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.