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the heavens
revealed
Classics of Astronomy from
Ptolemy to Copernicus to Einstein
from the Collection of
Professor Jay M. Pasachoff
CHAPIN LIBRARY · WILLIAMS COLLEGE
MAY- SEPTEMBER 2003
Jay M. Pasachoff has taught astronomy and astrophysics at
Williams College since . His special research interests are
the study of the sun at total solar eclipses, cosmic deuterium
and its relation to cosmology, and the atmosphere of Pluto,
as well as the history and art of his discipline. He has written
many books and articles, including A Field Guide to the Stars
and Planets for the Peterson Field Guide Series; Astronomy:
From the Earth to the Universe; Fire in the Sky: Comets and
Meteors, the Decisive Centuries in British Art and Science (with
Roberta J.M. Olson); and The Cosmos: Astronomy in the New
Millennium (with Alexei Filippenko).  The star maps shown
in the hall display case were drawn by Wil Tirion for A Field
Guide to the Stars and Planets. The painting of the constellation Taurus on display in the Library gallery is by local artist
Robin Brickman.  Professor Pasachoff ’s important personal
collection of rare books related to astronomy and astrophysics
is on deposit in the Chapin Library, where it is used in concert
with the Library’s esteemed History of Science collection to
further the educational program at Williams.
Woodcut initial P from Ptolemy, Almagest, 1515
(Collection of Jay M. Pasachoff)
Bible. Latin.
Mainz: Johann Gutenberg, [ca. ]
Collection of Jay M. Pasachoff
of the universe, and the sun, moon, planets, and
stars revolve around it in circular paths on concentric
spheres – as shown in the exhibition by a woodcut in
Peter Apian’s  introduction to cosmography.
The so-called Alfonsine Tables, of which a copy of
the first printed edition is in the Pasachoff collection,
were compiled at Toledo in Spain at the request of
Alfonso X “the Wise” of Leon and Castile. Their starting point is  May , the eve of the king’s coronation. Based on Ptolemy’s nd-century Almagest with
certain mathematical refinements, and following the
general format of tables by the th-century Cordoban
astronomer al-Zarqali, the Alfonsine Tables permitted
the user to determine the position of the sun, moon,
planets, and stars at any given time or place, and to
predict eclipses and conjunctions. Such ephemerides
were used primarily by astrologers, but were also
an aid to navigation.
It is only fitting, in an exhibition which celebrates
the study of the heavens and earth in rare printings,
also to display part of the holy word of the Creator
from the earliest printed Bible. This leaf from
Gutenberg’s famous -line Bible contains part
of the text of  Chronicles from : to :, which
describes the building of the Temple of Solomon.
Jakob Pflaum, ca. –
Calendarium
Ulm: Johannes Zainer, 
Collection of Jay M. Pasachoff
Regiomontanus, –
Calendarium
Venice: Bernhard Maler (Pictor), Erhard Ratdolt,
Peter Löslein, 
Gift of Alfred C. Chapin, Class of 
Pflaum’s Calendarium is one of the earliest calendars
published in book form, providing essential astronomical tables valid from  to , and lists of predicted
solar and lunar eclipses from  to . It is displayed
next to an illustrious predecessor, the Calendarium by
Regiomontanus published at Ulm in .
Peter Apian, –
Cosmographicus Liber
Landshut: Johann Weyssenburger, 
Gift of Alfred C. Chapin, Class of 
Hartman Schedel, –
Leaf from Liber Chronicarum
Nuremberg: Anton Koberger, 
Collection of Jay M. Pasachoff
Alfonso X, “el Sabio”, King of Castile
and Leon, –
Tabulae Astronomicae Alfontii Regis Castellae
Venice: Erhard Ratdolt, 
Collection of Jay M. Pasachoff
The Nuremberg Chronicle is a history of the world
from Creation to the year of the book’s publication.
Produced as a monument to the greatness of Nuremberg, it is one of the most thoroughly designed and
lavishly illustrated books of the th century. Both
Latin and German editions were published in .
In addition to its importance in trade and printing,
Nuremberg was a center of mathematical and astronomical studies, and for the production of celestial
The nd-century Alexandrian astronomer Claudius
Ptolemy described what came to be known as the
Ptolemaic system, in which the earth is at the center

Claudius Ptolemy, nd Century
Almagestum Cl. Ptolemei
Venice: Petrus Liechtenstein,  January 
and terrestrial globes. It is fitting, therefore, that
several astronomical instruments, and a portrait
of the astronomer Regiomontanus, appear in
the Chronicle. The book also notes, with pictures,
thirteen appearances of comets from  to .
 :
Georg Peurbach, –
Tabulae Eclypsium Magistri Georgii Peurbachii
Regiomontanus, –
Epytoma in Almagestum Ptolemaei
Venice: Johannes Hamman,  August 
Gift of Alfred C. Chapin, Class of 
Johannes Regiomontanus, –
Tabula Primi Mobilis Joannes de Monte Regio
Edited by Georg Tanstetter
Vienna: Johannes Winterburger, 
Ptolemy’s explanation of how the universe works held
sway for some fourteen hundred years. It was based on
the common-sense view that the sun, planets, and stars,
as well as the moon, revolve around the earth, as they
appear to do as one sees them in the sky, and it proclaimed the perfection of the heavens by describing
motion in circular paths and on concentric spheres.
To account for the movement of the planets, however,
which sometimes appear to double back in their
courses, Ptolemy had to suppose (to put it simply)
that each followed a smaller circle (epicycle) while also
moving on a larger circle (deferent) and turning with
the associated sphere. Although a complicated system,
it allowed for astronomical and astrological predictions, as shown by the Alfonsine Tables.
The Islamic world, with its penchant for measurement, gladly received and preserved Ptolemy’s mathematical analysis of celestial motion, which came to
be known as the Almagest or “greatest work”. Its first
appearance in print was as the Epitome begun by the
Austrian astronomer Georg Peurbach and completed
by his pupil Johannes Müller of Regensburg, called
Regiomontanus. It is not merely an abridgment of
Ptolemy but includes later observations, revised
computations, and critical reflections. (By this time,
in fact, its deficiencies were known to scholars such
as Peurbach and Regiomontanus, who held to higher
standards of accuracy in celestial computation.) Its
frontispiece shows Regiomontanus sitting next to
a crowned Ptolemy beneath an armillary sphere.
Collection of Jay M. Pasachoff
In Professor Pasachoff’s collection is a copy of the first
printed edition of the complete Almagest, translated
into Latin by Gerard of Cremona in the th century
from a translation into Arabic, made in turn from the
original Greek. In addition to its explanation of celestial movement, it includes a star catalogue based on
Hipparchus and descriptions of instruments for use
in astronomical observations. The Pasachoff copy is
in a contemporary stamped pigskin binding with
original clasps.
Here Ptolemy’s work is bound with the first printing of the Tabulae Eclypsium or tables of solar and
lunar eclipses by Peurbach, completed probably in
, based on the Alfonsine Tables but expanded,
rearranged, and altogether improved; and the Tabula
Primi Mobilis (“Table of the First Movable Sphere”)
by Regiomontanus, which describes the apparent
daily rotation of the heavens.
Nicolaus Copernicus, –
De Revolutionibus Orbium Coelestium
Nuremberg: Johannes Petreius, 
Two copies shown: Collection of Jay M. Pasachoff;
Gift of Alfred C. Chapin, Class of 
Copernicus, a canon of Frombork in Poland, pursued
an interest in astronomy which was ultimately to
overthrow the dominance of the Ptolemaic system.
He was drawn to ideas of the sun and stars as nobler
bodies than the earth, and of the earth’s daily rotation

and annual revolution. By  May  he wrote a small
tract presenting a theory of celestial motion which
included a central sun and a moving earth. He circulated a draft of this heliocentric theory among trusted
friends, but evidently concluded, upon the publication
of Ptolemy’s complete Almagest in , that a more
extensive mathematical treatment was required to
support his own conclusions.
Leonard Digges, ca. –?
A Prognostication Everlasting of Ryght Good Effecte
The seconde impression augmented by the author
London: Thomas Gemini, 
Collection of Jay M. Pasachoff
His De Revolutionibus Orbium Coelestium (“On
the Revolutions of the Celestial Spheres”) was published at last in . Some  copies were printed;
one was presented to Copernicus on his deathbed.
The work was widely admired as a sophisticated
treatise, even by many readers who rejected a suncentered system out of hand; within a hundred years
its central thesis was generally accepted. Meanwhile,
it led to the more advanced work of Tycho Brahe,
Johannes Kepler, and Galileo Galilei. Its diagram
of a heliocentric system is perhaps the most famous
scientific illustration in history.
Christoph Clavius, –
In Sphaeram Ioannas de Sacro Bosco Commentarius
Venice: Bernard Basam, 
Collection of Jay M. Pasachoff
Digges is concerned here with practical astronomical
and astrological rules connecting the heavens (on
the Ptolemaic model), the weather, the tides, and the
human body. Thus (for example) “the conjunction,
quadrature, or opposition of Iuppiter with the Sunne
[signifies] great and moste vehement wyndes”;
“cometes signifie corruption of the ayre”; and “these
Signes are moste daungerous for bloud letting, the
Moone beyng in them: Taurus, Gemini, Leo, Virgo
and Capricornus, with the last halfe of Libra, and
Scorpius.” Some of his tables, such as that of the
altitude of the sun, are said to have been helpful
to sailors.
In  the author’s son, astronomer Thomas
Digges, published a new edition of the Prognostication
which included a version of the Copernican arrangement of planets, for the first time within a universe
of stars said to be at varying distances rather than
on a fixed concentric sphere.
Clavius entered the Jesuit order in , and for most of
his life was a professor of mathematics at the Collegio
Romano in Rome. His treatise on the Sphaera Mundi
of Joannes de Sacro Bosco (John of Holywood, fl. ),
for centuries the most esteemed text on spherical
astronomy, was originally published in Rome in 
and later often reprinted. For more than forty years it
was used as an introductory textbook in many schools.
Clavius was a strong supporter of the Ptolemaic system
and an opponent of Copernicus, whom he accuses
near the end of this work of a false, indeed an absurd
doctrine.

Tycho Brahe, –
Astronomiae Instauratae Mechanica
Nuremberg: Levinus Hulsius, 
Gift of Alfred C. Chapin, Class of 
Johannes Kepler, –
Prodromus Dissertationum Cosmographicarum,
continens Mysterium Cosmographicum
Tübingen: Georg Gruppenbach, 
Collection of Jay M. Pasachoff
Tycho Brahe, –
Astronomiae Instauratae Progymnasmata
Prague: [Heirs of Tycho Brahe], 
Collection of Jay M. Pasachoff
Johannes Kepler spent much of his life attempting to
discover the true mechanism of the universe and its
driving force. In , concerned to explain the number
of the known planets, their relative positions, and their
motions, he conceived the idea that the orbits of the
six known planets (assumed to be circular paths) were
related in proportion to the five regular geometric
solids. In his first book, briefly called the Mysterium
Cosmographicum (“The Cosmographical Secret”),
he dramatically presented the planetary orbits as
nested spheres, in which were inscribed an octahedron
(eight faces, between the orbits of Mercury and Venus),
an icosahedron (twenty faces, between Venus and
Earth), a dodecahedron (twelve faces, between Earth
and Mars), a tetrahedron (pyramid, between Mars
and Jupiter), and a cube (between Jupiter and Saturn).
That this scheme worked with fair accuracy was
sheer coincidence. Its real importance lies in its
advance of the Copernican system, and by stressing
a central sun as the force by which the planets were
kept in motion.
Astronomiae Instauratae Progymnasmata
Frankfurt: Godfried Tambach, 
Collection of Jay M. Pasachoff
For more than twenty years beginning in , Tycho
Brahe made significant observations of the heavens
from the Danish island of Hven. His observatory,
Uraniborg, was then the finest in Europe. Recognizing
that the improvement (or “reform”) of astronomy
relied on accurate observations, he designed and built
new instruments, and with his assistants plotted the
course of celestial bodies more fully and more precisely
than his predecessors. His instruments and observatory
are displayed for posterity in his Astronomiae Instauratae Mechanica (“Instruments for the Reform of
Astronomy”).
The Astronomiae Instauratae Progymnasmata
(“Exercises in the Reform of Astronomy”), shown
in the first edition of  and a second issue of ,
is Tycho’s principal work. It was published after his
death in Prague, where he had been named imperial
mathematician by Emperor Rudolf II. It contains his
theory of lunar and solar motion, part of his important
catalogue of stars, and a more detailed analysis of the
nova of  in Cassiopeia than he had published in a
small book on the subject in . Shown is a diagram
of his own view of the universe: although he did not
fully accept the Ptolemaic system, Tycho held to his
belief in a stationary earth, in part because of the dictates of Scripture. Therefore in the so-called Tychonic
system the sun revolves around the earth, but the
other planets orbit the sun.

Johannes Kepler, –
Ad Vitellionem Paralipomena, quibus
Astronomiae Pars Optica Traditur
Frankfurt: Claudius Marnius and
the heirs of Jean Aubry, 
Gift of Alfred C. Chapin, Class of 
Johannes Kepler, –
Astronomia Nova seu Physica Coelestis,
Tradita Commentariis de Motibus Stellae Martis,
ex Observationibus G.V. Tychonis Brahe
Prague, 
Collection of Jay M. Pasachoff
On  July  Kepler observed a partial solar
eclipse. After this event he conducted research in
optics, and as in everything else made significant
advances. Although he intended at first to publish
simply an appendix to Witelo, a th-century scholar
who had written about optics, Kepler expanded his
program to include discussion of parallax, refraction,
eclipses, and the solar image.
In the early th century Kepler worked diligently to
find a unified, physically acceptable mathematical
model of planetary motion, in particular as it applied
to the notably eccentric orbit of Mars. At length he
realized that Mars’ orbit could not be circular: only
an ellipse would satisfy Tycho’s data. From this,
extrapolating from Mars to the other planets, he
formulated what came to be called his First Law:
that the planets orbit in ellipses, with the sun at one
focus. He also found that a planet moves in such a
way that a line drawn from it to the sun sweeps out
equal areas of its orbit in equal times – that is, the
closer a planet is to the sun, the faster it moves.
This came to be known as Kepler’s Second Law.
Kepler explained these revolutionary discoveries
in a book he called, with some justification, “The
New Astronomy, or Celestial Physics, Treated by
Means of Commentaries on the Motion of the
Star Mars.”
Johannes Kepler, –
De Stella Nova in Pede Serpentarii, et . . . Trigono Igneo
Pragae: Paulus Sessius [etc.], 
Collection of Jay M. Pasachoff
In  Kepler became an assistant to Tycho Brahe in
Prague, albeit limited by his employer to a study of the
orbit of Mars. On Tycho’s death in  Kepler was
made his successor as imperial mathematician and
was able to use Tycho’s wealth of astronomical data
to advance his own ideas on planetary motion. In 
he published a collection of observations and opinions,
De Stella Nova, the principal concern of which is the
“new star” or nova that appeared at the same time
and in the same vicinity as a series of planetary conjunctions in the three “fiery” signs of the zodiac,
Sagittarius, Leo, and Aries. He relates the nova to
the Star of Bethlehem, which he dates to  ...
An engraved plate illustrates the nova, marked
“N”, in the heel of the serpent-bearer, Ophiuchus,
near a conjunction of Mars, Jupiter, and Saturn.
The figure is evidently based on that in the map of
“Serpentaria” in Bayer’s famed star atlas Uranometria
(, also in this exhibition), but turned to face the
viewer.
Johannes Kepler, –
Harmonices Mundi
Linz: Published by Godfried Tambach,
printed by Johann Planck, 
Collection of Jay M. Pasachoff
Despite the advances he made in his Astronomia
Nova, Kepler was still short of a greater goal, of
making manifest the harmony of the universe as it
pertained to the individual. In the first two parts of
his “Harmony of the World” he examines polygons
and polyhedrons, in search of a geometrical basis for
the archetypal principles of the universe. In the third
part he discusses musical harmony relative to geometrical ratios. In the fourth he expresses his views
on astrology: although Kepler largely dismissed the
practice as foolish, he believed in the harmonic significance of the configuration of the heavens.

Galileo Galilei, –
Sidereus Nuncius
Venice: Apud Thomam Baglionum, 
Collection of Jay M. Pasachoff
Finally in the fifth part of his book, looking back
to his Mysterium Cosmographicum of , Kepler
returned to the idea of the spacing of the planets based
on the regular solids. He now recognized that his earlier
data had been only approximate, and in searching for
a better explanation found a supposed harmonic
relationship, which at length he developed into what
is now called his Third Law: that the squares of the
periods of the planets are to each other as the cubes
of their mean distances from the sun.
In the summer of  the Italian Galileo Galilei
learned of an optical device for making distant objects
seem close, and soon constructed a “perspicillum”
(telescope) of his own. He documented his first observations in the Sidereus Nuncius or “Starry Messenger
[or Message],” one of the most important works in
the history of astronomy. There he discusses the moon
with mountains, seas, and shadows (not, as others had
supposed, as a crystalline sphere); a multitude of stars
not visible with the naked eye; and most importantly,
four satellites of Jupiter, depicted simply with asterisks
for the moons and a large letter O for the planet.
Johannes Kepler, –
Tabulae Rudolphinae
[Ulm]: Johann Saur, 
Collection of Jay M. Pasachoff
Kepler’s “Rudolphine Tables” (named after the late
emperor Rudolf II) set a new standard for precision
in astronomical tables, far in advance of their predecessors. With these one can calculate, if by a complicated process, the position of a planet for any date
or time in the past or future. As their superiority was
proved in use, the tables also demonstrated the truth
of the Copernican system on which they were based.
They remained the standard astronomical tables for
the next hundred years.
The work is preceded by an allegorical frontispiece,
designed by Kepler, sketched by his Tübingen friend
Wilhelm Schickard, and engraved by Georg Celer of
Nuremberg. It depicts the Temple of Urania, muse of
astronomy, modeled after the foyer of Tycho’s observatory on Hven. The columns represent advances in
science, ending with an elegant Corinthian column
associated with Tycho. The Tychonic system is shown
on the ceiling of the temple; below, Tycho points it
out to Copernicus. They are accompanied by the
figures of Hipparchus and Ptolemy. On the temple
dome are six goddesses of science, and hovering above
them is the imperial eagle, dropping largesse for the
support of astronomy. Kepler himself is pictured,
humbly working by candlelight, in one of the bottom
panels, where (pointedly) only a few of the imperial
coins come to rest.
Galileo’s discovery of these four “new planets”
partially justified Copernicanism by demonstrating
that it was not only the earth around which heavenly
bodies revolved.
In the Pasachoff copy, the Sidereus Nuncius is
bound with three other astronomical works: Dianoia
Astronomica, Optica, Physica, qua Syderei Nuncij Rumor
de Quatuor Planetis à Galilaeo Galilaeo by Franciscus
Sitius (Venice, ); De Radiis Visus et Lucis in Vitris
Perspectivis et Iride by Marco Antonio de Dominis
(Venice, ), and Breve Instruttione sopra l’apparenze
et mirabili effetti dello specchio concavo sferico by
Giovanni Antonio Magini (Bologna, ).

Galileo Galilei, –
Istoria e dimostrazioni intorno alle macchie solari e loro
accidenti: comprese in tre lettere scritte all’illustrissimo
Signor Marco Velseri . . .
Rome: Giacomo Mascardi, 
Collection of Jay M. Pasachoff
Although the Dialogo does, indeed, consider both
systems of celestial motion, it was hardly impartial:
naive Simplicio is made to put up ineffectual arguments for Salviati to counter, while Sagredo is generally
persuaded by Salviati. It is a masterly argument, which
served more than any other work to make the Copernican system a commonplace. But it led to Galileo
being condemned by the Inquisition to permanent
house arrest and forced to abjure all that the Dialogo
professed. Copies, however, went into circulation before
the censure.
Preceding the title-page of the first edition is a
famous added engraved title-leaf by Stefano della
Bella, depicting Aristotle, Ptolemy, and Copernicus
in discussion.
In , three years after he built his “perspicillum,”
Galileo observed sunspots by projecting the sun’s image
onto a piece of paper, adjusted so that the
diameter of the sun was equal to that of an inscribed
circle. For each observation he used a fresh sheet of
paper, and within the circle marked the projected
sunspots in ink. Thus he recorded a series of images,
thirty-eight of which were made into etchings and
reproduced in his “History and Demonstrations
Concerning Sunspots and Their Properties.” Major
spots are labeled with letters for easier tracking from
observation to observation. The successive images
clearly show the movement of particular spots across
the sun’s surface, caused by the sun’s rotation on
its axis.
In his text Galileo states for the first time that he
believed his telescopic discoveries to be in harmony
with the “great Copernican system”.
Galileo Galilei, –
Dialogo di Galileo Galilei . . . sopra i due massimi
sistemi del mondo Tolemaico, e Copernicano
Florence: Giovanni Battista Landini, 
Collection of Jay M. Pasachoff
Simon Marius, –
Mundus Iovialis Anno M DC IX Detectus Ope Perspicill
Belgici: Hoc est, Quatuor Jovialium Planetarum, cum
Theoria, tum Tabulae, Propriis Observationibus
Maxime Fundatae
Nuremburg: Johann Laur, 
Collection of Jay M. Pasachoff
The Congregation of the Index having issued in 
a general decree against defending the Copernican
system in print, for a while Galileo avoided the issue.
Then in  he received from the Pope Urban VIII
permission to discuss Copernicanism in a book
provided that the Ptolemaic-Aristotelian view also
received equal and impartial consideration. The
result was Galileo’s “Dialogue on the Two Great
World Systems,” set in the form of an open discussion
between three friends: Simplicio, who takes the orthodox view; Sagredo, an intelligent layman; and Salviati,
who speaks for Galileo.
Like Galileo Galilei, the German mathematician
Simon Marius learned of the telescope, constructed
one, and used it to make astronomical observations.
That he too observed the moons of Jupiter by the end
of December  is without doubt; but in his Mundus
Iovialis, the full title of which translates as “The Jovian
World, Discovered in  by Means of the Dutch
Telescope,” he claimed to have done so even earlier,

in advance of Galileo (as documented in his Sidereus
Nuncius of ). Galileo took offense and issued a
blistering reply, accusing Marius of theft and usurpation.
Regardless of which observer has priority, Marius
was the first to publish tables of the motions of the
Jovian satellites, and – as announced in Mundus Iovialis
– the first as well to observe the Andromeda nebula.
His first important publication was the Selenographia, a book of notable substance and beauty.
After describing the manufacture of lenses and telescopes, Hevelius delineates the markings on the moon
and discusses its libration. Many of the names he gave
to lunar mountains, craters, and other formations
are still used. He provides spectacular lunar maps,
and engravings of the moon throughout its phases.
His detailed observations of the sun, more accurate
than those of his predecessors, and on the moons
of Jupiter, are recounted in an appendix.
Johannes Hevelius, –
Selenographia
Gdansk: Published by the author,
printed by Andreas Hünefeld, 
Collection of Jay M. Pasachoff
Isaac Newton, –
Philosophiae Naturalis Principia Mathematica
London: Joseph Streater, for Sam. Smith, 
Collection of Jay M. Pasachoff
Johannes Hevelius of Gdansk studied law but in
 devoted himself to astronomy. Wealth from his
family’s brewing business, as well as a royal pension,
allowed him to construct a series of private observatories at his home. He also built his own precision
measuring instruments and telescopes, with which
he made numerous observations. In order to publish
his findings he established his own press and became
a skilled engraver.
Although it could be deduced from Kepler that the
force attracting a planet to the sun is inversely proportional to the square of the distance between the
two bodies, mathematical proof of this was elusive.
Encouraged by his friend Edmond Halley, the brilliant
mathematician Isaac Newton addressed the problem
and produced the first successful scientific model of
the mechanisms of the universe.
In his “Mathematical Principles of Natural Philosophy” (i.e., Physics) Newton modifies and expands
not only Kepler’s laws, but findings by Galileo on the
nature of falling bodies and the motion of projectiles.
The result is a “divine treatise” (in Halley’s words)
in which Newton puts forth his own three laws of
motion, as well as a law of universal gravitation
which showed that all bodies exert a force of mutual
attraction, greater or lesser according to their mass
and the distance between them.
The Principia Mathematica powerfully explained
all of the motions of the heavenly bodies as they were
then known. It was the culmination of the scientific
revolution that began with Copernicus, and ushered
in the Age of Reason.

Isaac Newton, –
A Treatise of the System of the World
London: Printed for F. Fayram, 
Collection of Jay M. Pasachoff
Joseph von Fraunhofer, –
Bestimmung des Brechungs- und FarbenzerstreuungsVermögens verschiedener Glasarten
Munich: Gedruckt mit Lentner’schen Schriften, []
Collection of Jay M. Pasachoff
Newton’s Principia Mathematica was preceded in its
development by a shorter work in two parts, De Motu
Corporum (). The second of these, written in a
more “popular” style than the Principia, was later published in Latin as De Mundi Systemate, and in English
(translated probably by Andrew Motte) as The System
of the World. Here, with greater exposition and less
mathematics, Newton writes of fluid space through
which planets and comets are propelled and the
forces that govern their motion.
In the course of determining the optical constants of
glass, Fraunhofer compared the effect on the refracting
medium of light from flames and light from the sun,
and found the solar spectrum crossed with hundreds
of fine dark lines. Moreover, he noted that while the
spectra observed for the sun and planets were identical,
those for other bright stars were different, and differed
from one another. Later the dark “Fraunhofer lines,”
which mark the presence of different elements in the
source, provided a means of demonstrating that stars
are made of matter like terrestrial substances, rather
than some exotic material. In  Sir William Huggins
determined that older stars have more complex spectra,
i.e., a greater number of Fraunhofer lines.
Fraunhofer’s “Definition of the Capacity of Refraction and Colour-diffusion of Various Kinds of Glass”
is considered one of the fundamental papers of
astrophysics.
Edmond Halley, ?–
Tabulae Astronomicae: Accedunt de
Usu Tabularum Praecepta
London: William Innys, 
Collection of Jay M. Pasachoff
The most famous achievement of the English polymath Edmond Halley was his scheme for computing
the position of comets and establishing their periodicity. When the comet of  reappeared as Halley
predicted in , fifteen years after his death, it was
given his name. He also made notable advances in
determining the distance of the sun from the earth,
in positional and navigational astronomy, and in
planetary and stellar observations. As an established
figure of some means he lent support to others, such
as Isaac Newton.
Part of his Tabulae Astronomicae, published
posthumously, concerns the “long inequality” of
the orbits of Jupiter and Saturn, which had made
previous planetary tables inaccurate. Halley suggests
that the phenomenon might be due to a gravitational
attraction between the two planets.
Albert Einstein, – et al.
Annalen der Physik
th series, Band 
Leipzig: Verlag von Johann Ambrosius Barth, 
Collection of Jay M. Pasachoff
This volume includes three of five papers published
by Einstein in the year that has been called his annus
mirabilis: “Über einen die Erzeugung und Verwandlung des Lichtes betreffenden heuristischen Gesichtspunkt” (“On a Heuristic View Concerning the Production and Transformation of Light”); “Über die von der
molekularkinetischen Theorie der Wärme geforderte
Bewegung von in ruhenden Flüssigkeiten suspendierten Teilchen” (“On the Motion of Small Particles
Suspended in a Stationary Liquid According to the
Molecular Kinetic Theory of Heat”); and “Zur Elektrodynamik bewegter Körper” (“On the Electrodynamics
of Moving Bodies”).

Richard P. Feynman
QED: The Strange Theory of Light and Matter
Princeton, N.J.: Princeton University Press, 
Collection of Jay M. Pasachoff
Of these the most significant is the last, which
outlines the Special Theory of Relativity – “special”
because it applies only to bodies moving in the absence
of a gravitational field, “relativity” because it held that
all motion is relative. Einstein postulated that if the
speed of light were the same for all observers, and that
all observers moving at constant speed observed the
same physical laws, then time intervals change according to the speed of the system relative to the observer’s
frame of reference. The effect becomes noticeable,
however, only at very high velocities, approaching
light speed.
In this book California Institute of Technology
professor Richard P. Feynman explains the theory
of quantum electrodynamics – the interaction of light
and electrons – for a general if well-educated audience.
The Pasachoff copy contains the author’s signature and
an original “Feynman diagram” – a graphic method of
representing the interactions of elementary particles.
Albert Einstein, –
Die Grundlage der allgemeinen Relativitätstheorie
Leipzig: Verlag von Johann Ambrosius Barth, 
Collection of Jay M. Pasachoff
In his theory of Special Relativity () Einstein was
concerned with bodies in uniform motion and in the
absence of gravity. Later he extended this to apply
more generally, hence the theory of General Relativity.
In Newtonian physics, the space in which physical
phenomena occur is a three-dimensional continuum;
but under General Relativity, space and time are considered as a single entity, space-time, within which
any mass exerts a gravitational field which warps
space-time around it and affects even electromagnetic
radiation passing through the field. The sun’s gravity,
for instance, attracts, bending slightly, a ray of light
from a distant star; and light radiated from the sun
interacts with the sun’s mass, resulting in a shift in
the spectrum of the light toward the infrared.
The consequences of this theory have been
enormous, not least in its revision of the concept
of gravity that had long been held since Newton
wrote his Principia Mathematica ().
STAR ATLASES
The Pasachoff collection of rare astronomy books
includes most of the great and important star atlases.
These are among the most beautiful scientific books
ever published – art in the service of science, but works
of science first. De le stelle fisse by Piccolomini ()
could be called the first star atlas, while Bayer’s Uranometria () set the standard of comparison for all
that came later. The period of the great star atlases
culminated with that of Bode in , the most monumental of all in size and number of stars. After Bode
it was no longer feasible to depict all of the known
heavens, overlaid with the figures of constellations.

Alessandro Piccolomini, –
De le sfera del mondo . . . [with] De le stelle fisse
Venice: Al Segno del Pozzo, 
Collection of Jay M. Pasachoff
Piccolomini, Archbishop of Patrasso and from
 assistant to the Archbishop of Siena, translated
Classical authors and himself wrote poetry and plays.
His most popular work, however, was De la sfera del
mondo (“On the Globe of the World”). This begins
with a discussion of cosmography as it was known at
the time, then in De le stelle fisse (“On the Fixed Stars”)
Piccolomini documents with tables and charts all but
one of the constellations known to Ptolemy, as well as
that of the Southern Cross. In his charts the stars are
placed with care, without overlaid pictorial figures.
Four levels of magnitude are represented, and a
system of letters (later modified by Bayer) is used
to mark the most notable stars in each constellation.
Johannes Bayer, –
Uranometria
Augsburg: Christophorus Mangus, 
Collection of Jay M. Pasachoff
Johannes Hevelius, –
Firmamentum Sobiescianum sive
Uranographia Joh. Hevelii
Gdansk: Johann Zacharias Stolle,  [i.e., ]
Collection of Jay M. Pasachoff
Detail illustrated above
Bayer’s Uranometria is the most illustrious and
historically important of all star atlases. It includes
fifty-one bifolium charts, engraved by Alexander Mair
(ca. –), each with perimeter grids so that star
positions can be read to fractions of a degree. In the
first edition only, as here, text is printed on the backs
of the plates.
Bayer, a lawyer who was also an amateur astronomer, addressed the problem of a standard nomenclature in referring to individual stars, modifying the
system of notation employed by Piccolomini in .
Bayer assigns to each star (visible to the naked eye)
in a given constellation a Greek letter, or for those
constellations with more than twenty-four stars, a
roman letter, generally in order of magnitude. The
main authorities for the positions of the stars shown
in Bayer’s plates were the then-recent northern
observations of Tycho Brahe and the southern observations of the Dutch navigator Pieter Dirckszoon
Keyzer.
Hevelius also compiled a new star catalogue from
his own observations. From this, together with
Edmond Halley’s  catalogue of the southern
stars, he produced an atlas to rival Bayer’s in accuracy
and innovation. Each chart is presented unusually as
it would be on a globe, from a point of view outside
of the constellations rather than as seen from the
earth; thus the direction of the constellations is
reversed from more familiar pictures.
Of eleven new constellations introduced in the
Uranographia, four were subsumed into other
figures, but seven are still recognized today.

Johann Gabriel Doppelmayr, –
Atlas Coelestis
Nuremberg: Heirs of Johann Homann, 
Collection of Jay M. Pasachoff
conical projection in which all parallels of declination
are equidistant straight lines.
In  the French globe maker Fortin produced
the first revision of Flamsteed’s atlas, increasing the
original twenty-six plates to twenty-seven by dividing
that for Hydra in two. The aesthetic appeal of Flamsteed’s original figures was also much improved in
the process. Further additions and alterations to
Flamsteed’s atlas led ultimately to Bode’s Uranographia of .
Doppelmayr was a scholar of high repute, professor
of mathematics at Nuremberg for nearly fifty years.
He wrote widely on astronomy, geography, and
allied subjects, and often worked with the influential
cartographic publisher Johann Baptista Homann or
his heirs. The “Celestial Atlas” is his major work,
intended as an introduction to the fundamentals of
astronomy. It contains a wealth of star maps, charts,
and other guides to the heavens and their study,
presented with style and packed with detail. Most
of its plates had appeared in atlases published by
Homann as early ; the plate shown, concerned
with eclipses and transits of the sun, dates between
 and . The central picture shows the path
of the solar eclipse of  May  across Europe
and northern Asia.
Although the present copy is lacking its added
engraved title-leaf, Professor Pasachoff was able to
purchase a separate example on larger paper. Drawn
by Johann Justin Preisler and engraved by Johann
Christoph von Reinsperger, it depicts four of Doppelmayr’s illustrious predecessors – Ptolemy, Copernicus,
Kepler, and Brahe – beneath a diagram of the solar
system and the outer heavens. A comet is seen to
describe a parabolic path around the sun.
John Bevis, –
Uranographia Britannica (or Atlas Celeste)
[London]: Printed –, published 
Collection of Jay M. Pasachoff
John Bevis was a physician and amateur astronomer,
the original discoverer of the Crab Nebula (M) in
 and one of only two persons in Britain known
to have observed Halley’s comet on its first predicted
return in . Around  Bevis entered into an
undertaking with a London instrument maker, John
Neale, to prepare a new star atlas which in accuracy
and beauty would surpass those of Bayer and Flamsteed, on which it would be based along with the star
catalogues of Halley and Hevelius. Plates were made
stylistically following Bayer, but showing peripheral
as well as primary constellations. These depict six
hundred more stars than Flamsteed’s atlas of ,
altogether more than ,, according to their
zodiacal positions.
John Flamsteed, –
Atlas céleste
Seconde édition, par M.J. Fortin
Paris: Chez F.G. Deschamps; chez l’Auteur, 
Collection of Jay M. Pasachoff
As Astronomer Royal at Greenwich, Flamsteed
compiled the first telescopic catalogue of the positions
and magnitudes of the northern stars, and prepared
an accompanying set of maps. These were first published in  by Flamsteed’s friends after his death.
They are drawn on what has come to be known as the
Sanson-Flamsteed sinusoidal projection, a modified

The image shown in the exhibition, featuring the
constellation Taurus (see detail on p. ), also shows
not only the Crab Nebula but also the planet Uranus,
observed as a “star” by Flamsteed in . Each plate
includes the name of one of the book’s proposed
sponsors.
At least a few impressions were made of the charts
by autumn ; but then Neale went bankrupt, and
the copperplates were seized by the court. In ,
however, bound sets of Bevis’s star charts were offered
for sale under the title Atlas Celeste. Twenty-three
copies are known to survive, in varying degrees of
completeness. The Pasachoff copy contains the rare
index of plates, but not the broadsheet title-leaf.
Joannis Elerti Bode, –
Uranographia
Berlin: Apud Autorem, 
Collection of Jay M. Pasachoff
Bode was the director of the observatory of the Berlin
Academy of Science for forty years. This, his final
celestial atlas and the largest ever published, includes
two hemisphere maps and eighteen maps of ninetynine constellations, centered on the vernal and autumnal equinoxes. It surpassed all of its predecessors by
recording , stars (compared with , in Bayer
some two hundred years earlier), and by containing
for the first time the nebulae, star clusters, and double
stars catalogued by William Herschel. Nearly every
constellation ever invented is present, as well as five
new ones, some fancifully depicted but now lost to
history.
Bode’s Uranographia was also the last great star
atlas, after which it was not feasible to include in a
single large work all of the features known to be in
the heavens. Popular charts concentrated only on
stars visible to the naked eye, while those prepared
for astronomers reduced or eliminated the traditional
constellation figures.
Thomas Jefferys, d. 
The Geography of the Great Solar Eclipse of July 
MDCCXLVIII []: Exhibiting an Accurate Map
of All Parts of the Earth in Which It Will Be Visible,
with the North Pole, According to the Latest
Discoveries by G. Smith Esqr.
London: E. Cave, 
Collection of Jay M. Pasachoff
This plate, engraved by Thomas Jefferys, was issued
originally in A Dissertation on the General Properties
of Eclipses by George Smith (London, ).
*
Handlist text and design by Wayne G. Hammond,
Assistant Librarian, Chapin Library. The cover art is
taken from one of twenty-five late th- to early thcentury astronomical plates, partly from an unknown
edition of James Ferguson’s Astronomy Explained
upon Sir Isaac Newton’s Principles, first published
in  (Collection of Jay M. Pasachoff ).
Detail from portrait in Simon Marius, Mundus Iovialis, 1614, the first
illustration of a telescope or perspicillum (Collection of Jay M. Pasachoff)