MODERN ASTRONOMY.
Still, however, the world was not convinced of the truth of the
Copernican system. One man here or there saw and acknowledged its
reality. The mass of mankind continued firmly to believe that they
dwelt at the universe center, and utterly to scout the idea of a moving
earth. Indeed, it may be very much doubted whether, not merely the
mass of mankind, but even the most civilized and cultivated portion of
that mass, had as yet, to any wide extent, heard a whisper of the new
theories. Knowledge, in those days, traveled from place to place with
exceeding deliberation.
Another great man arose, contemporary with Kepler--a man whose story
seizes more strongly upon our imagination than that of the severe and
successful studies of Kepler. From an ordinary worldly point of view,
Kepler would hardly be looked upon as altogether a successful man. He
was poor, and in sickly health. His chief book was promptly prohibited
by Rome--then a power in the whole reading world of Europe to an extent
which can hardly be realized in these days of freedom. Kepler’s book
was placed in the forbidden category, side by side with the dying
publication of Copernicus. This checked all hope of literary gains, and
life with Kepler was one long struggle. But if he could have looked
ahead two or three hundred years; if he could have foreseen the time
when not a few wise men of science alone, but all the civilized world,
including the very Church which condemned him, should meekly have
accepted and indorsed his discoveries,--then he would have been able to
gauge the measure of his own real success.
Moreover, with all his troubles, Kepler was so happy as to escape
absolute persecution. He lived in a country which knew something of
liberty as an ideal; he was left to write and work freely; and, at
least, no public recantation of what he held to be truth was forced
from him.
Galileo’s was a sadder tale. A Florentine of noble birth, he turned his
attention early to science as the needle turns to the north, and before
the age of twenty-seven he already occupied a foremost position as
mathematical lecturer at Pisa. There it was that he direfully offended
the philosophers of the day by proving Aristotle to be in the wrong.
For Aristotle was the great master of the schoolmen. His philosophy
and theories were accepted as final, and whatsoever could not be
proved in accordance with them was regarded as untrue. Aristotle had
declared that if two weights--the one being ten times as heavy as the
other--were dropped together from a height, the heavier weight would
reach the ground ten times as quickly as the lighter.
Everybody believed this, and nobody had ever thought of putting it to
the test of actual trial. Aristotle had said so, and Aristotle was
indorsed as a whole by all the schools of Europe; and what more could
possibly be wanted by any reasonable human being? But Galileo was not
so easily satisfied. He looked into the matter independently, bent upon
finding out, not what Aristotle had thought or what the Church might
support, but simply what actually _was_.
[Illustration: PROMINENT ASTRONOMERS OF THE NINETEENTH CENTURY.]
Then, in view of many observers, called together for the occasion, he
dropped, at the same instant, from the top of the leaning tower of
Pisa, a shot weighing one pound and another shot weighing a hundred
pounds. And, behold! both reached the ground simultaneously. There was
not a fraction of difference between the two. To prove Aristotle wrong
was to prove everybody wrong, the authorities of the Church included.
Men calmly declined to believe their own eyes, and Galileo was in very
evil odor.
From falling bodies he went on to subjects of yet wider interest to
people in general. He read about and eagerly embraced the Copernican
system. Not only did he accept it himself, but he vigorously set
to work to teach and convince others also. This, as might only be
expected, aroused vehement opposition. But Galileo was still in the
heyday of his powers, and he was not to be easily silenced. In those
days he could afford to press onward in the teeth of resistance, and to
laugh at men who would not listen.
When at Venice, a report reached him of a certain optician in Holland
who had happened to hit upon a curious “combination of lenses,” through
which objects afar off could be actually seen as if they were near.
Galileo promptly seized upon the notion, and within twenty-four hours
he had rigged up a small, rough telescope out of an old organ-pipe and
two spectacle-glasses.
Thus the first telescope was made--a very elementary affair, formed of
two lenses, convex and concave, and capable of magnifying some three
times--a mere child’s toy compared with telescopes of the present day,
but of exceeding value and interest, because it was the very first;
because in all the history of the world no telescope had ever been
manufactured before.
This earliest effort was speedily improved upon. The next trial
produced a tube which could magnify seven or eight times; and in a
little while, Galileo had a telescope magnifying as much as thirty-two
times. Even thirty-two times does not sound very startling to us; but
in those days the revelations of such an instrument came upon men like
a thunderclap.
Through it could be seen clearly the broken nature of the moon’s
surface--the craters, the shadows, the mountains. Through it could be
seen the phases of Venus, which no man had ever yet detected, but which
Copernicus had declared must certainly exist, if indeed his system
were a reality. Through it could be seen four of the moons of Jupiter,
and their ceaseless journeyings. Through it could be seen spots upon
the face of the sun, the movements of which showed the rotation of the
sun upon his axis. Through it could be seen the very curious shape of
Saturn, caused by his rings, though a much stronger power was needed to
separate the rings from the body of the planet.
Of all these discoveries, and many others also made by Galileo, none
seemed worse to the bigoted schoolmen of his day than the preposterous
notion of black spots upon the sun’s face.
Rather curiously, no human being seems ever before then to have noticed
such spots, though often they are quite large enough to be detected by
the naked eye. A general belief had been held that the sun was and must
be perfect--an absolutely spotless and unblemished being, the purest
symbol of celestial incorruptibility--and the said discovery went right
in the teeth of deductions drawn from, and lessons founded upon, this
belief. Therefore the schoolmen held out and determinedly resisted, and
would have nought to do with Galileo or his telescopes, shutting their
eyes to marvels newly revealed.
But Kepler was a true scientist, a man who earnestly pursued truth,
and sought to discover it at any hazard. He and Galileo were
contemporaries, and they held communication on these subjects. Some
of Galileo’s discoveries went quite as much in the teeth of some of
Kepler’s most dearly-loved theories as they did in the teeth of the
schoolmen’s most dearly-loved doctrines. Yet, none the less, Kepler
welcomed them with great delight and eagerness, showing thereby his
true greatness of character.
Till after the age of fifty, Galileo was allowed to go on undisturbed,
or at least not materially disturbed, by opposition in his career of
success--observing, learning, theorizing, calculating, explaining,
teaching--a prominent figure indeed. Not only did he take a large share
in establishing firmly the Copernican system of astronomy, but some of
the principal laws of motion were discovered by him. He first found
the uses of a pendulum, and there is strong reason for believing that
the first microscope, as well as the first telescope, was from his
hands.
But after the age of fifty, reverses came, and one blow succeeded
another. Rome had been gradually waking up to the true sense of all
that was implied by his discoveries and his teaching, and at length she
let loose her thunders--impotent thunders enough, so far as regarded
any permanent checking of the progress of truth, but by no means
impotent to crush one defenseless victim, the champion of scientific
truth in that country and age.
Years of greater or less opposition, amounting often to persecution,
were followed by an imperious order commanding him to Rome. There he
was examined and severely “questioned,” and recantation was forced from
him, worth as much as such forced recantations commonly are worth.
Even then he did not cease from the work that he loved; even in prison
he carried it on; even when he might not write, nothing could stop him
from thinking. But his health was broken; his liberty was taken away;
illness followed illness; his favorite daughter died; his eyesight
gradually failed; the last book that he wrote might not for a long
while be printed; and at last he passed away, mercifully set free from
those who, in an essentially bigoted and intolerant age, were incapable
of appreciating his greatness.
They would fain _then_ have denied him even a respectable grave. Now,
all the civilized world unites to honor the name of Galileo.
CHAPTER XXXIII.
ISAAC NEWTON.
Even the great fame of Galileo must be relegated to a second place in
comparison with that of the philosopher who first saw the light in a
Lincolnshire farmhouse on the 25th of December, 1642, the very same
year of Galileo’s death. His father, Isaac Newton, had died before his
birth. The little Isaac was at first so frail and weakly that his life
was despaired of. The watchful mother, however, tended her delicate
child with such success that he ultimately acquired a frame strong
enough to outlast the ordinary span of human life.
In due time the boy was sent to the public school at Grantham. That
he might be near his work, he was boarded at the house of Mr. Clark,
an apothecary. He had at first a very low place in the class. His
first incentive to diligent study seems to have been derived from the
circumstance that he was severely kicked by one of the boys above
him in the class. This indignity had the effect of stimulating young
Newton’s activity to such an extent that he not only attained the
desired object of passing over the head of the boy who had maltreated
him, but continued to rise until he became the head of the school.
The play-hours of the great philosopher were devoted to pursuits very
different from those of most schoolboys. His chief amusement was
found in making mechanical toys, and various ingenious contrivances.
He watched, day by day, with great interest, the workmen engaged in
constructing a windmill in the neighborhood of the school, the result,
of which was that the boy made a working model of the windmill and of
its machinery, which seems to have been much admired as indicating his
aptitude for mechanics. We are told that he also indulged in somewhat
higher flights of mechanical enterprise. The first philosophical
instrument he made was a clock, which was actuated by water. He also
devoted much attention to the construction of paper kites, and his
skill in this respect was highly appreciated by his schoolfellows. Like
a true philosopher, even at this stage, he experimented on the best
methods of attaching the string, and on the proportions which the tail
ought to have.
When the schoolboy at Grantham was fourteen years of age, it was
thought necessary to recall him from the school. His recently-born
industry had been such that he had already made good progress in his
studies, and his mother hoped that he would now lay aside his books,
and those silent meditations to which, even at this early age, he had
become addicted. It was hoped that instead of such pursuits, which were
deemed quite useless, the boy would enter busily into the duties of
the farm and the details of a country life. But before long it became
manifest that the study of nature and the pursuit of knowledge had such
a fascination for the youth that he could give little attention to
aught else. It was plain that he would make but an indifferent farmer.
He greatly preferred experimenting on water-wheels, and working at
mathematics in the shadow of a hedge.
Fortunately for humanity, his mother, like a wise woman, determined
to let her boy’s genius have the scope which it required. He was
accordingly sent back to Grantham school, with the object of being
trained in the knowledge which would fit him for entering the
University of Cambridge.
It was the 5th of June, 1660, when Isaac Newton, a youth of eighteen,
was enrolled as an undergraduate of Trinity College, Cambridge. Little
did those who sent him there dream that this boy was destined to be the
most illustrious student who ever entered the portals of that great
seat of learning. Little could the youth himself have foreseen that the
rooms near the gateway which he occupied would acquire a celebrity from
the fact that he dwelt in them, or that the antechapel of his college
was in good time to be adorned by that noble statue of himself which
is regarded as the chief art treasure of Cambridge University, both
on account of its intrinsic beauty and the fact that it commemorates
the fame of her most distinguished alumnus, Isaac Newton, the immortal
astronomer. His advent at the university seemed to have been by
no means auspicious or brilliant. His birth was, as we have seen,
comparatively obscure, and though he had already given indication of
his capacity for reflecting on philosophical matters, yet he seems to
have been but ill-equipped with the routine knowledge which youths are
generally expected to take with them to the universities.
From the outset of his college career, Newton’s attention seems to have
been mainly directed to mathematics. Here he began to give evidence of
that marvelous insight into the deep secrets of nature which, more than
a century later, led so dispassionate a judge as Laplace to pronounce
Newton’s immortal work as pre-eminent above all the productions of
the human intellect. But though Newton was one of the very greatest
mathematicians that ever lived, he was never a mathematician for the
mere sake of mathematics. He employed his mathematics as an instrument
for discovering the laws of nature.
His industry and genius soon brought him under the notice of the
university authorities. It is stated in the university records that
he obtained a scholarship in 1664. Two years later we find that
Newton, as well as many residents in the university, had to leave
Cambridge temporarily on account of the breaking out of the plague. The
philosopher retired for a season to his old home at Woolsthorpe, and
there he remained until he was appointed a Fellow of Trinity College,
Cambridge, in 1667. From this time onwards, Newton’s reputation as a
mathematician and as a natural philosopher steadily advanced, so that
in 1669, while still but twenty-seven years of age, he was appointed to
the distinguished position of professor of Mathematics at Cambridge.
Here he found the opportunity to continue and develop that marvelous
career of discovery which formed his life’s work.
The earliest of Newton’s great achievements in natural philosophy was
his detection of the composite character of light. That a beam of
ordinary sunlight is, in fact, a mixture of a very great number of
different colored lights, is a doctrine now familiar to every one who
has the slightest education in physical science. We must, however,
remember that this discovery was really a tremendous advance in
knowledge at the time when Newton announced it.
[Illustration: SIR ISAAC NEWTON.]
A certain story is often told about Newton. It is said that as he
sat in a garden an apple fell from a tree, and that its fall set him
thinking, and that, in consequence of this train of thought, he found
out all about the law of attraction or gravitation.
But the fall of an apple could not possibly have set Newton thinking,
because he had already been thinking long and hard upon these
difficult questions. Indeed, it was _because_ he had been so thinking,
_because_ his mind was in a watchful and receptive condition, that so
slight a matter as a falling apple should, perhaps, have suggested to
him a useful train of ideas.
Newton was a man who really did think, and who really did think
intensely. He was not, like the ordinary run of people, one who merely
had a good many notions walking loosely through his brain. He would
bend his mind to a subject and be absolutely absorbed in it; later in
life so absorbed that he would forget to finish his dressing, and would
be unable to say whether or no he had dined. This sort of forgetfulness
does sometimes spring from vacancy of mind; but with Newton it arose
from fullness of thought.
An apple falls, of course, as a stone or any other body falls, because
the earth attracts it. Otherwise, it might as easily rise and float
away into the sky. But this was known perfectly well long before
Newton’s days. It was clearly understood that the earth had a curious
power of drawing all things towards herself. People could not explain
why or how it was so; neither can we explain now; but they were fully
aware of the fact.
So men knew something of the force called gravity; but they knew it
mainly, almost exclusively, as having to do with our earth, and with
the things upon our earth. They had not begun definitely to think of
gravity as having to do with bodies in the heavens; as being a chief
controlling force in the whole Solar System; much less as reigning
throughout the vast universe of stars. It had not come into their
minds with any distinctness that, just as the earth pulls towards her
own center a mountain, a horse, a man, so the sun pulls toward his
center the earth, the moon, and all the planets.
Certain glimmerings of the notion had, indeed, begun to dawn on the
horizon of learning. Horrocks, Borelli, Robert Hook, Wren, Halley, and
others had _glimpses_ of universal gravitation; but only glimpses. A
gifted English philosopher, late in the sixteenth century, Gilbert
by name, went so far as to speak of earth and moon acting one upon
the other “like two magnets.” He also saw the effect of the moon’s
attraction in bringing about ocean tides, though he oddly explained
that the said attraction was not so much exerted upon ocean waters as
upon “subterranean spirits and humors”--whatever he may have meant by
such an expression.
Kepler, not long after Gilbert, made further advance. He gained some
definite notions as to the nature of gravity; and he saw distinctly
that the moon’s attraction was the main cause of the tides. The
following remarkable statement is found in his writings: “If the earth
ceased to attract its waters, the whole sea would mount up and unite
itself with the moon. The sphere of the attracting force of the moon
extends even to the earth, and draws the waters towards the torrid
zone, so that they rise to the point which has the moon in the zenith.”
Here is a distinct enough grasp of the fact that gravity can and does
act through distance, between worlds separated by thousands of miles.
Yet, though both Gilbert and Kepler saw so much, they failed to go
farther. Neither of the two had any clear knowledge of the modes in
which gravitation acts, or of the laws which govern its working.
Gilbert and Kepler alike, while dimly recognizing, not only the moon’s
attraction for earth’s oceans, but the mutual attraction of earth and
moon each for the other, were utterly perplexed as to what force could
possibly hold the two bodies asunder. Gilbert could seriously talk of
“subterranean spirits and humors.” Kepler could soberly write of an
“animal force” or some tantamount power in the moon, which prevented
her nearer approach to earth.
Galileo was equally vague on the subject. With all his brilliant gifts,
and while acknowledging the earth’s attractive power over the moon, he
would not even admit the existence of _mutual_ attraction, and talked
of the moon as being compelled to “follow the earth.” Unquestionably
there are times when the moon does follow the earth, and that is when
the earth happens to go before. But quite as often it happens that the
moon goes before, and the earth follows after.
All these great men were groping near the truth, yet none managed to
find the clue that was wanted. They left the unfinished process of
thought to be carried on by the master-mind of Newton. And Newton set
himself to think the question out. He used Kepler’s observations.
He sought to penetrate the secrets of a Solar System in mysterious
and inviolable order. Some reason or cause for that order he knew
must exist--if only it might be grasped! He pondered deeply; lost in
profound cogitation, through stormy days of civil strife, of plague and
loss and suffering. The object of his life was to discover, if so he
might, what power or what forces retained the different worlds in their
respective pathways; in short, what manner of celestial guidance was
vouchsafed to the planets.
For although men had now learned the shape of the planet-orbits, and
even knew certain laws which helped to govern the planet-motions, they
had not discovered one supreme controlling law. They did not dream of
gravity in the heavens as a prevailing force. There was absolutely no
reason, with which men were acquainted, why each planet should preserve
its own particular distance from the sun; why Mars should not wander
as far away as Jupiter; why Mercury should not flee to the position of
Saturn; why our own earth should be always about as near as she always
is.
The resources of Newton’s genius seemed equal to almost any demand
that could be made upon it. He saw that each planet must disturb the
other, and in that way he was able to render a satisfactory account of
certain phenomena which had perplexed all preceding investigators. That
mysterious movement by which the pole of the earth sways about among
the stars, had been long an unsolved enigma; but Newton showed that the
moon grasped with its attraction the protuberant mass at the equatorial
regions of the earth, and thus tilted the earth’s axis in a way that
accounted for the phenomenon which had been known, but had never been
explained, for two thousand years. All these discoveries were brought
together in that immortal work, Newton’s “Principia,” the greatest work
on science that the world had yet seen.
It may well be that, as Newton pondered this perplexing question
while seated in the garden, an apple dropping to the ground might
have sufficed to turn his wide-awake and ready mind in the direction
of that familiar force, gravity, which draws all loose bodies towards
earth’s surface. The apple fell because of gravity. Quite naturally the
question might have arisen in Newton’s mind--“Why not this same gravity
in the heavens also? If the earth draws an apple towards herself, why
should not the earth draw the moon? Why should not the sun draw the
earth? Nay, more, why should not the sun draw all the planets?” Newton
set himself to work out this problem, allowing for the distance of the
moon from earth, and for the bulk and weight of both earth and moon.
And because the answer was _not_ precisely what he had looked for,
he put the calculation aside, and waited for years. It seems that he
mentioned his conjecture to no living person. After many years he took
it up again, and worked it out afresh. By this time new measurements of
earth’s surface, and new calculations of earth’s size had been made,
and Newton had fresh figures to go upon. This time the answer came
just as he had originally hoped, and the truth of his surmise was thus
proved.
Gravity held the moon near the earth, preventing her from wandering
off into unknown distances. Gravity held earth and moon, Mars, Venus,
Jupiter, each planet, in its own pathway, within a certain distance of
the sun. Gravity held many of the comets as permanent members of the
Solar System. So strong, indeed, was the drawing of gravity found to
be, that only the resisting force of each bright world’s rapid rush
round the sun could keep the sun and his planets apart.
Newton had discovered the long-sought secret. He had found that “every
particle of matter in the universe attracts every other particle?”
He had found also the main laws which govern the working of that
attraction--that it depends, first, upon the mass or amount of “matter”
in each body; that it depends, secondly, upon the distance of one body
from another. He found, too, how far attraction increases with greater
nearness, and decreases with greater distance. All these and countless
other questions he worked out in the course of years. But first he had
grasped the great leading principle, after which men had until then
groped in vain, that by the force of gravity the sun and his worlds
and their moons are all bound together into one large united family or
system.
Though Newton lived long enough to receive the honor that his
astonishing discoveries so justly merited, and though for many years
of his life his renown was much greater than that of any of his
contemporaries, yet it is not too much to say that, in the years which
have since elapsed, Newton’s fame has been ever steadily advancing.
We hardly know whether to admire more the sublime discoveries at
which he arrived, or the extraordinary character of the intellectual
processes by which those discoveries were reached. He died on Monday,
March 20, 1727, in the eighty-fifth year of his age.
CHAPTER XXXV.
LATER ASTRONOMY.
Sir William Herschel was born in the city of Hanover, November 15,
1738. He was the second son of Isaac Herschel, a musician, who brought
him up, with his four other sons, to his own profession.
A faithful chronicler has given us an interesting account of the way in
which Isaac Herschel educated his boys; the narrative is taken from the
recollections of one who, at the time, was a little girl of five or six
years old. She writes:
“My brothers were often introduced as solo performers and assistants
in the orchestra at the court, and I remember that I was frequently
prevented from going to sleep by the lively criticisms on music
on coming from a concert. Often I would keep myself awake that I
might listen to their animated remarks, for it made me happy to see
them so happy. But generally their conversation would branch out on
philosophical subjects, when my brother William and my father often
argued with such warmth that my mother’s interference became necessary
when the names Euler, Leibnitz, and Newton sounded rather too loud for
the repose of her little ones, who had to be at school by seven in the
morning.”
The child, whose reminiscences are here given, became afterwards
the famous Caroline Herschel. The narrative of her life is a most
interesting book, not only for the account it contains of the
remarkable woman herself, but also because it presents the best picture
we have of the great astronomer, to whom Caroline devoted her life.
This modest family circle was, in a measure, dispersed at the outbreak
of the Seven Years’ War in 1756. The French proceeded to invade
Hanover, which, it will be remembered, belonged at this time to
the British dominions. Young William Herschel had already obtained
the position of a regular performer in the regimental band of the
Hanoverian Guards, and it was his fortune to obtain some experience
of actual warfare in the disastrous battle of Hastenbeck. He was not
wounded, but he had to spend the night after the battle in a ditch, and
his meditations on the occasion convinced him that soldiering was not
the profession exactly suited to his tastes. He left his regiment by
the very simple, but somewhat risky, process of desertion. He had, it
would seem, to adopt disguises in order to effect his escape. By some
means he succeeded in eluding detection, and reached England in safety.
The young musician must have had some difficulty in providing for his
maintenance during the first few years of his abode in England.
It was not until he had reached the age of twenty-two that he succeeded
in obtaining any regular appointment. He was then made instructor of
music to the Durham Militia. Shortly afterwards, his talents being more
widely recognized, he was appointed as organist of the parish Church at
Halifax.
In 1766 we find that Herschel had received the further promotion of
organist in the Octagon Chapel, at Bath. Bath was then, as now, a
highly fashionable resort, and many notable personages patronized the
rising musician. Herschel had other points in his favor besides his
professional skill; his appearance was striking, his address superb,
and his conversation animated, interesting, and instructive; and
even his nationality was a distinct advantage, inasmuch as he was a
Hanoverian in the reign of King George the Third. From his earliest
youth, Herschel had been endowed with that invaluable characteristic,
an intense desire for knowledge. He naturally wished to perfect himself
in the theory of music, and thus he was led to study mathematics. When
he had once tasted the charms of mathematics, he saw vast regions of
knowledge unfolded before him, and in this way he was induced to direct
his attention to astronomy. More and more this pursuit engrossed his
attention until, at last, it had become an absorbing passion.
It was with quite a small telescope, which had been lent him by a
friend, that Herschel commenced his career as an observer. However, he
speedily discovered that to see all he wanted to see, a telescope of
far greater power would be necessary.
He commissioned a friend to procure for him in London a telescope with
high magnifying power. Fortunately for science the price was so great
that it precluded the purchase, and he set himself at work to construct
one. After many trials he succeeded in making a reflecting instrument
of five feet focal length, with which he was able to observe the rings
of Saturn and the satellites of Jupiter.
It was in 1774, when the astronomer was thirty-six years old, that he
obtained his first glimpse of the stars with an instrument of his own
construction. Night after night, as soon as his musical labors were
ended, his telescopes were brought out.
His sister Caroline, who occupies such a distinct place in scientific
history, the same little girl to whom we have already referred, was
his able assistant, and when mathematical work had to be done, she
was ready for it. She had taught herself sufficiently to enable her
to perform the kind of calculations--not, perhaps, very difficult
ones--that Herschel’s work required; indeed, it is not much to say that
the mighty life-work which this man was enabled to perform could never
have been accomplished had it not been for the self-sacrifice of this
ever-loving and faithful sister.
It was not until 1782 that the great achievement took place by which
Herschel at once sprang into fame. He appears to have formed a project
for making a close examination of all the stars above a certain
magnitude for the purpose of discovering, if possible, a parallax among
them. Star after star was brought to the center of the field of view of
his telescope, and after being carefully examined, was then displaced,
while another star was brought forward to be submitted to the same
process.
In the great review which Herschel undertook, he doubtless examined
hundreds, or perhaps thousands of stars, allowing them to pass away
without note or comment. But on an ever-memorable night in March,
1782, it happened that he was pursuing his task among the stars in the
constellation of Gemini. One star was noticed which, to Herschel’s
acute vision, seemed different from the stars which in so many
thousands are strewn over the sky. There was something in the starlike
object that immediately arrested his attention, and made him apply to
it a higher magnifying power. This at once disclosed the fact that the
object possessed a disk--that is, a definite, measurable size--and
that it was thus totally different from any of the hundreds and
thousands of stars which exist elsewhere in space. The organist at the
Octagon Chapel at Bath had discovered a new planet with his home-made
telescope. Great was the astonishment of the scientific world when the
Bath organist announced that the five planets, which had been known
from all antiquity, must now admit the company of a sixth.
The now great astronomer was invited to Windsor, and to bring his
famous telescope in order to exhibit the planet to George III, and
to tell his majesty all about it. The king took so great a fancy to
Herschel that he proposed to confer on him the title of “his majesty’s
own astronomer,” to assign him a residence near Windsor, to provide him
with a salary, and to furnish such funds as might be required for the
erection of great telescopes, and for the conduct of that mighty scheme
of celestial observation on which Herschel was so eager to enter.
No single discovery of Herschel’s later years was, however, of the same
momentous description as that which first brought him to fame. There
is no separate collection of his writings, and very scanty accounts of
his life have been published; but he who has written his name among the
stars needs no other testimonial to his fame. Prior to his time the
number of bodies known as belonging to the Solar System was eighteen,
including secondary planets and Halley’s comet. To these he added nine;
namely, Uranus and six satellites, and two satellites of Saturn.
Though no additional honors could add to his fame, Dr. Herschel, in
1816, received the decoration of the Guelphic Order of Knighthood.
In 1820 he was elected president of the Astronomical Society, and
among their Transactions, the next year, he published an interesting
memoir on the places of one hundred and forty-five double-stars. This
paper was the last which he lived to publish. His health had begun to
decline, and on the 24th of August, 1822, he sank under the infirmities
of age, having completed his eighty-fourth year. He was survived by his
widow, Lady Herschel, an only son, Sir John F. W. Herschel, and his
sister Caroline, who died in 1847, in her ninety-eighth year.
LAPLACE.
The author of “Celestial Mechanics” was born at Beaumont-en-Auge in
1749, just thirteen years later than his renowned friend Lagrange.
His father was a farmer, but appears to have been in a position to
provide a good education for a son who seemed promising. The subject
which first claimed his attention was theology. He was, however, soon
introduced to the study of mathematics, in which he presently became so
proficient that, while he was still no more than eighteen years old, he
obtained employment as a mathematical teacher in his native town.
Desiring wider opportunities for study, young Laplace started for
Paris, being provided with letters of introduction to D’Alembert,
who then occupied the most prominent positions as a mathematician in
France, if not in Europe. On presenting these letters, he seems to have
had no reply; whereupon, Laplace wrote to D’Alembert, submitting a
discussion of some point in dynamics.
This letter instantly produced the desired effect. D’Alembert thought
that such mathematical talent as the young man displayed was in itself
the best of introductions to his favor. It could not be overlooked, and
accordingly he invited Laplace to come and see him. Laplace, of course,
presented himself, and erelong D’Alembert obtained for the rising
philosopher a professorship of Mathematics in the military school in
Paris. This gave the brilliant young mathematician the opening for
which he sought, and he quickly availed himself of it.
Laplace’s most famous work is “Celestial Mechanics,” in which he
essayed a comprehensive attempt to carry out, in much greater detail,
the principles which Newton had laid down. The fact was that Newton
had not only to construct the theory of gravitation, but he had to
invent the mathematical processes by which his theory could be applied
to the explanation of the movements of the heavenly bodies. In the
course of the century which had elapsed between the time of Newton and
the time of Laplace, mathematics had been extensively developed. The
disturbances which one planet exercises upon the rest can only be fully
ascertained by the aid of long calculations, and for these calculations
analytical methods are required.
With an armament of mathematical methods which had been perfected
since the days of Newton by the labors of two or three generations of
mathematical inventors, Laplace essayed in his “Celestial Mechanics”
to unravel the mysteries of the heavens. It will hardly be disputed
that the book which he has produced is one of the most difficult
books to understand that has ever been written. The investigations of
Laplace are, generally speaking, of too technical a character to make
it possible to set forth any account of them in such a work as the
present. He did, however, publish one treatise, called the “System of
the Universe,” in which, without introducing mathematical symbols, he
was able to give a general account of the theories of the celestial
movements, and of the discoveries to which he and others had been led.
In this work Laplace laid down the principles of the nebular theory,
which, in modern days, has been generally accepted.
The nebular theory gives a physical account of the origin of the
Solar System, and has already been explained in this volume. Bach
advance in science seems to make it more certain that this hypothesis
substantially represents the way in which our Solar System has grown to
its present form.
Not satisfied with a career which was merely scientific, Laplace sought
to connect himself with public affairs. Napoleon appreciated his
genius, and desired to enlist him in the service of the state. Laplace
was appointed to the office of minister of the interior. The experiment
was not successful, for he was not by nature a statesman. In despair
of Laplace’s capacity as an administrator, Napoleon declared that he
carried the spirit of his infinitesimal calculus into the management
of business. Indeed, Laplace’s political conduct hardly admits of much
defense. While he accepted the honors which Napoleon showered on him in
the time of his prosperity, he seems to have forgotten all this when
Napoleon could no longer render him service. Laplace was made a marquis
by Louis XVIII. During the latter part of his life the philosopher
lived in a retired country-place at Arcueile. Here he pursued his
studies, and, by strict abstemiousness, preserved himself from many of
the infirmities of old age.
He was endowed with remarkable scientific sagacity; but above all
his powers his wonderful memory shone pre-eminent. His “Celestial
Mechanics” is, next to Newton’s “Principia,” the greatest of
astronomical works.
He died on March 5, 1827, in his seventy-eighth year, his last words
being, “What we know is but little, what we do not know is immense.”
LEVERRIER.
We are apt to identify the idea of an astronomer with that of a man
who looks through a telescope at the stars; but the word astronomer
has really a much wider significance. No man who ever lived has been
more entitled to be designated an astronomer than Urbain Jean Joseph
Leverrier, and yet it is certain that he never made a telescopic
discovery of any kind. In mathematics, however, he excelled, and
he simply used the observations of others as the basis of his
calculations.
These observations form, as it were, the raw material on which the
mathematician exercises his skill. It is for him to elicit from the
observed places the true laws which govern the movements of the
heavenly bodies. Here is indeed a task in which the highest powers of
the human intellect may be worthily employed. To Leverrier it has been
given to provide a superb illustration of the success with which the
mind of man can penetrate the deep things of nature.
The illustrious Frenchman was born on the 11th of March, 1811, at
Saint-Lô, in the department of Manche. In the famous polytechnic
school for education in the higher branches of science he acquired
considerable fame as a mathematician. His labors at school had revealed
to Leverrier that he was endowed with the powers requisite for dealing
with the subtlest instruments of mathematical analysis. When he was
twenty-eight years old his first great astronomical investigation was
brought forth. This was the profound calculation of the disturbances of
the planet Uranus and the causes of them.
The talent which his researches displayed brought Leverrier into
notice. At that time the Paris Observatory was presided over by
Arago, a savant who occupies a distinguished position in French
scientific annals. Arago at once perceived that Leverrier possessed the
qualifications suitable for undertaking a problem of great importance
and difficulty that had begun to force itself on the attention of
astronomers. What this great problem was, and how astonishing was the
solution it received, must now be considered.
Ever since Herschel brought himself into fame by the discovery of
Uranus, the movements of this new addition to the Solar System had been
scrutinized with care and attention. The position of Uranus was thus
accurately determined from time to time. When due allowance was made
for whatever influence the attraction of Jupiter and Saturn and all
the other planets could possibly produce, the movements of Uranus were
still inexplicable. It was perfectly obvious that there must be some
other influence at work besides that which could be attributed to the
planets already known.
Astronomers could only recognize one solution of such a difficulty.
It was impossible to doubt that there must be some other planet in
addition to the bodies at that time known, and that the perturbations
of Uranus, hitherto unaccounted for, were due to the disturbances
caused by the action of this unknown planet. Arago urged Leverrier
to undertake the great problem of searching for this body. But the
conditions of the search were such that it must be conducted on
principles wholly different from any search which had ever before been
undertaken for a celestial object. For this was not a case in which
mere survey with a telescope might be expected to lead to the discovery.
There are in the heavens many millions of stars, and the problem of
identifying the planet, if indeed it should lie among these stars,
seemed a very complex matter. Of course, it is the abundant presence of
the stars which causes the difficulty.
The materials available to the mathematician for the solution of
this problem were to be derived solely from the discrepancies between
the calculated places in which Uranus should be found, taking into
account the known causes of disturbances, and the actual places in
which observation had shown the planet to exist. Here was, indeed, an
unprecedented problem, and one of extraordinary difficulty. Leverrier,
however, faced it, and, to the astonishment of the world, succeeded in
carrying it through to a brilliant solution.
After many trials, Leverrier ascertained that, by assuming a certain
size, shape, and position for the unknown planet’s orbit, and a certain
value for the mass of the hypothetical body, it would be possible
to account for the observed disturbances of Uranus. Gradually it
became clear to his perception, not only that the difficulties in
the movements of Uranus could be thus explained, but that no other
explanation need be sought for. And now for an episode in this history
which will be celebrated so long as science shall endure. It is nothing
less than the telescopic confirmation of the existence of this new
planet, which had previously been indicated only by mathematical
calculation.
Great indeed was the admiration of the scientific world at this superb
triumph. Here was a mighty planet, whose very existence was revealed by
the indications afforded by refined mathematical calculation. At once
the name of Leverrier, already known to those conversant with the more
profound branches of astronomy, became everywhere celebrated.
When, in 1854, Arago’s place had to be filled at the head of the great
Paris Observatory, it was universally felt that the discoverer of
Neptune was the suitable man to assume the office. Leverrier died on
Sunday, September 23, 1877, in his sixty-seventh year.
* * * * *
FREDERICK WILLIAM BESSEL was born at Minden in 1784, and early turned
his attention to mathematical subjects. He devoted himself with
ardor to astronomy, and in 1804 he undertook the reduction of the
observations made on the comet of 1607. His results were communicated
to Olbers, who warmly praised the young astronomer, and in 1806
recommended him to Schroeter as an assistant in the observatory of
Lilienthal. In 1810 he was appointed director of the new observatory
then being founded by the king at Königsberg. He was admirably fitted
for this post, and is distinguished mainly for his discovery of the
parallax of the star 61 Cygni, which he accomplished by methods of
extreme ingenuity and delicacy.
Two kinds of telescopes are commonly used, the refractor and the
reflector. The first telescopes made were all refractors, and the very
first of them was made, as you know, by Galileo. The first reflector
was made in later days by Sir Isaac Newton.
In a refractor the rays of light, from a star or any other bright
body, reach first a large object-glass, through which they pass, and
by which, as they pass, they are caused to converge, narrowing to a
focus or point. From this point they widen slightly on their way to the
eye-piece. After passing through the eye-piece, by which they are once
more straightened into parallel rays, they arrive at the eye.
Speaking broadly, the eye receives--actually sees--nearly as much of
the starlight as if its pupil were the full size of the object-glass
of that telescope, and the power of such an instrument depends upon
the size of the object-glass. A refractor has been made with an
object-glass forty inches across, and this, for the observer, means
looking at a star with an eye pupil more than three feet in diameter.
This refractor is now in the Yerkes Observatory at Williams Bay, Lake
Geneva, Wisconsin.
There are several forms of reflectors. With one form, when it is
pointed at a star, the rays of starlight fall direct through the
telescope-tube upon a highly-polished mirror, so shaped that rays of
light reflected thence are caused to fall converging upon a small
plane-mirror in the center of the tube, from which they are thrown,
parallel to the side of the tube, to the eye-piece, which converges
them to the eye.
The mirror of a reflector can be made very much larger than the
object-glass of a refractor. The famous Lord Rosse telescope, which
has a tube sixty feet long, contains a mirror no less than six feet in
diameter. This, to an observer, is tantamount to looking at the stars
with an eye so huge that its pupil alone would be nearly equal in size
to the six-foot wheel of a steam-engine. It will readily be perceived
how much more starlight can be grasped by such a fishing-net than by
the tiny pupil of your eye or mine.
A main difference between the two kinds of telescope thus resides in
the fact that the star-rays--or any other kind of light-rays--when
first captured, pass, in one case, _through_ the glass on which they
fall, and, in the other case, are thrown off _from_ the mirror. In both
cases, the whole amount of light so captured is gathered into a small
compass, so as to be available for human sight.
[Illustration: EYE-PIECE OF THE LICK TELESCOPE.]
Once more, let me remind you, it should be always kept clearly in
mind that every object that is seen by us--from a mote of dust to a
sun, from a coal-scuttle to a star--is perceived purely and solely by
the light which it gives out, either intrinsic or reflected light.
Countless myriads of rays pass from the surface of the thing seen to
our eyes, picturing there, on the sensitive retina, a fleeting vision
of its form.
All the leading Governments in Europe have observatories for the study
of the heavens, which are furnished with the best instruments of modern
construction. The principal observatories are those at Paris, Berlin,
Vienna, Nice; Dorpat, the seat of a celebrated university founded by
Gustavus Adolphus, of Sweden, in 1630; Pulkowa, near St. Petersburg;
Lisbon, and at Greenwich in England. In America, though only in recent
years has astronomy been cultivated with ardor, there are observatories
of more or less importance,--the National Observatory at Washington,
D. C.; the Cincinnati Observatory, projected by the late General O. M.
Mitchel; the Dudley Observatory, founded by Mrs. Blandina Dudley in
honor of her husband, at Albany, N. Y.; the Lick Observatory, founded
by James Lick, on Mount Hamilton, Cal.; and the Yerkes Observatory,
connected with the Chicago University, founded by Charles T. Yerkes.
Besides these, there are observatories connected with some of our other
leading universities and colleges, as those of Harvard, at Cambridge,
Mass.; Yale University; Williams College; West Point Military Academy;
Amherst College; Princeton; Dartmouth; Michigan University; Hamilton
College, N. Y., and several others.
[Illustration: LICK OBSERVATORY IN WINTER, FROM THE EAST.]
The largest and best refracting telescopes in the world are those
at Lick Observatory and at Yerkes Observatory, now in charge
of Professor E. E. Barnard, who, while at the head of the Lick
Observatory, discovered the fifth satellite of Jupiter, and determined
the character of the inner ring of Saturn. The best reflecting
telescope is that of Lord Rosse, at Birr Castle, in Kings County,
Ireland.
[Illustration: E. E. BARNARD.]
In reviewing the path which we have traversed in this volume, though we
have penetrated the sidereal depths and wandered at will through space,
we feel that we have not yet reached the outskirts of creation. We
have never left the center. Beyond us still lies the circumference. We
see opened before us the infinite, of which the study is not yet begun!
We have seen nothing; we recoil in terror; we fall back astounded.
Indeed, we might fall into the yawning abyss--fall forever, during a
whole eternity; never, never should we reach the bottom, any more than
we have attained the summit. There is no east nor west, neither right
nor left. There is no up nor down; there is neither a zenith nor a
nadir. In whatever way we look, it is infinite in all directions.
In this infinitude of space, the associations of suns and of worlds
which constitute our visible universe form but an island, a vast
archipelago; and in the eternity of duration, the life of our proud
humanity, with all its concerns, its aspirations, and its achievements,
the whole life of our entire planet, is but the shadow of a dream! Well
might the Hebrew poet, as he looked forth upon nature, exclaim in his
amazement: “When I consider thy heavens, the work of thy fingers, the
moon and the stars which thou hast ordained, what is man that thou art
mindful of him, and the son of man that thou visitest him?”
The constellations, the charts of the sky; the catalogues of curious
stars--variable, double or multiple, and colored; the description of
instruments accessible to the observer of the heavens, and useful
tables to consult, are only touched upon in this volume. The reader
whose scientific desires are satisfied by the elements of astronomy,
may stop here. Few have time to pursue the subject further; but it is
sweet to live in the sphere of the mind; it is sweet to contemn the
rough noises of a vulgar world; it is sweet to soar in the ethereal
heights, and to devote the best moments of our life to the study of the
true, the infinite, and the eternal!
PUBLISHERS’ NOTE.
We have now reached the conclusion of “The Story of the Sun, Moon,
and Stars.” Miss Giberne’s work has been supplemented with a large
amount of matter from other sources. The value of the book has thus
been increased without diminishing its popular character. In most
admirable form it tells the story of the heavenly world, which is the
work of God’s hands, the moon and the stars which he has made. The
reverent reader, to whom the Word of God is “sweeter than honey and
the honey-comb,” may here find that “the heavens declare the glory of
God, and the firmament showeth his handiwork.” We confidently present
it to the reader as the best and completest work in print on the great
subject of which it treats.
INDEX
Adams, John Couch, 231, 236
Aërolites, 84
Size of, 86
Aldebaran, Movement of, 277
Alexander at Arbela, 146
Alpha Centauri, Distance of, 99
Duration of light journey, 102
Position, 279
Alps, Lunar Mountains, 179
Altai, Lunar Mountains, 179
Andromeda, Constellation of, 112
Apennines, Lunar Mountains, 179
Arago, 235, 402
Arcturus, Motion of, 114
Position, 276
Aristotle, 376
Asteroids, 53
Astronomy, The dawn of, 363
Attraction, 34
Aurora Borealis, where seen, 141
Axis of earth slanting, 44
Barnard, E. E., 53, 410
Bessel, F. W., 284
Discovery of star parallax, 324
Discovers star parallax, 405
Bolides, 87, 257
Borelli, 388
Capella, Duration of light journey, 103
Velocity of motion, 114
Caucasian Range, Lunar Mountains, 179
Carpathian, Lunar Mountains, 179
Carrington, 141
Cassini, Measurement of sun’s distance, 310
Cassiopeia, Constellation of, 112
Ceres, size of, 53
Chaldean star-gazers, 365
Chinese records of eclipses, 365
Cicero, 177
Clark, Alvan Graham, 289
Cloven-disk theory, 331
Coal sack, 329
Columbus in Jamaica, 146
Comet, Biela’s, 90, 93
Halley’s, 78, 248
Of 1843, 80
Newton’s, 78
With two tails, 77
Encke’s, 78
Heat endured by, 81
Length of tail, 81
Collision with, 82
Split in two, 91
Comets, 73, 240, 246
Number of, 75
Nature of, 74
Captured by Jupiter, 213
Composition of, 256
Composition of tails, 253
Orbits of, 129
With closed orbits, 76
Confucius as an astronomer, 365
Constellations, Grouping, 366
When named, 366
Copernicus, Author of “Celestial Spheres,” 177, 183, 370, 371, 375
Star parallax, 319
Copernican system of the universe, 175
Corona, Description of, 153
D’Alembert, 399
Dante, 121
Demos, Satellite of Mars, 191
Donati’s Comet, 248, 250
Draco, Constellation of, 112
Earth, Globular, 17
How formed, 21
Member of the Solar System, 14
In motion, 16
Motions, 18, 41, 126
One of a family, 14
Size of, 26
What is it? 13
Ecliptic, 43
Eclipses omens of evil, 145
Egyptian astronomers, 365
Encke, 238
Epicycles, 373
Equinox, 44
Fire-balls, Speed of, 88
Fabricius discovers sun-spots, 27
Fraunhofer, Joseph von, 345
Galle, 232, 238
Galileo, 28, 276, 371, 376, 378, 380
Gassendi, 184
George III, 226
Gilbert, 388
Great Bear, Constellation of, 108, 340
Halley, 388
Transit of Venus, 314
Star motions, 318
Hercules, Constellation of, 112
Herschel, Caroline, 226, 393
Herschel, Sir John, 81, 233, 303, 398
Herschel, William, 96, 119, 225, 271, 393
Hipparchus, 368, 371
Hodgson, 141
Holland, Sir Henry, 237
Hook, Robert, 388
Horrocks, 388
Huggins, Dr., 359
Humboldt, Alexander von, 265
Jupiter, 55
Comparative size, 56
Distance of, 122
His satellites, 56, 206, 210
Velocity, 199
Wind storms, 204
Kepler, 75, 296
Laws of, 371, 374, 380, 388
Kew Observatory, 141
Lacaille, Catalogue of, 105
Lalande, Catalogue of, 105
Laplace, 385, 398
Later astronomy, 393
Leverrier, Urbain J. J., 231, 401
Discovers Neptune, 321
Light, Rapidity of, 101
Time, Duration of, 331
Lowe at Santander, 147
Lunar craters, Antiquity of, 172
How formed, 173
Plato and Copernicus, 173
Ptolemy, 174
Schickard, 174
Tycho, 174
Lunar Mountains, How formed, 174
Lyra, Constellation, 297
Magellanic clouds, 309
Magnetism, 140, 141
Mars, 52, 373, 374
Moons of, 191
Continents of, 197
Distance from earth, 197
Maury, Lieutenant, 80
Mercury, Atmosphere, 181
Distance from sun, 49
Length of year, 180
Is it inhabited? 181
Orbit of, 180
Phases, 50
Size of, 49
Transit of, 184
Meteor, 84, 257
Meteorites, 240, 257
Around the sun, 94
August system, 90, 242
In Saturn’s rings, 94
November system, 90, 94, 241
Number of, 86
Protection from, 86
Shower of 1872, 92
Shower of 1885, 93
Milky Way, 270, 329
Mizar, 342
Modern Astronomy, 375
Moon, 62
Appearance at its full, 63
Atmosphere, 157, 169
Phases of, 160
Condition of, 65
Craters, 68, 170
Earth’s satellite, 164
Earth-shine, 160
Eclipse, 163
Influence on tides, 167
Landscape of, 68
Mountains, 67
Orbit of, 166
Temperature on, 72
Revolution, 64
Size of, 64
Surface, 67
Nasmyth, 173
Nebulæ, Number of, 336
Neptune, 59
Discovery of, 232, 234
Distance of, 123
Length of year, 59
Newton analyzes light, 385
Birth and childhood, 382
Nicetos of Syracuse, 177
Nicias, Athenian General, 146
Nicolas, Cardinal, 177
Observatories, 408
Orbits, Planetary, 47
Orion, Constellation of, 112
Parallax, 311
Phobos, Satellite of Mars, 191
Photography, Stellar, 355
Pius IX, 93
Pisa, Leaning Tower of, 378
Plane of the Ecliptic, 201
Planets, Distance from the sun, 123
First group, 48
How formed, 22
Length of years, 49
Orbits, 47
Order of formation, 23
Second group, 48,55
Plutarch, 177
Pole star, Duration of light journey, 103
Position, 108
Rate of motion, 115
Prism, 344
Pritchard, C., 356
Ptolemaic system of the universe, 175, 369
Ptolemy, 371, 369
Pythagoras, Grecian astronomer, 367
Rosse, Lord, Telescope, 406
Rowton siderite, 258
Saturn, 57
Composition of rings, 221
Distance of, 122
Distance from sun, 214
Length of year, 57
Moons, 217
Rings, 219
Satellites, 58
Size, 214
Weight, 214
Shickard, Crater on the moon, 174
Scheiner, 28
Secchi, 92
Shooting stars, 84
Sirius, Brightness of, 275, 285
Changing color, 285
Distance of, 100
Duration of light journey, 103
Movement of, 277
Solar cloud, 148
Solar System, 60, 122
Model of, 60
Spectroscope, 143, 345
Spectroscopic photography, 360
Spectrum analysis, 346, 354
Star clusters, 304, 336
Parallax, 284, 316
Spectroscopy, 356
Stars, Apparent motion, 107
Attraction, 21
Distance of, 99, 310, 320
Distance, 281, 282
Fixed, Why so called, 20
Fixed, Why, 366
Golden, 274
Magnitude of, 97
How many visible, 95
Measurement, 278
Red, 274
Variable, 274, 291
White, 274
Sun, 24
Attraction of, 156
Attraction of gravitation, 34
Chromatosphere, 32
Cyclones of 30, 136
Density, 26
Destination, 119
Distance of, 25
Eclipse of, 143
Flames, Their height, 31, 151
Flames, Their velocity, 138
Forces and influences, 39
Head of our family, 24
Magnetic power of, 139
Its mottled appearance, 142
Rate of motion, 119
Penumbra, 133
Photosphere, 31, 134
Power of, 39, 137
Rapidity of motion, 26
Revolution on axis, 28
Size, 26, 154
Solar prominence, 32
Spots, 27, 30, 133
Symbol of purity, 380
Umbra, 133
Weight, 27, 154
Swift, Voyage to Laputa, 194
Telescopes, 378, 379, 405
Refractors and reflectors, 405, 408, 410
Tides, 168
Thales, founder of Grecian Astronomy, 367
Toucan, 306
Tycho Brahe, 175, 371, 372, 373
Universe, Definition of, 19
Uranus, 58
Discovery of, 225
Distance of, 123
Venus, Orbit of 51
Is it inhabited? 189
Distance from earth, 186
Phases of, 51, 379
Transits of, 185
Vesta, Size of, 53
Voltaire, Prophecy of, 193
Wilson, 30
Wollaston, Dr. W. H., 345
Wren, 388
Yerkes Observatory, 406
Young, Chas. A., 142, 148
Zodiacal Light, 94, 224, 265
Transcriber's Notes:
In the original a link to Sir Isaac Newton was omitted from the
List of Illustrations. The transcriber has inserted one.
Italics are shown thus: _sloping_.
Variations in spelling and hyphenation are retained.
Perceived typographical errors have been changed.