used
longitude.
same
to
find
HOW
TO
LEABN
NAMES
THE
Map
OF
THE
STABS.
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POPULAR
ASTRONOMY.
TELESCOPIC
Map
2.
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-fip.
^"5
60
28
POPULAR
TELESCOPIC
Map
ASTRONOMY,
4.
IV.
CHAPTER
SUN.
THE
At
certain
is of
the
additions
heat
to
the
for
observer
himself
light
the
by
How
to
take
little
or
density;
small
in
fitted
inside
and
a
so
much
neutral
the
better
according
In
made
general,
by
the
sun,
the
tint
the
when
a
the
magnified
to
the
at
dark
conditions
of
larger
will
29
be
formed
piece,
eye-
suitable
observation.
be
can
obtained,
the
observation.
telescope
so
should
the
cover
of
piece
eye-
with
glass
to
the
the
is
sufficient
blackness
time
of
The
image
a
telescopes
observations
image.
to
smoked
be
if
safe
plane
glass
green
also
can
of
made
flame
sun
or
this
however,
projecting
candle
a
there
of
perfectly
is
When
eyes.
glass
piece
which
the
the
always
must
directly,
dark
is
small
cap
of
to
to
at
aperture,
sun
a
method
little
adopted
are
the
with
A
;
brought
he
to
inches
2
observing
with
of
piece
devices
than
this
brightness
density,
to
smoked
the
If
a
proving
necessary,
that
injury
against
instrument.
an
for
winter
is
"
observer
covered
merely
It
sun.
more
in
been
and
ment,
instru-
in
satisfaction
have
light
little
our
great
no
of
scope
tele-
a
others.
guard
not
danger
no
be
be
is
telescope
of
use
with
giver
great
which
would-be
to
though
much
the
the
precautions
the
of
observe
warn
and
facts
the
labours
to
outset,
of
interest,
the
find
will
some
sun
the
from
follow
to
the
of
knowledge
likely
are
possible
greatest
our
of
observation
the
times
required
Special
employed.
are
should
sun
being
on
be
directed
a
sheet
of
POPULAR
30
will
image
held
card
or
paper
image
A
The
the
the
frame
but
not
short
made
to
is shown
in any
the
from
and
image,
the
eyepiece,
thrown
Sun-spots.
exhibits
It
"
visible
to
the
part
is
naked
much
there
size,it
called
and
the
is
a
nucleus
will
than
The
the
still
other
outlines,
times
and
only
be
may
necessary
the
screen
of the
size
the
at
paper
should
be
part
frequently
in
as
the
are
the
Some
almost
to
most
be
that
seen
the
as
varied
seen
in
and
if of
rule,
a
the
spot
times
Someis
of very
are
concentric
two
be
which
umbra^
spots
to
central
penumbra.
of the
scope,
tele-
and
part of
the
sun
the
sun-spots,
darker
is
part
with
part, and,
outer
and
the
large enough
the
are
spot.
that
case
even
inner
exhibit
the
readily be
darker
of the
they
are
the
outer
regular forms, appearing
at
tube,
sunUght.
it
velvet
or
a
about
the
of the
examined
These
eye.
darker
umhra^
of
setting
cloth
when
spots
distinctly outlined.
is the
for
often
very
occasionally they
considerable
any
is
dark
certain
and
card
of
distance
;
frame.
the
over
of
pins
travel
to
direct
adjustment
of
piece
A
angle.
proper
from
the
of rotation
movement
a
of
admit
to
made
or
itself ; it is
slightly changing
which
telescope,
frontispiece, but
suggests
work.
frame-
to
of the
piece
paper
the
in
which
way
for
provide
drawing
is to
image
light
a
object-glass end
the
at
the
screen
frame
a
fitted
ployed,
em-
obtained
board,
body
A
tube.
the
be
be
by drawing
rotated,
be
cannot
down
square,
help
Such
it
and
up
attached
the
20
the
of
thin
a
focus
eyepiece.
means
of
be
can
the
projecting
on
fairly stiffly
fit
that
so
for
made
be
sketch
the
from
telescope by
may
should
inches
will
to
for
way
the
to
screen
paper
inches
the
to
power
will
the
from
necessary
If the
of
size
card
in diameter
arrangement
screen
a
14
of the
trial.
by
The
eyepiece
3 inches
of about
convenient
attach
12
about
image
distance
a
of the
position
found
behind.
distance
the
upon
be
must
an
at
the
ASTRONOMY,
distance
some
depend
eyepiece, and
the
TELESCOPIC
circles
;
irregular
groups.
The
SUN.
THE
umbra
is sometimes
often
change
examining
the
details
effective
very
is viewed
of
when
eyepiece
the
When
the
be
swallow
less
no
miles,
of
dimensions
a
image
The
FaCUlSB.
be
sun,
there
than
the
noticed
of
rest
It
somewhat
in
demonstrate
can
instrument,
A
to
the
and
series
in
forms
easily be
many
of
be
move
the
sun's
near
the
will
quently
fre-
size.
it
of
the
brighter
/aculce, and
of
spots
of
are
seen
near
the
sun
of
consequence
of
centre
by
of
; if
is
the
That
rotation."
regarding
drawings
of the
atmosphere.
sun's
the
corded.
re-
about
made
much
limb
in
centre,
demonstrated
facts
the
can
been
boundary
are
all
across,
is
spots,
c"Ued
are
that
miles
be
apparent
which
that
that
have
or
the
perhaps
observed
the
of
appears
spot
readily
neighbourhood
the
which
they
diameter
limbj
These
the
and
across
be
may
added
absorption taking place
rotation,
will
near
than
enable
reflects
of
sun's
addition
the
be
may
darker
globe
the
the
disc.
the
especially brilliant
limb.
miles
irregular patches,
are
do
should
if
if he
hundreds
some
reduce
that
these
sun-spot
smallest
The
which
In
"
to
scale
earth,
estimate
will
due
will
such
A
observer
that
spot
any
that
sun
any
mind.
100,000
rough
fact
the
tremendous
whole
is
than
may
of the
the
addition.
in
edge, foreshortening
noted.
be
screen
directly, see
the
the
up
planets
860,000
massive
the
If
in
to
Remembering
To
found
be
round.
borne
impressive
more
spots
the
will
60
the
once.
sun
is turned
telescopicallyobserved
and
at
the
viewing
should
other
be
on
observing sun-spots,
phenomena
could
For
hours.
telescope, when
movement
distinguished
when
it
few
a
power
eyepiece, but
apparent
suspected
the
2-inch
of the
of the
be
to
all
the
spot,
a
of
course
spots produced
lenses
partake
them
of
common
a
the
the
on
not
the
are
directly.
Some
dirt
on
in
which
by bright bridges^
crossed
to
seen
81
the
our
means
this
sun,
the
system
is
of
small
rotation
our
can
indicating
in
be
the
POPULAR
32
positions of
The
before
he
"
"
top
the
and
the
afternoon,
The
north
the
and
passes
limb
is that
towards
the
at
with
sun
right
the
After
the
rule
relatively
the
of
of the
image
comes
to
be
the
image
is
to
say,
by
hand
western
of disc
is most
meridian
a
great
a
; the
poles
eastern
as
look
we
limb
is
on
Turn
the
by
one
is
sun
the
furnishes
spot,
a
be
centre
or
diameters
the
as
that
the
western
the
of
circle;
this
times
of
in
sun's
the
parent
ap-
motion
will
in
motion
this
of
the
sun's
then
the
limb, and
telescope
be
is
is
movement
means
the
;
the
distance
in
until
by
and
one
apparently
image
round
screen
of the
will
fact
of
Placing
different
at
variation
telescope, its
and
fills
different
sheets
on
eyepiece
just
the
the
diameter
the
image
of
convenient
right angles.
at
slightly
line
the
the
the
west
northern
When
by
the
this
adjust
As
the
shown
of
diameters
be
screen,
drawings.
direction
while
respectively
are
left
in
right
orientation."
"
cut
is
the
size
circles
consequence
to
and
as
that
on
eye,
screen,
will
in
year,
east
disc
celestial
or
trial what
diameter.
an
east,
limb
called
be
the
require
the
the
that
so
adjustment
across
of
marking
might
towards
sun's
through
naked
two
the
on
screen
the
the
of
hand.
and
these
of
centre,
(say 3 inches), draw
of
their
far, however,
means
What
sun.
sun's
the
finding by
paper,
if the
of
time
very
some
got away
points
the
of
drawings
points
the
which
circle
have
the
lower
passing through
the
that
disc, and
the
proceeded
of the
will
south
and
upper
"
that
so
show
the
on
enough,
necessity
bottom
mid-day
at
top
places
have
not
the
perceives
will
day,
to
determined.
will
"
day
long
be
can
observer
ASTRONOMY,
apparent
continued
across
passage
spots from
their
be
drawings
a
the
change
spots
TELESCOPIC
along
apparent
edge,
is
ment,
move-
in
advancing
the
the
orienting
edge
slightly
the
edge
which
will
raised
one.
sun
is viewed
inverted,
so
that
directly through
the
eyepiece, the
the
will
appear
four
points
as
in
THE
when
Fig. 7b;
Fig.
projected
on
Fig. 7."
view
Direct
naked
with
the
taken
Having
for
lettering them
On
will be
that
seen
from
the
disc
and
15, 1892,
large spot
visible
a
disc
sketches,
E.
by
while
8."
Sun-Spots
in
seen
on
Imaqb.
orient
details
the
of
positions
the
Astronomical
an
Telescope.
Screen.
a
to
of
sun's
in
image
various
the
spots,
each, numbering
or
in
visible
sun's
new
a
on
op
sketches
Fig.
8.
both
days,
rotation
February,
was
c
group
movement
made
will
It
days,
successive
on
apparent
an
Two
W.
shown
the
made
sketches
spots have
to
are
Sun's
of
the
W
Fig.
in
as
reference.
the
was
S
b As
in
such
comparing
N
precaution
sketch
afterwards
N
projected
As
mark
indicated,
way
S
Orientation
Eye.
e
and
be
W
8
the
will
they
screen
a
7c.
W
a
33
SUN,
b
was
between
brought
across
on
be
seen
carried
the
to
dates
our
Feb.
11
that
the
off
the
of
the
view.
E
1892,
HiLUStratinq
Sun's
it
rotation.
POPULAR
34
As
TELESCOPIC
sun-spots
travel
do
enough
to
eastern
limb.
The
the
the
drawings
period
travel
would
that
is
apparent
the
earth's
of
inclination
The
will
found
be
The
spots
the
disc, according
observations
while
paths,
March
in
of the
the
plane
the
sun.
fact
in
sun
"
determined
north
northern
the
that
with
the
the
sun's
travel
the
time
about
they
J days.
27
in
spots
the
same
rotation
is less
made
degree
a
; but
from
of the
the
is, the
of
the
for
the
day,
the
extended
the
equator
is referred
side
curved
This
the
axis
sun's
makes
sun's
makes
of
to
its
the
sun's
will
the
with
stration
demon-
ecliptic
"
of the
The
to
the
journey
round
is about
6",
perpendicular
from
of
to
as
Hence,
spots.
course
to
round
perpendicular
the
;
the
equator."
annual
during
south
journey
depart considerably
disc
to
but
they
perpendicular
and
observations
appear
the
obvious
an
is not
a
the
September
its annual
axis
which
towards
is
all.
across
they
paths,
poles
sun's
in
year
; in
is this
paths
December
lines
north.
sun
latter
and
have
Nor
different
the
convex
plane
of the
of
straight
earth
point
axis."
in
June
earth
by prolonged
pole
to
the
the
out
which
in
that
inclination
plane
since
days,
days
it increases
In
the
in which
mark
actual
the
25
over
that
they again
towards
convexity
To
disc
the
curved
to
made.
are
traverse
the
little
a
and
1
nearly
roughly
14
being
the
on
the
sun's
long
poles.
the
have
of
last
average
orbit
to
seen
again
in
its
of the
rate
shown
have
observations
to
is
period
rotatiou
mean
in
Allowance
the
at
circuit
time
time.
movement
the
under
travelling
be
determine
to
On
whole
true
round
be
not
of them
many
utilised
little
a
the
the
than
to
in
earth, however,
so
be
it must
necessity
come
rotation.
make
direction,
to
also
disc
the
of
disc, but
even
sun's
apparently
The
and
may
of the
across
the
across
this,
will
spots
same
completely
formations,
evanescent
are
that
expected
ASTRONOMY.
the
a
the
year,
plane
Fig. 9."
drawing
made
the
for
axis
equal
25
is drawn
ca
the
crosses
semi-minor
the
us
is
centre
at
E'Q
an
centre
the
as
of
table,
indicated
If it be
and
the
and
in
desired
25,
is drawn
at
of
e'6q
By
this
disc
has
to
is
a
heliographic
NCN'
of
tude
lati-
made
is
a
to
to
this
line.
the
CQ,
and
ah
north
point
of
where
the
semi-ellipse with
it
latitude
south
of
case
right angles
construction
a
the
position angle
the
angle
h is the
sun's
the
and
G^**to
Then
in
The
J" W.,
March.
in
table
1892.
The
angle
the
this
S.
6J"
axis, and
axis.
of
25
Equator
and
use
is
parallel to e'q.
made
by
the
date
this
J", and
Axis
March
on
the
of
Sun's
Thb
illustrates
9
Fig.
ASTRONOMY,
TELESCOPIC
POPULAR
36
pole
is
is
equator
ch
as
evident
the
that
of
6^" S., as
required
is
presented
towards
diagram.
determine
longitudes
of
the
with
spots,
some
use
the
tudes
lati-
made
of
precision
may
be
THE
Thomson's
The
belts,
zones
or
These
extend
from
limits.
becomes
This
Periodicity
of
equally
numerous
means
extending
and
in
wane
together
; while
naked
the
to
The
it is
probable
until
maximum
show
if
the
is
two
equator.
sun's
the
outside
these
and
equator
which
might
wise
other-
be
to
seen
From
paratively
com-
free
it has
of
they
the
sometimes
no
tained
ascer-
spots
for
spots
wax
time
a
generally
are
protected by
been
Near
from
by
are
observations
1 1 years.
quite
of
weeks
be
to
seen
being easily visible
smoked
glass
the
about
number
of
reached
or
a
venient
con-
again
will
spots
the
about
end
and
1893,
steadily diminish
end
of
and
increase
of
the
reach
present
another
1904.
telescope
a
of
Sun-spots
"
about
be
will
they
about
Hence
of
occurred
that
when
century,
in
fog.
minimum
a
side
the
magnitude
numerous,
eye,
the
when
are
of the
occur
of
occur
centuries,
maximum
maximum
last
spots
times.
two
and
may
at
London
each
on
latitude
all
at
day, large and
every
south
sun-spots.
than
disc
the
spots
9 ; spots
Fig.
high
period
a
minimum,
that
number
the
that
rarely
I., p. 75).
equator.
more
over
35^
a
the
to
near
5^ to
in
as
have
to
appear
that
one
Journal
or
observations
quite apparent
in
drawn
are
and
about
it is very
and
equator,
fact
the
north
Vol.
Continued
"
revealed
one
of Astronomy^
Association,
ZOnea
have
surface
37
Atlas
Astronomical
sun-spot
sun's
axis
(see BM'a
discs
British
of the
SUN.
sun-spots
on
is not
every
to
be
condemned
occasion
that
it is
if it
fails
applied
to
to
the
sun.
Eclipses
present
us
spectacles
of
of
the
with
one
that
can
extremely
is not
to
be
taken
to
the
rare
sun.
These
of
the
be
conceived.
of
that
the
earth
when
Unfortunately,
at
our
phenomena,
magnificent though
most
occurrence
expected
ends
"
any
modest
to
total,
fleeting
they
given place, and
instrument
observe
total
as
will
are
it
be
eclipses,a
POPULAR
38
TELESCOPIC
passing
reference
however,
that
visible
in
will
be
there
be
in
seen
sujQices.
be
total
29th,
then
and
that
it
will
1896,
9,
It
Japan.
total
a
state,
to
Aug.
on
Siberia,
1927,
and
country,
interest
eclipse
Zembla,
June
of
be
may
a
Nova
until
this
It
will
Norway,
not
ASTRONOMY.
last
only
will
eclipse
for
few
a
seconds.
Partial
common
the
The
usual
the
disc,
its
perhaps
ThQ
forcibly
eclipses
the
supposed
are
tharii
there
going
on,
surface.
could
is
sun
be,
to
spots
the
that
it
is
a
grand
indicated
as
us
our
nothing
turns
phenomenon.
body
black
across
the
sun's
spots
which
lie
along
moon's
edge
such
on
furnish
on
be
will
very
occasions.
of
particulars
is
it
the
inclined
an
varying
would
instrument
!
over
in
demonstrate
that
body
change
the
to
easy
scattered
cyclical
more
scope
tele-
sliding
the
immaculate
by
the
intensely
the
telescope,
not
little
year.
indiscriminately
not
Surely
teach
simple
a
the
observer
the
comparatively
our
of
one
will
during
seen
with
Thus,
the
diary
or
be
to
of
upon
almanac
Any
by
ruggedness
impressed
interest
gradually
one
of
are
occasions
taken,
watched
eclipsing
path.
that
be
may
the
to
being
precautions
moon
such
on
add
materially
however,
sun,
and
occurrence,
will
of
of
eclipses
the
amount
be
it
once
was
axis,
that
his
disc,
the
and
disturbances
of
spotted
justified
if
it
CHAPTER
V.
THE
An
interesting
satellite
is
which
have
the
moon."
but
of
the
in
the
which
moon
that
of
it
the
interest
Even
a
detail,
construction
of
and
great
a
their
ating
fascin-
most
make
to
views
standing
Notwith-
world,"
the
awaited
always
20
of
of
the
is
about
30
or
powers
many
lose
turn
re-
with
telescope.
of
with
man
aid.
its
in
"
beautiful
'^dead
is
our
patches
while
the
by
a
a
power
the
worth
of
quarter
possessing
magnifying
is
sake
called
first
to
of
obtained
often
so
anyone
of
amount
is
the
be
may
moon
by
for
only
it
the
patches
one
and
dark
in
larger
alone
eye
belief
remains
heavens,
if
telescope
naked
various
popular
these
moon
the.
the
showing
the
to
Telescopically,
objects
small
To
"
object,
rise
given
prominence,
a
study.
beautiful
a
MOON.
reveals
from
40
a
the
100,
to
formations
lunar
vast
be
can
investigated.
The
from
distance
The
round
while
moon's
the
moon
its
fying
magni-
a
the
happens
us,
As
we
that
"
earth
distance
according
see
the
full
moon
moon,
the
to
half
turns
this
moon,
on
is
sun
how
its
is
month,
a
once
towards
turned
and
time,
to
the
is
which
one
any
so
Hence
diminish
appearances.
revolving
presented
It
to
appear
miles,
2,000
miles.
240,000
nearly
will
varying
hemisphere
at
60
moon
miles.
4,000
body,
the
is
us
of
power
to
of
diameter
a
dark
the
only
illuminated
is
hemisphere
or
axis
other
in
phases.
the
same
POPULAR
40
that
time
it
the
than
7", and
W.
The
effects
near
the
edge
detected
and
there
in
the
nature
by
continuous
of
the
peaks
various
be
to
is
sun
the
on
of
from
to
employed,
illumination
the
again
us.
appear
At
setting
irregular
of
before
observed
sequently,
Conance
appear-
the
higher
the
valleys
The
when
"
by
of
of
scarcely
dark
the
these
larger
have
must
of
relief
nator
termi-
the
the
noticed
disc
the
old
is
"
part of the
earth
to
on
times, owing
than
dark
to
ones
to
moon
the
the
of
soon
the
in
when
necessary
that
feebly visible,
moon
especially noticeable
it is
the
reflected
whole
is
and
of
is best
appearance
This
and
darkness.
in
out
Along
conspicuous bright points
very
Everyone
"
sunlight
objects
as
ary
bound-
to the
it cuts.
some
time
full.
near
them.
the
arms.
to
some
appear
moon
rise
moon's
for
features
Earth-sllilie.
giving
telescope ;
some
falling almost
are
very
the
light standing
far
a
views
at full.
which
moon
presents
with
lunar
the
ascertained
half,
moon,
sunbeams
the
that
so
it is
full
differently
near
is not
moon
be
uneven
general
given
name
and
hardly
be
best
it is
more
apparent
very
only
when
if before
of
terminator
thus
is not
new
the
points
illuminated
and
when
the
us
the
when
is the
that
; so
most
The
can
observed
rising
are
illumination,
This
darkness
viewed
of the
after
be
"
moon
are
rings
obtained
sented
pre-
8" E.
could
to
Though
only
can
about
measurements.
markings
observations.
full
beneath,
is
without
libra-
"
varying
of
indeed
of
are
when
and
conditions
the
most
disc,
changes
different
horizontally
or
the
small
the
see
sometimes
are
angles, never
appears
the
if after
moon
naturally
light and
line
the
always
we
of
displacement
a
these
terminator.
of
this
of
middle
features
The
of
that
so
consequence
surface
moon
of the
is also
of the
true
In
poles
of
the
rugged
under
earth,
slightly different
at
us
ASTRONOMY.
the
face.
same
tions," however,
to
round
goes
the
nearly
very
TELESCOPIC
telescope
a
add,
fact
and
that
exactly
this
that
is due
moon,
new
the
to
the
back
bright
same
THE
of
size, the
bright
crescent
circle
larger
diameter
of
The
to
the
of
water,
the
Seas."
"
naked
and
the
have
we
of
"coast-lines"
the
separately
of
"ay
named.
these
the
be
to
erroneous,
retained.
of
number
Sinus
the
attract
tracts
Thus
""c.,while
latter, the
likely to
is most
Colours,
a
visible
are
represent
Imbrium,
certain
a
Among
to
conveniently
Mare
to
part.
known
now
is still
Crisium,
Mare
belong
to
appears
darker
the
is
this
(maria)
sea
moon
formerly imagined
though
"
"
name
41
great dusky patches which
were
eye
the
than
The
"
MOON,
along
bays
are
Iridum,
attention
or
of the
beginner {see Fig. 10).
Tlie
first
glance
full, will
near
circular
called
greatly
in
ones
are
ones
Walled
are
of
these
classes
the
Ring
as
a
craters
balloon.
and
similar
in
and
but
The
Mountains,
similar
of
recognised.
are
Craters^
as
shape
resemble
as
much
100,
50
as
that
so
miles
the
so-
to
the
in
their
ring
teriors
in-
in
diameter,
scale
of
these
that
of
their
than
greater
smaller
take
ones
science, such
named
of
many
their
of
in the
learning
a
most
Sketch
to
Map
from
times,
of the
half-hour.
and
these
on
such
men
as
the
of
Foucault.
craters
Moon
after
of
many
modern
more
striking
recognise
pleasant
past
named
Kepler, "fec.,while
names
the
been
of
Schiaparelli,Lockyer,
as
forty
have
philosophers
Copernicus,
occupy
three
formations
and
astronomers
process
appear
much
is
Archimedes,
and
number
from
would
not
analogues.
larger
Nearly
immense
an
it be
seas."
"
than
more
features
terrestrial
noted
of
shallower,
craters
are
remarkable
classed
of the
of the
some
size, and
much
floors
Several
they
as
PlaitiSy though
are
the
The
Plains."
telescope,if
a
presence
distinguished
are
mountains,
while
the
volcanoes
smaller
larger
with
moon
Walled
ellipticalcavities, closely resembling
or
vary
The
the
at
reveal
of terrestrial
They
and
Mountains,
Ring
Craters,
are
represented
(Fig. 10),
the
If further
moon
and
the
itself
will
identifications
rOFVLAB
TELESCOPIC
AGRONOMY.
POPULAR
44
TELESCOPIC
11.
Fia.
and
moon,
an
that
Atlas
115
miles.
is
is
by
Mountain
earth,
their
lunar
so
on.
in
our
in
most
are
Four
sketch
identifying
imposing
craters,
Plato
working
60
found
on
their
find
of
the
the
map,
and
them
when
is the
the
near
added
be
and
Ptolemy
lunar
craters
this
but
action,
is at
analogues,
Apennines,
observer
the
Apennines,
familiar
will
so
that
Mont
ranges
have
with
on
Blanc,
are
no
terminator.
which,
on
mostly
These
moon.
bling
resem-
ranges,
are
conspicuous
more
the
To
size.
may
miles,
that
we
terrestrial
the
it
mountain-
which
the
Alps,
in
hypothesis.
few
A
"
with
from
we
the
of volcanic
those
be
to
names
map
results
Ranges.
somewhat
of
across,
convenient
a
reduction
generally agreed
the
really represent
all events
miles
55
Shadows.
apparent
scale
the
means
no
Lunar
"
consequent
of
idea
give
It
the
ASTRONOMY,
take
our
and
indicated
difficulty
By
the
the
far
craters
the
in
THE
the
immediate
when
seen
reach
a
about
of
height
The
Bills
of
the
with
2-inch
a
Mare
Rays
streaks.
or
Near
"
reveals
particularly noticeable.
a,lmost
give
Tycho
as
a
mountains
far
the
one
pole.
The
Kepler.
Another
when
passes
straight,
and
known,
and
may
"
southern
part
without
of
full moon,
the
streaks,
or
one
Tycho, being
crater
that
conspicuous
so
even
meridians
they
radiating
is
centre
immense
the
from
crater
tracts, through
interruption.
apparent
So
satisfactory explanation.
the
"
the
sun,
through
Like
dark
other
earth
casts
this, there
bodies
in the
shadow,
a
is
and
eclipse
an
of
moon.
it is very
Although
lunar
eclipse,such
visible, even
red
taken
faint
of
to
to
courses
the
During
phenomena
the
be
of
rays
occultations
the
close
darkness,
to
the
moon
the
of very
remains
with
light which
traversing
comparative
seen
not
mostly
moon
after
observing
are
watch
to
totality,shining
during
light,due
their
interesting
The
importance.
of
of
over
Moon.
of
moon
are
pass
without
neighbourhood
a
the
ance
appear-
Hyginus
rays
important
rays
of the
Eclipses
the
from
These
valleys,
remain
the
the
are
of
time
bright
impression
long
or
they
Cleft
the
certain
apparently radiating
system,
little
a
into
have
It lies in the
telescope.
the
striking.
very
of these
the
seen
curve
sometimes
"
bouring
neigh-
Vaporum.
opera-glass
"an
of them
conspicuous
be
may
features
1,000
the
ridge bordering
and
is
are
than
of
magnificent
lunar
which
More
bent.
most
seen
These
"
curved
this
parts they
some
level
the
terminator
excavations,
sometimes
be
the
on
clefts.
or
of
of
; in
moon
beautiful,
very
magnificent picture
a
above
The
projection
when
"darkness
the
is also
half
feet
20,000
Imbrium.
Iridum
later.
after
day
a
45
form
neighbourhood,
Mare
Sinus
MOON,
the
the
of
on
a
have
earth's
great
very
tific
scien-
feebly
dull,
coppery-
been
bent
out
atmosphere.
opportunity
stars
of
progress
which
ordinary
may
are
be
too
occasions.
POPULAR
46
almanac
Any
moon
will
be
may
some
When
ation
of Stars.
of
the
it passes
in
front
be
may
the
be
may
for
out
which
the
the
moon
It
the
There
size
would
of
visible
by
a
limb
drawn
been
with
even
with
of
will
for
than
details
made.
new
accompanies
the
have
other
Reference
map,
and
requirements
some
of
to
of
a
vations
obser-
such
of the
times
of
already
be
lead
a
of
power
lunar
80
what
The
the
added
that
to
the
Mr.
those
been
Elger's
which
book
who
the
search
has
sufficientlycomprehensive
as
of
to
reference
the
made
as
charm
observer
if
100.
or
of
scenery
made
well
of
volume
whole
been
as
to
moon
telescope, especially
bear
the
the
on
fraction
mere
which
to
beginners
experience.
look
to
demonstrations
the
aperture.
those
is
map
gives
disappearance
objects
2-inch
a
this
now
may
of
records
of
are
inevitably
has
it
the
the
descriptions
subject, however,
the
on
desiring
value
difficultyin fillinga
telescope
or
brighter stars,
those
of the
good enough
no
eastern
occur
the
the
to
atmosphere.
has
be
of
one
sequence
con-
Almanac
scientific
is
In
the
on
instantaneous
that
be
this
The
occult-
the
eya
will
by
space.
relatively
place
exactness
understood
object-glass
naked
occultations
eclipsing
or
people
Whitaker's
The
moon's
observed
be
take
"
planet,
or
the
consulted
the
occur.
attention
which
the
is without
be
must
star
motion
limb.
of
upon
the
at
that
can
they
stars
the
round
journey
which
stars
reappearances
phenonema.
depends
at
will
conveniently
these
of
with
the
monthly
occulting
"
eastward
while
particulars
its
bright
a
even
right-hand
or
reliable
of
moon's
limb,
western
and
the
In
"
myriads
disappearances
left-hand
of
eclipses
which
on
constantly
observed
of
stars,
is
moon
other
or
dates
expected.
the
earth,
the
give
Occultations
the
ASTRONOMY.
TELESCOPIC
to
meet
already
CHAPTER
VI.
PLANETS.
THE
How
besides
the
larger
earth
than
Venus,
of
the
and
others
The
and
Neptune,
"asteroids,"
near
have
the
since
the
to
and
400
distant
or
of
so
sun,
worlds
small
planets,"
minor
"
or
known
nearest
dim
are
Mercury,
been
being
removed.
them
smaller.
are
Saturn,
bodies
of
some
;
their
in
other
are
dwell
first-named
the
farthest
last
relatively
;
Circling
"
there
sun,
we
and
Jupiter,
times
Uranus
the
planet,
own
Mars,
planets.
which
on
our
pre-historic
and
round
orbits
respective
the
recognise
to
but
modem
are
discoveries.
in
Beginners
the
mere
In
the
first
respect
of
their
to
the
leaving
is
never
rising
by
its
radiance.
all
when
ruddy
and
far
the
they
the
is
When
one
sun,
while
Saturn
become
47
the
Jupiter
again,
by
accustomed
for
sky
some
with
his
that
may
is
tinguished
dis-
are
by
each
fact
the
by
again,
from
so.
ones,
positions
evening
by
Mars,
and
has
their
distinguished
are
setting.
appearance,
closely
the
in
considerations,
from
sun
bodies
not
stars
Jupiter,
and
is
principal
the
watched
change
to
other
from
required
this
the
only
if
Venus
telescopic
very
and
but
planets,
to
apt
are
knowledge
body
a
seen
stars.
brilliancy;
out
as
be
the
consider
we
light,
will
they
from
great
of
distinguished
are
steadiness
nights
if
place,
astronomy
considerable
some
identification
for
they
is
of
study
out-door
there
that
imagine
the
their
other,
Venus
be
even
distinguished
steady
to
the
yellow
use
of
a
there
star
map,
the
planets,
almanac.
a
is
and
only,
can
if the
which
particulars
it lies.
declination
student
The
of
planets
The
observer
must
the
of
will
planets
stars
that
be
star
map,
and
the
be
is
one
of
the
at
to
heavens.
and
rising
bodies.
their
in
movements,
distances
such
if, for
; and
satellites
it must
not^
newly-discovered
fifth
with
seeing
the
connection,
the
within
like
case
the
in
in this
that,
look
will
and
enable
heavenly
in mind
near
will
times
approach
stars
that
imagined
the
stars
20)
useful
very
other
or
bear
should
such
example,
is also
sometimes
the
the
morning
ascension
right
page
on
determine
to
the
giving
the
to
as
corresponding place
the
of the
setting
found
the
in
or
an
whether
indicate
once
evening,
place
Orrery
used
be
may
be
its exact
Philips^ Patent
and
will
at
planets (see
it in
recognise
once
the
table
the
plot
to
in
with
conjunction
in
will
this
seen
difficultyin recognising
any
used
be
map
to
be
to
be
longer
no
Reference
planet
ASTRONOMY,
TELESCOPIC
POPULAR
48
Jupiter,
satellite.
Mercury.
that
this
planet
those
by
This
to
observed
before
its
in
the
at
The
that
three
for
on
and
it is said
parture
de-
maximum
after
sunset
the
or
in
sun
furthest
in
be
side
other
that
so
When
to
be
only
can
precedes
sky.
the
on
it
hours
least
it is at
eastern
it is said
to
elongation.
western
of
revolution
during
times
telescopes.
its
or
the
furthest
when
2
side,
eastern
except
degrees removed,
it follows
as
across
the
mounted
At
28
only
searching
country,
because
but
than
movement
sun
this
brilliancy,as
dawn.
more
sunrise, according
the
of
or
it is
sun
visible
never
elongation,
be
of lack
twilight
the
in
equatorially
first-magnitude star,
a
apparent
from
all
at
seen
with
account
on
from
it is
be
can
careful
after
usually only
is
provided
is not
equal
It
"
a
year
a
the
planet
it is three
"morning
times
star."
of its orbit, however,
round
an
On
it does
the
"
sun
evening
account
not
is
rapid,
so
star
of
always
"
the
reach
and
centricity
ec-
the
distance
angular
same
that
be
it cannot
In
small
from
derived
astronomy
it
owes
for
its
To
these
minutes,
pass
a
transit
of
in front
of the
spot, which,
be
seen
The
or
about
1895.
with
planet
the
June
of
almost
indispensable
or
opera
an
in
will
when
the
planet
visible
of
to
low
as
of
the
'
N.
a
that
diameter,
in
it
us.
the
that
will
of
22^
from
Sun.
12.
Nearly
27"
from
Sun.
189^. Apr.
28.
Nearly
21*"
from
Sun.
Aug.
26.
27"
the
eastern
a
as
naked
eye,
to
circular
can
easily
2J.
as
power
dark
seen
for
observation
on
:
"
Jupiter.
16.
from
is
planet
Sun, in Gemini.
from
Sun,
other
remember
following days
24"
Nearly
the
from
Sep.
to
appears
25**
May
it is nearest
the
situated
favourably
evenings
5.
when
by sunlight. Mercury
Mercury,
not
be
of arc,
and
moon.
telescope
a
3,000 miles,
degree
a
1.
Oct
are
occasions
these
seconds.
sun,
though
half
O'^ 47
There
to
near
means
when
8.
1896.
On
should
one
illuminated
body
the
phases
During
whom
to
sky
the
seconds
5
seconds,
about
like
on
of
is about
from
values,
1,800
or
dark
a
13
to
each
are
moon
planet
varies
diameter
appreciate
Being
put
of the
us,
is, 30
indeed
opera-glass is
from
and
sun
readily by
senger
Mes-
"
alL
part
a
swift
the
be
to
Copernicus,
it at
saw
of
features
no
Mercury.
apparent
is farthest
never
that
perhaps, Jupiter.
or,
diameter
real
The
of
so
elongations.
satisfaction
glimpse
a
for it is said
pretty
field-glass. An
searching
planet presents
planet occupies
found
be
all the
at
certainly great
much,
so
the
times
may
is
Gods,"
planet Venus,
the
this
elongations,
the
at
sun
observed
merely catching
of the
At
the
well
equally
there
but
interest,
from
telescopes
49
PLANETS,
THE
but
rather
low.
Sun.
"
elongations
"
besides
those
TELESCOPIC
POPULAR
60
stated,
low
but
altitude
of
Venus.
revolving
as
of
its
in
noting
sight
and
the
the
sun,
do
not
disc,
planet
small
half
daylight,
a
to
the
a
moon
to
its
us,
show
The
the
the
of
it
time
days
any
is
very
consequence
A
magnifying
crescent
from
is
from
full
of
smallest.
which
are
Occasionally
the
means
will
phase
Venus
in
of
appearance
size
to
our
greatest
removed
naked
sunlight
eye
with
the
pointing
full, a
;
nearly
the
of
varying
its
diameter
apparent
arc.
the
telescope.
seen
that
moon
apparent
visible
For
direction.
or
when
be
2004.
then
the
on
of
conjunction,"
is
full
across
Transit
At
sun,
towards
pass
8,
is farthest
be
to
are
Venus
in
but
phase
few
there
proper
of
it
the
2-inch
easily
may
the
its
a
June
as
line
same
the
"inferior
markings
of
range
to
as
and
planet
delicate
angular
57 seconds
show
while
and
earth,
the
from
presented,
diameter
The
of
from
well
as
is turned
effective.
most
bright enough
in
instrument
this
difficulty
the
happens
until
crescent,
a
be
telescope, if
small
bility
possi-
account
on
size
in
us,
known
distances
the
to
of Venus
again
consequently,
is
it
see
any
little
be
apparent
it
after
as
when
quite beyond
its
side
dark
and
certain
planet
in
nearest
occur
will
occur
are
we
by
never
should
it, unless
not
is
when,
There
the
planet
that
so
sun,
can
there
changes
appears
moon
and
interior
an
unsatisfactory object
very
phenomenon
angular
obviously
in
a
the
a
telescope
apparent
the
star, and
When
before
weeks
the
earth
see
will
; this
some
us,
is
great
the
we
Venus
a
and
phases.
as
sun's
the
the
great brilliancy,but
varying
us,
is
of
consequence
midnight.
Telescopically it
of
Venus
evening
or
it at
see
its
Mercury,
been
planet.
between
morning
a
in
the
Like
"
omitted
have
these
ASTRONOMY,
but
power
same
as
distance
from
11
suffices
to
ranges
of
power
when
20
gibbous,
of
about
sun
is
60
that
is
like
the
required
distinctly.
of
revolution
round
the
longer
than
that
52
POPULAR
It
be
may
than
added
lialf that
Mars
will
1896,
and
well
(Map
to
of the
from
4)
five
heavens
the
readily
With
In
the
and
the
the
December
10,
from
us
in
Taurus
recognisea
it will
be
and
west^
stars, if watched.
i/^
seen
again
for four
be
to
subject
is
which
be
be
seen
on
one
two
on
each
through
eclipsed.
is
the
real
are
a
of
the
side
It
shadow
Sometimes
60
or
of
on
in
our
seeing
belts, and
the
with
belts
large
is
to
seen
highly probable
Jupiter,
of
account
on
in
planet
different
ever-varying aspect,
the
of
the
so
in
but
it
or
is
are
passing
it
it is
when
of
the
satellites
times
other
because
front
they
the
Frequently
on.
planet,
pass
at
periods,
planet's equator,
all
planet,
occulted,
they
the
Sometimes
that
the
of
plane
belts.
reason
of
cloud
seems
of
surface
side, and
therefore
40
observed
the
or
sacrifice
cloud
When
the
an
the
of 80
atmosphere.
from
parallel to
and
disc.
round
present
of
principal
two
his
in
invisible, for
planet,
the
see
removed
far
small
a
difficultyis experienced
no
frequent changes.
satellites
markings,
power
without
power
structure
revolve
they
As
his
satellites
magnifying
the
the
finer
clouds
dense
brightness,
with
principal
Jupiter
with
even
never
we
of
some
observation
to
on
satellites, the
the
size and
of interest.
employed
telescopes,
of
four
his
instrument,
four
of its great
itself
lends
large ellipticity of
be
be
towards
object-glass a
but
home-made
may
will
character
addition,
be
definition,
will
more
is, in
distance
a
1895, onwards,
consequence
2-inch
a
may
never
until
san,
great
east^ then
never-failing source
the
too
at
relatively to
In
"
telescope.
the
the
to
that
opposition,"
"
planet
conspicuous
Jupiter
that
is little
Mars
months.
the
the
be
The
east,
Jupiter.
100
in
be
September,
the
of
earth.
it will
first to
ASTRONOMY.
diameter
the
again
observed.
towards
and
the
not
then
move,
or
that
of
opposite part
be
TELESCOPIC
there
one
may
behind
is
said
the
passing
to
planet,
be
and
THE
instruments
good
with
disc, especiallyif
such
at
times
tracks
dark
a
be
may
their
53
PLANETS.
along
lie
transit
to
seen
is
shadow
the
representing
spot
belts
dark
of the
one
the
across
;
sionally
occa-
observed.
fifth,and
A
of the
any
Lick
small
very
others,
discovered
was
in
telescope
satellite,nearer
but
1892,
Barnard
Prof.
by
is invisible
this
than
Jupiter
to
with
the
but
the
all
in
largest telescopes.
four
The
known
usually
Our
of the
phenomena
be
can
observed
In
this
of the
is
of
1897.
Feb.
23.
he
the
This
when
to
which
on
they
will
observer
find
the
with
sees
remember
of
diameter
the
Jupiter
marking
one
is
scale
about
observe
can
size.
observed
near
constellation
the
In
planet
the
following
Saturn's
ring
succeed
in
is
of
one
the
(Map
3).
Leo
(Map
3).
can
is not
finest
times
Even
a
recognising
least
at
myth,
the
and
the
in
objects
instruments.
observer
"
Cancer
"
adequate
with
seen
telescope, the
may
the
before.
important
"
"
"
of
"
24.
modest
dates
actually
he
smallest
best
the
by
known
:
Jan.
Saitum.
care
the
of
order
particulars
the
years
The
will be
1896.
that
it is
considerable
very
planet
heavens
printed
that
and
what
in
are
Callisto, respectively.
all the
country,
observed.
opposition
our
and
so
for
compare
again,
miles,
really of
The
to
case,
object
80,000
this
also
are
includes
satellites
made
predictions
and
Whitaker
in
interesting
they
Ganymede,
friend
good
but
Galileo
by
proceed
which
numbers,
planet,
lo, Europa,
names
it
the
discovered
Jupiter
their
by
from
distance
of
satellites
with
self
satisfy himwith
principal
a
little
of
features
planet.
A
2-inch
ring.
power
of
30
telescope
With
a
to
appears
will
that
power
of
40
about
be
give
it is
clear
the
minimum
indications
clearly visible, and
on
of
a
the
60-100,
54
with
good
a
line
divides
Cassini's
keen-sighted
on
belts
of
surface
Jupiter
;
the
on
but
must
changes
in
good,
a
distinguish
the
resembling
the
he
has
ceeded
suc-
shadow
cast
text-books
most
to
of
"
remembered
be
that
of
consequence
the
with
compared
be
"
it
very
the
telescope,
familiar
Saturn
should
astronomy
so-called
ring.
of
drawing
A
the
that
states
2-inch
a
to
itself,
planet
dark
the
"
is
able
be
observer
one
with
seeing,
the
parts
definition
also
of
and
two
the
may
the
ball
the
into
When
visible
render
even
ring
observer
in
by
the
division.
belts
will
object-glass,
which
ASTRONOMY.
TELESCOPIC
POPULAR
the
telescopic
of
inclination
the
of
aspect
the
view,
the
ring
of
axis
the
planet.
Of
the
within
from
Like
is
it
only
appears
and
useful
to
but,
Jupiter,
opposition,
near
This
as
the
and
is
owing
star-like
a
Saturn
our
need
remaining
small
be
following
the
best
to
Saturn.
observed
notes
when
of
these
of
interest
dates
beginner.
In
1896,
May
6.
In
1897,
May
17.
In
Libra,
Map
"
planets
instrument,
made.
be
the
as
distance
greater
companion
can
comes
large
as
its
planet,
which
one
nearly
to
.
The
only
"
2-inch.
a
the
is
name
reality,
in
Mars
be
may
of
Mars
us,
by
"
range
planet
it
^Titan
brightest
the
wonderful
this
attending
satellites
eight
so
present
that
no
no
2.
"
features
further
reference
to
in
them
CHAPTER
VII.
COMETS.
Orbits
of
Comets.
No
the
with
examining
objects.
Sometimes
universal
attention,
them
revolve
they
of
some
their
their
in
regular
planets
do
mostly
the
"
this
when
seen
of
the
is
it
that
is,
they
sun
most
are
greatest.
in
short
the
are
of
the
perihelion,
Few
of
attain
peri6ds
brightness.
55
the
for
it
out
nearest
than
sun
then
which
considerable
are
gated;
elon-
orbit
orbit
is
been
orbits
planets,
comets
any
have
much
the
the
much
as
planets
ellipses
of
off
luminary.
our
these
to
pay
pass
The
unlike
comets,
suddenly,
great
point
of
forms
the
ones.
point
ances
appear-
system
our
closer
distant
periodic
near
the
"
much
very
the
reason,
is
are
the
as
"
the
whereas
their
of
that
elliptic
into
"perihelion
to
of
one
that
afterwards
sway
believed
of
paths
they
brightness
round
and
attraction
at
"
aphelion,"
For
belong
now
but
us
and
the
beyond
"
that
sun
speak,
them.
shown
make
upon
ful
power-
upon
having
come
to
most
sun,
thus
orbits
These
far
eccentric
very
so
in
so
the
of
many
have
round
and
while
bear
to
attract
to
the
movements
move
comets
parabolic
their
to
the
by
brought
orbits
sun,
;
in
ellipses,
space,
the
diverted
of
of
of
some
the
as
the
depths
Hence
in
others
to
respects
difficulty
of
lost
remarkable
enough
1882,
apparent
be
these
and
be
hyperbolas.
or
the
into
1858
with
of
regularly,
parabolas
bright
are
can
travel
them
they
in
which
instruments
Observations
any
perceived
only
are
of
telescope
as
should
opportunity
"
is
called.
are
that
at
only
their
revolve
degree
Where
in
seeing
case
of
them
can
three
and
four
or
its
be
such
Mechanic,
"c.,
will
The
The
a
tail
no
when
When
be
at
The
be
at
The
"
only
as
even
its
will
of
is
a
star-like
somewhat
this
opportunity
The
more
point
is half
the
in
the
the
the
structures
will
of
no
observing
numerous
the
"
coma,
of
map,
and
comet
is to
of
some
have
a
of interest
have
comets
small,
are
called
centre
by
of
them
of
into
of
or
head
and
times
some-
"
detail.
interesting
a
an
of luminous
prove
class
star
is, undoubtedly,
of which
layers
project
doubt
readily
comets
Sometimes,
surrounded
fan-like
and
position
be
This
of
amount
the
nucleus
phenomena
comet
resembling
times, jets or
the
a
and
telescope.
considerable
a
sometimes
from
of
a
and
particular hour.
any
tail
tails,some
of
aid
brightest part
shows
There
the
6
;
determined.
once
tail.
a
the
telescope.
as
many
with
seen
The
the
English
Ascension
sky
many
present,
from
popular impression
with
but
cordingly,
Ac-
daily papers
map,
place
of the
path,
comet
a
comet
in
to
star
a
star
the
on
observation,
a
on
part
Comet.
a
of
time
if used
large comets,
with
seen
or
and
of
Right
will
stars
what
it is like
all.
at
the
happen
may
its
striking feature, though presenting nothing
most
two
of
true
in
of
is that
extent
for
comet
of
map
predicted.
of the
the
bright enough,
stars
parts
comet
of
for
observed
been
be
then
can
occasionally some
indicate
surrounding
has
star
a
Observatory^ Nature^
Planisphere,
further
cases
"ephemeris"
The
the
directions
possible to compute
dates
an
evidently only
is
any
such
comet
a
particulars
if
way,
found.
that
in
becomes
surrounding
to
It
"
corresponding place
the
relation
this
When
even
or
of
by finding
In
and
as
furnish
will
Declination
in
needed,
obtains
source
this
comets
future
on
one
some
fainter
the
nights, it
place
Comets.
for
is essential.
sort
some
look
to
the
ASTRONOMY.
TELESCOPIC
POPULAR
66
the
great
the
nucleus,
series
of
envelopes
onion
;
at
other
proceed
matter
All
coma.
interest
when
such
the
occurs.
small
comets
do
not
exhibit
COMETS.
such
of
their
Continued
of
formation
the
the
Not
continue
of
its
shine
to
Movement.
rapid
that
suffice
to
the
even
show
field
for
this
from
the
is, in fact,
position
of
often
the
The
of
to
of
; and
discover
a
of its character
of
Retiims
the
it
relation
distinguishing
comet,
this
observer
he
Ascension
great
on
stars.
finding
the
of
accuracy,
the
meridian
which
:
be
nishes
fur-
stars
the
himself
Among
be
may
nebulae
fortunate
quite
Comet.
Period
7J years.
7
"
"
"
"
"
"
D'Arrest's
Swift's
"
6i
5i
the
expected
"
Brooks's
1897.
should
make
can
the
it from
Comets."
comets
Faye*8
to
tain
cer-
feature.
Periodic
following
1896.
in
if the
by
interesting periodic
are
of
in
mined
deter-
comparison
way
observe
to
is
with
requisite degree
comet
a
means
star-clusters
enough
of the
be
instrument.
movement
ready
the
Right
will
intervals
at
determined
only possible
the
impossible
transit
a
be
to
position
the
so
regard
happen
noted
relative
can
with
comet
be
positions
with
it is sometimes
with
comet
frequently
telescope
a
may
measurements,
known
comet
a
which
this
of the
Declination
This
and
When
raicrometric
the
should
time
is
with
of
position
same
purpose.
accuracy,
as
the
at
it
behind
situated
of comets
stars
the
is
lustre.
observation
conspicuous
by
and
The
it.
the
of
comet
a
stars
;
movement
hour's
an
about
undiminished
The
gradual
the
sun.
thing
parts
of
patches
intensification
the
to
various
with
"
more
the
approach
stages
some
reveal
may
the
remarkable
least
transparency
tail, and
at
faint
as
appear
watching
short
a
during
nucleus
telescopic details, and
they simply
careers
luminosity.
to
of
great variety
67
"
"
more
to
appear
re-
1898.
ASTRONOMY.
TELESCOPIC
POPULAR
68
Winiiecke's
Period
Comet.
5i
Wolf's
7
"
1899.
"
13|
"
found
complete
in
"
Halley's
76
"
"
A
"
Tuttle's
"
1911.
years.
of
history
Remarkable
and
these
Comets^
a
other
little
Lynn.*
*
Stanford,
price
"
6d.
book
comets
by
Mr.
will
be
W.
T.
POPULAR
60
of
the
sixth
; but
to
carry
of
the
brighter
than
of the
star
a
as
in
100
to
that
round
less
8th
of
2-incll.
should
of the
universe
of stars
in
apparent
collects
and
the
equal
the
of
this
light
show
stars
and
its
area
greatly
the
on
were
as
eye
2-inch
is
light
as
limit.
reflection
in
nitude
mag-
power
because
the
the
the
the
only
will
O.G.
be
100
on
11th
mag.
Owing
to
the
"
the
our
ideas
proportion.
become
eye
object-glass
of
the
is
the
by
pupil
the
to
be
i.e.,5
loss
this
mags,
of
lenses, however,
one-
that
pupil, so
of
of
area
light
more
eye,
nearly
one-hundredth
times
than
and
instrument
of the
diameter
we
existence
pupil
object-glass divided
with
the
of
naked
than
of
out
really utilised, a telescope
faint
of
the
all to
at
object-glass. Hence,
falls
naked
take
we
inch,
star
the
If
an
2-inch
of the
area
pupil.
fifth
a
the
the
invented,
been
ignorance
This
of
amount
also
are
seen
heavenly bodies,
visible
not
7th
is reckoned
example,
Stars
never
been
have
light-grasping
to
had
the
telescopes.
larger
a
of
would
for
of
total
in
great majority
found
be
magnitude
a
have,
ment
measure-
7*5.
telescopes
of the
Millions
amounts
star
a
bright, it
less
Number
remained
have
if
understood
star, it is rated
mag.
of
may
as
and
If
"
we
stated
star
6th
a
if
that
so
Fractions
that
so
Magnitudes
a
bright
as
in the
employed
now
2-5) times
x
on.
so
of,
a
than
(i.e.,2*5
count
are
magnitudes,
and
mag.,
taken
precision
bright
if 6*25
;
mag.
of
stellar
times
2^
of
star
a
itself 5 times
multiplied by
times
100
times
be
will
sary
neces-
average
that
so
2^
really about
This
the
reckoned
;
is
is
numbers.
Instruments
of
2-5
that
magnitude
fainter.
magnitude
one
considered
it be
is
found
fairlybe
sixth
notation
telescopes,it
been
may
particular magnitude
any
has
this
it goes,
as
have
we
It
magnitude
one
far
that
now
it further.
first
ASTRONOMY.
So
magnitude.
still retained
star
TELESCOPIC
that
size
lower
of
from
a
if all
would
than
light by absorption
the
minimum
THE
visible
magnitude
With
nights.
In
the
well
as
of
2-inch
little
interest
with
in
In
on
a
numberless,
and
adds
charm
the
to
that
out
the
the
and
Auriga, Sagitta, Aquila,
cited
be
may
When
of
view, they
are
Ooloured
colours,
stars
of
and
j8 Pegasi,
once
enable
a
Cor.
these
little
telescope.
identified
to
patience
:
the
will
colour
be
pointed
is
specially
Cygnus,
of
a
in
the
Persei
The
deep
required
in
which
brighter
Aldebaran,
will
maps
red
desired
if it be
be
the
to
field
for their
the
Among
remarkable
more
stars
to
are
observe
pointing
be
can
at
the
easily
"
H
Cephei
Mira
^
a
Variable
that
almost
and
remarkable
are
Reference
so
sky
(Chap. X.)
clusters
star
as
recognised.
radiance,
more
Way
Betelgeux, Antares,
are
be
may
together
yellow.
or
of
regions.
stars
Hydrse.
Among
are
red
tint
of feeble
mostly
these,
chiefly
reddish
Many
"
met
the
are
neighbourhood
closelygrouped
very
stars.
deep
the
of
constellations
the
distinguished
are
Milky
be
worthy
brightnesses
the
particularly rich
as
stars
a
of
of
be
to
groups
It
as
range
may
parts
them.
observing
respect, and
this
in
interesting
in
these,
conditions.
well
some
over
the
frequently
telescope, such
neighbourhood
all
stars
groupings
14.
are
within
come
are
great variety
of
there
and
9*5,
through
the
with
alone
clear
very
10-inch
atmospheric
or
"sweeping"
on
a
individually the
streams
good night
10*5
with
should
ones,
telescopically,they
beautiful
scrutiny.
and
12*9,
magnitude
Although
"
is about
favourable
glass under
fields.
61
hemisphere
above
or
still fainter
many
Star
it is
celestial
of
stars
2-inch
a
6-inch
a
northern
300,000
a
with
STARS.
stars.
periodic
fluctuations
variation
is not
very
"
Ceti
(Map
1).
(
4).
Virginis (
Herculis
of
Some
in
(
"
"
"
3).
2).
the
brilliancy ;
great,
and
occurs
stars
in
in
are
subject
some
periods
cases
measured
to
the
POPULAR
62
days
by
The
hours
and
the
and
greater,
interest.
glass
in
as
"
naked
telescope
less
the
be
can
few
a
the
the
variables,
star
j8 Lyrse (Map
it has
time
and
in
from
(Map
4)
months),
and
will
the
during
magnitude
equal
to
six-hundred-fold
difficultyin
magnitude,
of
few
years.
2nd
of
afterwards
regularly
until
somewhat
irregular, but
its
monthly
in
Companion
to
other
surrounding
stars.
days,
its
maxima
of
cycle
and
during
minimum
3*5, a
variable
this
of
4*9,
reckoned
for
observation
From
about
at
9th
11
mum
maxi-
10th
or
occasionally
star
star, corresponding
There
progress
be
may
passed.
may
will
it reaches
when
is
(about
star
light.
star
maximum
in
which
continuous
a
magnitude
the
nitude
mag-
of
wonderful
this
of
another.
placed
well
the
with
13
long-period
a
remains
minima
the
3*9, the period being
to
increase
the
fication
identi-
4th
to
observation
magnitude
minimum
identifying
and
the
intervals
at
falls
from
the
under
of
be
a
in
light
published
through
minimum,
at
ever,
how-
original brightness
of
are
as
little
a
next
its
compared
goes
is
Mira
a
be
principal
one
becomes
must
minimum
secondary
a
this,
the
except
it
obtained
be
maxima
two
regains
In
2)
4)
when
observed
may
period
a
to
that
so
difficultyof
the
Particulars
conveniently
they
magnitude,
and
1
days,
time.
or
field
a
invisible
become
magnitude,
and
hours,
Observatory,
changes
2nd
three
same
Knowledge^
6th
or
of
increased.
at
than
or
opera
longer period variables,
Algol (Maps
constant
in
nearly
of
case
full
period variables,
an
never
essential,and
is
enormously
near
little
a
5th
a
the
very
above
rise
is
In
of the
short
must
is
period,
most,
stars
Many
eye.
at
or,
"
the
cases
never
of
aid
required
which
phenomena,
of the
is
months.
considerable
a
variation
of
range
by
of
class
of many
case
these
the
is measured
over
is
ASTRONOMY.
others
of this
the
instrument
the
period
extend
In
in
;
observation
necessarily
no
TELESCOPIC
The
fairly be
to
be
the
no
6 th
observed
period
expected
is
in
STABS,
THE
January
and
in
nearly
very
distance
d
from
Full
line
a
from
the
as
instructions
with
stars,
will
of
New
8
of
the
variable
of
knowledge
the
monthly,
ations,
vari-
Popular
1895.
February,
the
is
nearly
at
observation
American
times
At
It
them.
our
the
in
1897.
Ceti,
between
systematic
and
StaiTS.
through
increasing
January
Astronomy,
a
the
found
be
November,
distance
for
view
a
and
1896,
December,
63
world
astronomical
receives
"
a
fresh
star
new
or
star
no
by
of
source
are
very
only
can
of
possessor
observing
is
worth
powerful
good
star
if
decline
in
that
Nova
map,
of
new
form
stars.
an
nearly
it.
all
Usually
they
feeble
so
instruments.
gratification
some
fortunately
become
fluctuations
irregular
and
brilliancy.
the
last
pocket
of
new
1892
with
telescope.
outfit
no
the
more
Obviously,
of
of
in
discovered
was
"
knowledge
the
visible
star
Anderson,
extended
part
where
discovered
been
become
find
should
Dr.
a
place
a
powerful
will
Aurigse,
than
and
weeks
most
one
its
"
instrument
the
the
noting
to
so-called
a
immediately
few
a
telescope
astronomer,
must
discoverer
in
remarking
amateur
an
seen
star
hemisphere
northern
in
has
directed
are
and
small
in
rapid
subsequent
be
new
a
especially
visible,
by
a
and
in
star,
a
exist,
to
world
of
appearance
like
observer,
the
in
the
known
short-lived,
they
It
looks
painstaking
telescopes
in
What
previously
the
The
in
nova.
was
some
that
interest
the
the
would-be
a
stellations,
con-
CHAPTER
IX.
DOUBLE
Doubles
and
STABS.
Binaries.
It
often
which
of
single
appear
close
two
These
there
stars
side,
although,
appear
widely
their
that
changes
stars,
or
to
Stars
reference
has
Though
the
the
Some
others
the
colours
companion
will
forming
of
In
nearly
a
many
equal
usually
are
is
in
will
the
two
movement
called
are
doubles,
much
themselves
stars
evident
apart
quadruple.
are
planets
binary
which
to
made.
it is
stars
of
orbital
optical
the
law
between
class
latter
the
by
really
observations
that
so
be
same
of
distance
from
component
wider
the
of
would
they
may
by
two
side
appear
suns
continued
them,
that
line
same
space,
movements
the
them
been
enlargement,
power,
of
distinguish
two
apparent
joining
the
of
part
stars,
the
line
indicated.
stars,
of
in
the
in
such
clear
is
First,
they
together
the
it
in
that
so
Next,
controls
telescope.
a
appearances.
another
bound
and
nearly
earth,
from
in
courses;
show
is
the
and
such
very
separated.
together,
gravitation
be
with
stars,
for
to
seen
observed
stars
consist
to
seen
are
eye
double
causes
from
seen
as
close
two
happen
may
sight
so-called
be
may
naked
when
components
the
are
the
to
that
happens
"
that
the
the
higher
stars
gravitational
of
magnitudes,
pretty
smaller
than
64
magnifying
the
system
double
the
the
in
appear
similar.
the
telescope.
triple;
are
stars
and
capable
not
are
in
In
primary,
the
such
others
and
ponents
com-
cases
the
very
DOUBLE
frequently has
white
bluish
a
Double-star
telescopes, and
reference.
Castor
of
however,
from
the
in
with
an
In
distance
of
of
in
earth
to
it has
the
stars
from
in
a
two
miles
measured
than
binary star,
the
of
measure
series
that
the
sun
between
two
a
circle
of
too
their
be
have
been
it
not
is
a
the
the
made
likely
themselves
with
content
to
stars
from
far
removed
distance
an
mean
the
components
radius
a
from
the
Thus
us.
times
angular separation
of the
be
the
angular
million
a
foreshortening,
to
calculate
from
is about
measures
is found
the
two
; the
components,
on
to
with
provide
possible
Castor
for
of micrometric
it is
not
are
corrected
when
pressed
ex-
involves
aperture,
would
is
correspond
measurements
to
tance
dis-
size.
they
a
double
a
connection
in
prepared
are
determined
been
distant
more
the
permit
selected
apparent
measurement
inches
two
between
if
measurement,
3,600
micrometer
a
miles
which
of
few
a
who
of this
case
these
symbol
are
The
"
form
micrometer
although
expensive
the
of
arc,
of
of those
instrument
the
simplify matters,
which
stars
process
form
many
and
the
chapter
in this
components.
of
instruments
that
that
To
and
Usually
quoted,
are
them.
to
known
best
astronomers
to
conveniently
objects.
Burnham
of
double.
are
are
the
suitable
purposes
Majoris
of
such
among
The
single degree.
with
reference,
and
two
seconds
telescope,but
for
of
referred
the
some
with
suffice
some
already
stars
seen
term
of
between
between
of
be
stars.
eye
Distance
when
Ursse
catalogues
known
the
Y
in
doubles
naked
use
principal star
and
sufficientlyrefer
^
or
a
of
names
numbers
Struve
generally
so
such
their
by
double
ordinary
having
not
catalogues
2
the
complete
are
the
Many
"
be
to
Thus
indicated
most
whether
colour,
names.
found
are
Others,
65
yellow.
or
named
STABS.
l"*b
distance
is the
million
determined
as
; then
of
between
the
distance
length
times
of
the
7''*5
sun's
POPULAR
66
distance.
sun's
This
will
distance.
about
of
the
To
"
the
follows
:
times
38
nearly
revolution
double
a
this
in
the
is
case
The
central
and
W.,
The
one.
in
as
is
of
the
as
the
expressed
north
the
brighter
position angles
astronomical
an
necessary
from
the
tion
disposi-
measure
a
direction
and
E., S.,
is
angle
the
specify
star,
them
joining
them.
360",
to
be
completely
of
line
through
0"
from
of
angle," i.e., the
measured
as
to
years.
between
"position
taken
found
components
of
direction
ASTRONOMY.
period
angles.
the
distance
be
The
thousand
a
Position
as
TELESCOPIC
by
point
being
star
reckoned
are
telescope they
are
"
S
W^/ol
Fig. 12.
As
line
in
the
with
direction
be
careful
E.
of the
of the
movement
must
the
to
and
W.
across
the
confuse
this
star
not
a
in
the
faint, as
telescope
the
is
usually
two
the
is
useful
is not
eye
in
cases
wearied
direction.
wrong
of 2-inch
power
between
position angle
is very
searching
Dividing
distance
of
companion
the
of
the
horizontal.
needless
power
sun,
apparent
beginner
knowledge
where
by
the
the
A
of the
of the
is that
field,and
case
Illustrating position angle.
"
telescope.
stated
components
in terms
of
the
"
The
dividing
of the
angular
closest
double
POPULAR
C8
in
striking
of
TELESCOPIC
small
a
ASTRONOMY,
but
telescope,
included
are
for
sake
the
completeness.
The
column
idea
some
of
observe
the
provided
with
30
the
when
while
lowest
field
lens
used
be
in
gives
regard
various
numbers
The
recent
rapid
notes
in
as
be
rate.
60.
well
as
position
in
changing,
the
case
though
of
Judgment
must
the
as
a
rule,
be
remarks
by
maps,
the
distance
binaries
worth
also
the
of
of
or
can
of
to
and
not,
be
column
only
20,
indicates
situations
angle
of
scarcely
references
the
be
column
The
indicating
of
sources,
of
to
expect
may
power
a
will
this
weather.
as
brackets,
measures
obviously
the
to
it
observer
instrument
him
removed,
power
a
he
the
giving
which
those
with
seen
is
which
if
;
eye-piece,
one
attempting
only
double
the
give
to
with
power
particular
any
intended
is
"power"
stars.
from
are
values
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must
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visible
in
the
will
each
in
made
in
in
show
II.
the
the
71
month."
double
corresponding
preceding
working
The
foregoing
numbers
the
preparing
Chapter
of
the
of
each
in
which
month,
column
first
assistance
is
visible
stars
table
ing
STARS,
list.
lists
to
follow-
stars
with
This
which
will
are
those
be
reference
of
CHAPTER
CLUSTERS
STAB
Naked
is
it
closely
very
familiar
there
with
is
The
the
that
the
perhaps
of
one
of
the
stellar
one
when
viewed
in
even
behold
Gala.xy.
Milky
Way
the
the
it.
other
in
occur
it
eye
"fire
In
is
air
is
of
defiled
not
features
of
as
the
but
with
smoke,
the
evening
nebulous
filmy
a
old
small
the
of
distribution
these
stars
much
greater
naked
stars
but
astronomers
the
distances
is
form
of
corresponds
eye,
of
it
the
9th
to
the
those
magnitude.
72
which
of
consist
a
According
the
Milky
"Way,
closely
very
comparatively
than
to
seen
enumeration.
defying
stars
probably
are
aid
optical
investigations,
to
it
towns
advantage,
to
seen
appears
mist"
large
our
"
striking
most
smallest
of
recent
an
"
the
multitude
this
each
"
with
of
of
or
who
very
from
group
conspicuous,
or
naked
the
To
appears
all
a
stars
part
instrument,
less
is
distant
this
impress
where
country,
open
luminosity
scale
Way
rarely
the
of
small
but
brighter
form
they
aspect
to
example,
sky.
Milky
sky.
to
fail
cannot
the
the
themselves
group
for
of
parts
to
immensely
that
our
groupings,
of
but
be
on
certain
tend
though
doubt
20
In
"
Pleiades,
even
must
little
NEBULJE.
stars
magnificent
glass,
parts
even
and
of
Similar
is
The
power
a
opera
it
together.
The
system.
in
that
group
other,
is
observed
instance,
well-known
AND
groupings.
eye
heavens
X.
15th
the
with
and
magnitude,
small
ones
are
higher
it
as
at
in
not
the
The
of
sweeping
observing
the
afford
student
the'
food
besides,
the
Sidereal
be,
may
reflection
of the
may
there
are
of
them
of
nearly
the
often
exhibit
the
globular
In
of
system
much
close
"
A
table, with
the
the
and
very
with
be described
many
stars
are
close
gether,
to-
large
very
consisting
as
clusters
compressed
very
clusters
hence
are
in
shows
these
wards
to-
known
as
selection
looking
upon
have
been
they
as
part of the
a
sidereal
belongs.
sun
they only
form
to
regularity.
are
abandoned,
probability
clusters
some
we
and
compact,
so
marked
no
clusters
almost
star
quite
not
are
stars
now
our
of these
telescope,but
very
is
which
to
Many
such
in
that
universes
with
shown
order,
globular form, condensing
less
clusters
the
cases
idea
old
distant
cluster, but
these
seen
Milky
clusters.
other
The
when
only
can
or
In
brightness,
These
and
centre,
distribution
the
of
cluster
more
a
this
to
the
different
itself.
Way
"star-dust."
much
depth
system
star
somewhat
close, even
so
the
and
view
immense
an
a
order
same
telescopes, that
so
of
Milky
the
in
as
of
point
one
upon
sometimes
of
From
"
clusters
many
solar
our
of
stars.
looked
be
of
now
Construction
"
length, breadth,
its
relation
is the
what
Clusters.
Way
what
give him,
great problems
the
"
will
tracings,
pleasure, and
of the
one
on
of astronomers
minds
larger system
of
Way,
Milky
stellar
the
amount
73
the
across
in
variety
Universe,"
and
Star
telescope
vast
a
for
the
occupying
the
infinite
NEBULAS.
AND
CLUSTERS
STAB
cases
"
of
particulars
where
as
appear
clusters
as
within
come
to
when
of
star
the
reach
given
and
patches
the
in
where
a
2-inch
stars
component
unresolved
is
of
are
of luminosity.
appended
they
are
to
be
seen.
The
drawn
of
to
the
earliest
up
more
employ
catalogue
by Messier,
and
conspicuous
the
numbers
since
of
in
clusters
this
these
Messier's
and
naturally
objects, it
nebulae
includes
is still
catalogue
for
was
most
common
purposes
of
reference.
in
"
of
is
in
the
Messier's
catalogue
eye
given
the
general,
Most
on
"
a
of
very
will
low
the
best
named
clusters
clear
facilitate
20
as
nights,
the
these
on
search
not
included
numbers
in
and
nebulae,
objects
will
2-inch
our
revision
a
it
is
hoped
for
be
them.
obtained
telescope.
visible
dimly
are
and
that
Dreyer.
of
views
cluster
and
their
by
clusters
Dr.
by
power,
of
the
Clusters
designated
are
that
catalogue,
Pegasus.
catalogue,
using
Messier's
in
Catalogue
Herschel's
In
15
indicates
Pegasi
constellation
General
New
by
No.
ASTRONOMY.
M.
15
Thus,
question
occurs
in
TELESCOPIC
POPULAR
74
that
to
the
the
naked
directions
it
the
POPULAR
76
NebulSB.
TELESCOPIC
It will
"
star
clusters, when
dim
patches
of
sufficient
power
imagined
that
of
into
shows
the
require further
nebulae
impressed
Canes, which,
in
nebula
a
a
naked
scrutinised
the
second
The
others
and
the
Faint
to
his
are
observe
one
still very
many
Hence,
This
from
whether
clusters
and
difficultywill
of
comparison
bright enough
few
with
such
a
like
one
the
on
ance
appear-
which
visible
be
to
be
can
Nevertheless
will
this
with
profitably
the
telescopicdifference
the
student
between
form
a
valuable
a
be
little
image
time
rewarded
not
see
at
moves
centred,
once
and
a
by
to
before
found
a
little
the
everything
the
the
keep
looking
if
the
moderate
in
appearance
the
beginner,
eyes
for
from
them.
telescope
rate
patience
at
first
easily observed.
most
difficultyto
taken
readily
more
following list,the
the
little
some
should
some
in
to
important
most
the
does
troscope
spec-
which
said
be
telescope,puts
very
referred
be
The
distinct
can
be
cannot
reading.
are
will
ance
appear-
quite
it
telescope.
present
when
they
easilyresolved,
cluster, and
the
may
that
so
;
are
precaution
field,and
details
star
nebulae
moved
to
a
lights for
strong
are
a
strated,
demon-
the
on
the
comet.
are
observe
nebulae
and
small
2-inch
a
himself
supplement
Of
there
is
2-inch
a
nebulae
with
and
nebula
or
two
eye,
for
be
to
after
observer
simply
was
distinguish
that
clusters.
Praesepe,which
Although
may
the
on
were
whatsoever.
before
star
or
and
there
investigation
the
as
of
the
time
same
it
abundantly
usually catalogued together.
are
cluster
them
time
"
to
been
power
any
of
really nebulae
are
3
with
one
nebulae
"
of
telescopes
nebulae, putting
true
many
At
clusters.
has
really exist,
stars
At
as
appear
resolvability,
with
unable
were
It
do
resolved
termed
we
compressed
of
signs
no
them.
now
that
telescopes,will
or
be
with
are
that
clouds,
resolved
M.
deal
which
however,
be
easily
to
in
small
little
light with
constituents.
separate
they
with
seen
what
clusters
star
easily understood
be
although they might
ASTRONOMY,
first
across
be
the
continuing
of
greater
glance.
STAB
CLUSTERS
AND
NEBULJE,
77
Ymmm
m
2yi
inch
I
*i.^
diameter,
"
""
""
3*
*4.
"
,,
""
"
for
eye-piece.
'
'
2.
DBSCMBED
Glass.
Object
Achromatic
focus
Lens
3
AS
nm.
inch
30
I
,,
TELESGOFB
UP
HAEINEf
FOE
MATERIALS
I
I
a
"
""
""
Thin
a
Disc,
Brass
eye-piece.
extra
,,
""
""
inch
i
for
Lens
J
"
,,
""
""
""
""
hole
with
diameter,
|
for
diameter
inch
eye-piece.
5.
Thin
Brass
Disc,
inch
i
with
diameter,
hole
for
diameter
inch
J
eye-piece.
extra
^
*6.
Mache
Paper
Tube,
inches
24
long
Blacked
diameter.
inches
2}
and
inside.
*7.
of
Set
tube.
draw
t8.
9.
Set
of
Dark
1 1.
Screen
Ink
Glass
for
Complete
for
the
viewing
of
tubes
making
glass
cell,
and
Sun's
the
with
parts,
named.
last
brush.
directly.
sun
without
Telescope
object
eye-piece,
internal
blacking
Projection
for
inside.
Rollers
for
for
Tubes
Blacked
Wooden
4
Bottle
10.
12.
of
Mache
Paper
5
image.
Stand,
eye-piece
one
magnifying
times.
13.
Extra
14.
Tripod
Eye-piece,
Telescope
made
15.
Extra
magnifying
of
piece
Stand,
attaching
*
Parts
t Alternative
to
and
for
No.
to
top
making
7.
horizontal
(for garden
finished
Holder
essential
times.
vertical
with
well
beechwood,
for
40
of
Window
Telescope,
use).
Sash.
adjustment,
20
I
V-
To
avcMd
or
'oECiaw
Si'
""1'*"'''
w^
fine, thii
before
the
book
date
should
last
be returned
stamped
below
on