Part 2
“Kepler was not merely an observer and calculator; he inquired with great diligence into the physical causes of every phenomenon, and made a near approach to the discovery of that great principle which maintains and regulates the planetary motions. He possessed some very sound and accurate notions of the nature of gravity, but unfortunately conceived it to diminish simply in proportion to the distance, although he had demonstrated that the intensity of light is reciprocally proportional to the surface over which it is spread, or inversely as the square of the distance from the luminous body.”
Great names follow in rapid succession. One of Kepler’s contemporaries was Galileo Galilei, the discoverer of the “three laws of motion” and the relation of time and space in falling bodies, the first to apply the newly invented telescope to the observation of the heavens and the discoverer of four satellites of Jupiter (named by him the “Medeiran Stars” in honor of his patron). He also detected spots on the sun’s disk, the phases of Venus, and irregularities on the moon’s surface, and declared the Milky Way to be composed of a countless tract of separate stars.
When we remember the limited power of the telescope of the age, we can but marvel, not at how little, but how much was known regarding the starry skies.
During this period, numerous observers rendered great service to Astronomy, and other scientists were engaged in making useful drawings, charts, maps, tables, and catalogues of stars.
To this period also belongs John Bayer of Augsburg, who published a description of the constellations with maps upon which the stars were marked with the letters of the Greek Alphabet—a convenient method that was universally adopted and is still in use. Other names include Gassendi, Riccioli, Grimaldi, and Hevelius—the latter a rich citizen of Dantzig, who had a fine observatory of his own, where he worked for forty years. His drawings and descriptions of the moon, his researches on comets, which he still believed moved in parabolas, and his celestial charts engaged most of his attention.
The Dutch astronomer Huygens (born in 1629) is famous for his improvements in the telescope use of the pendulum clock and developments in the machinery of astronomical instruments. He discovered the ring of Saturn and four of his satellites. Edmund Halley, an English astronomer (born in 1656), also took a great interest in the telescope, and went to Dantzig to settle a controversy between Robert Hooke and Hevelius regarding the best glasses for use in astronomical observations; for Hevelius still worked with the ancient instruments, while Hooke believed in the lens.
Halley revived the ancient idea that comets belonged to the Solar System, and predicted that the comet of 1681 would return to its perihelion in 1759. This was the first prediction of its kind verified.
During the last quarter of the Seventeenth Century, the telescope assumes importance and two great observatories begin their work. In 1670 the Paris Observatory, of which Cassini was made director, was finished, and five years later the Greenwich Observatory, where Flamsteed was installed as royal astronomer.
Of Cassini, Lalande remarks that under him Astronomy underwent revolutions, and in France he was regarded as the “creator of the science.” Cassini discovered that Saturn’s ring was double and found four satellites of Jupiter.
Flamsteed’s observations on planets, satellites, comets, “fixed stars,” and his catalogue of 2,884 stars were valuable contributions to science; and his _Historia Cœlestis_ is said to have “formed a new era in sidereal astronomy.”
Flamsteed was succeeded by Halley, particularly famed for his investigations of comets. The next great astronomical event was the discovery of Uranus by Sir William Herschel in 1781. Sir William Herschel also discovered two more of Saturn’s satellites, and began the great work of resolving the Milky Way and other clusters into swarms of suns, single stars into double and triple stars, inquiries into the mysteries of the nebulæ, and in every way enlarging the general conception of the sidereal universe.
To the end of the Eighteenth and beginning of the Nineteenth Centuries belongs the brilliant French astronomer and mathematician Laplace, who published in 1799-1808 his _Mécanique Céleste_, in which he announced his Nebular Hypothesis (described on page 433 of Vol. II. The discoveries of the Planetoids are described on pages 396-403, and that of Neptune in 1846 on pages 430-432). The latest important additions to the Solar System are the discovery by Prof. Barnard of Jupiter’s Fifth Satellite in 1892 and Saturn’s Ninth by Prof. W. H. Pickering in 1904. The discovery even of a Seventh Satellite of Jupiter has just been announced from the Lick Observatory.
It would be impossible to mention the names of the astronomers whose work from the middle of the last century to its closing years has been distinguished in various fields. Space only permits brief mention of the new methods of research by means of the spectroscope and celestial photography. With the first the name of the English astronomer, William Huggins, is identified and has yielded most important and startling information regarding the composition of heavenly bodies, and with the application of the photographic telescope these new methods have created a revolution in astronomical observation.
It may be interesting to gain a slight idea of the numbers of stars revealed by the camera by referring to Sir Robert Ball:
“If we take a position on the equator, from whence, of course, all the heavens can be completely seen in the lapse of six months, the number of stars that can be reckoned with the unaided eye will, according to Houzeau, amount to about six thousand. If we augment our unaided vision by a telescope of even small dimensions, such as three inches in diameter, the number of stars in the Northern Hemisphere alone is upward of three hundred thousand. We may assume that the Southern Hemisphere has an equally numerous star-population, so that the entire multitude visible with this optical aid is about six hundred thousand. Thus we see that the use of a telescope small enough to be carried in the hands suffices to multiply the lucid stars one-hundredfold. Great telescopes no doubt soon show us that the hundreds of thousands are only the brighter members of a host of millions, and now we receive the assurance of photography that the telescopic stars are only the more conspicuous members of that vast universe. Mr. Roberts indeed declares that the multitudes of stars on the photographic plate grow with each increase of exposure to such a degree that it would almost seem as if the plate would be a wellnigh continuous mass of stars if the operations could be sufficiently protracted.”
Naturally the past years have witnessed the making of new catalogues and maps of stars, and many valuable computations of parallaxes, etc. Some of the results obtained by these new methods are described in the chapters on the Nebulæ and Swarms of Suns, The Great Nebula of Orion, and The Colored, Double, Multiple, Binary, Variable, and Temporary Stars in Vol. I. From this brief survey of the progress of Astronomy the fact will be appreciated, therefore, that all the discoveries and researches have resulted in a larger conception of the universe, and the Solar System sinks into insignificance in the vast ocean of stars and suns.
The study of the Earth’s crust and its contents divested of superstition dates from the end of the Seventeenth Century. Nicolaus Steno (1638-1687), a Dane, devoted himself to geology, and in 1669 observed successive layers of strata. He is called “the father of Palæontology.” In 1680 Leibnitz proposed the theory that the Earth was originally in a molten state. The classification of strata was begun about the middle of the Eighteenth Century. The views of James Hutton (1788), who returned to the theories advanced by Ray (a return to the views of Pythagoras), were continued by Sir Charles Lyell.
Geology and Palæontology have progressed side by side. Among the most famous investigators are Cuvier, Dawson, Marsh, Owen, Huxley, Agassiz, De Blainville, Kaup, Sir Roderick Murchison, Boyd Dawkins, Sir William Flower, R. Lydekker, and E. D. Cope.
To the review of the new developments of meteorology and the science of probabilities by Sir Ralph Abercromby, on pages 784-792 of Vol. II, it is only necessary to add that the interest in meteorological research developed greatly after Torricelli’s discovery in 1643 of weight and pressure in the atmosphere led to the perfection of the barometer and the development of the thermometer and hygrometer, both in the Seventeenth Century. The theory of trade-winds George Hadley announced in the _Philosophical Transactions_ for 1735. Dalton’s _Meteorological Essays_, published in 1793, and Dr. William Charles Wells’s _Theory of Dew_, published in 1814, attracted much attention. Regarding the inquiries into the laws of light by Snell, Newton, Descartes, Thomas Young, and Sir George Airy, the reader is referred to the chapter on The Rainbow in Vol. II, by John Tyndall, with whose researches in the latter half of the Nineteenth Century every one is more or less acquainted.
Little need be said here regarding the history of Botany, which is reviewed on pages 984-1000 of Vol. II. We may add, however, that one of the first to revive this study was Otto Brunsfels, whose _Historia Plantarum Argentorati_ was published in two folio volumes with cuts in Strasburg in 1530. He had many followers on the Continent and in England. During the revival of learning, chairs of Botany were founded in the universities; botanic gardens were established in many places (the Jardin des Plantes was founded in 1626); and botanists began to travel to remote countries to search for unknown flora.
To the Seventeenth Century belong the names of Dr. Turner, “the father of English Botany”; Robert Morison, professor of Botany at Oxford; John Ray, Nehemiah Grew, Malpighi, Henshaw, and Robert Hooke. The two latter were among the first to employ the newly invented microscope to the study of this science. It may be mentioned in passing, that Huygens is said to have taken from Holland to England microscopes about the size of a grain of sand, and that the first microscope consisting of a combination of lenses is attributed to Jansen, a spectacle-maker of Holland. Hooke, whom Herschel calls “the great contemporary and almost the rival of Newton,” gave a tremendous impetus to Microscopy, and practically laid the foundation of Histology or the Inner Morphology of Plants, due to Grew and Malpighi. Schleiden undertook to explain the mysteries of cell formation in 1838, further investigated by Schwann, and is now known as the Schleiden-Schwann theory. Nägeli and Von Mohl continued researches on this line. To the contents of the cell Von Mohl gave the name _protoplasm_.
In 1849, Hofmeister began investigations into the life-histories of plants, since when the study of Vegetable Physiology has progressed side by side with Chemistry. To Darwin great subjects are due: the cross-fertilization of plants, their reproduction, and their relations to insects and their movements. It may be mentioned, however, that in 1693 Ray attempted to explain the movements of leaves, tendrils, and petals by physical and mechanical laws.
Since the middle of the Nineteenth Century, the branches of Botany that have been particularly studied are Vegetable Physiology and Pathology, Inner Morphology, and Fossil Botany—and the discoveries made have naturally had an effect upon the classification of vegetable life.
According to Agassiz:
“We must come down to the last century, to Linnæus, before we find the history taken up where Aristotle had left it, and some of his suggestions carried out with new freshness and vigor. Aristotle had already distinguished between genera and species; Linnæus took hold of this idea, and gave special names to other groups, of different weight and value. Besides species and genera, he gives us orders and classes—considering classes the most comprehensive, then orders, then genera, then species. He did not, however, represent these groups as distinguished by their nature, but only by their range; they were still to him, as genera and species had been to Aristotle, only larger or smaller groups, not founded upon and limited by different categories of structure. He divided the animal kingdom into six classes: Mammalia, Birds, Reptiles, Fishes, Insects, and Worms.”
Linnæus’s classification was, therefore, the first attempt to group animals; but until Cuvier there was no great principle of classification. In 1707 Buffon succeeded in making Zoology, which had been regarded as a most uninteresting study, popular and respected. He also had the idea of collecting all the known facts of scientific investigation and arranging them systematically. Buffon was ridiculed as a scientist by his contemporaries, Hevelius, Diderot, D’Alembert, and Condillac, who opposed his explanations of natural phenomena. Buffon’s _Histoire Naturelle Générale et Particulière_ is his most important work. A complete edition in thirty-six volumes appeared in Paris in 1749-1788. Although it is said to “have made an epoch in the study of the natural sciences” in Buffon’s day, it now possesses little scientific value.
Cuvier’s classification has never been overthrown. His original investigations in various departments of science, and particularly that of fossil vertebrate animals, opened up new fields of study. His talents with both pen and pencil contributed largely to making that branch of science popular.
Lamarck, Cuvier’s contemporary, divided the animal kingdom into Vertebrates and Invertebrates. Lamarck, like Geoffroy Saint-Hilaire, was a believer in the theory of evolution, which was opposed by Cuvier.
Lamarck turned from the study of Meteorology to that of Botany, and later again to that of Zoology. In 1793 he became professor of the natural history of the lower classes of animals in the Jardin des Plantes. His theories have greatly influenced modern science,
## particularly that of the “Variation of Species,” which was set forth
in his _Philosophie Zoologique_ (two vols., Paris, 1809) and other works. Lamarck’s _Histoire des Animaux sans Vertèbres_ (seven vols., Paris, 1815-22) is his greatest work.
Karl Ernst von Baer, the Russian naturalist, a pupil of Döllinger in Würzburg, devoted himself chiefly to the study of embryology and made valuable discoveries.
Passing by many illustrious names, we come to that of Sir Richard Owen, of whom it has been said that “from the sponge to man, he has thrown light over every subject he has touched.” His work in the Hunter Museum, his descriptions and restorations of extinct birds and animals, and his original works on every branch of animal life, form an enormous contribution to the progress of science. He promulgated the advanced views of John Hunter, the great physiologist and surgeon, of whose famous museum of more than ten thousand specimens, illustrative of anatomy and natural history, he became curator.
Three names shine with especial lustre upon the Nineteenth Century—Darwin, Huxley, and Spencer. The theory of evolution first appeared in De Maillet’s work, _Telliamed_, published in 1758, but written in 1735. More than thirty writers before Darwin treated this theory, among whom were Erasmus Darwin, Goethe, Lamarck, and Geoffroy Saint-Hilaire. Largely owing to the opposition of Cuvier, it never succeeded until it was revived by Charles Darwin, who, after twenty-one years of work, published his results in 1858 in the _Journal of the Linnæan Society_, followed in the next year by _The Origin of Species by Means of Natural Selection_ (see pages 1482-1512 of Vol. IV).
“The lifeless earth,” says Sir Robert Ball, “is the canvas on which has been drawn the noblest picture that modern science has produced. It is Darwin who has drawn this picture. He has shown that the evolution of the lifeless earth from the nebula is but the prelude to an organic evolution of still greater interest and complexity. He has taken up the history of the earth at the point where the astronomer left it, and he has made discoveries which have influenced thought and opinion more than any other discoveries that have been made for centuries.”
The neglected department of Marine Zoology the Nineteenth Century has made particularly its mission to investigate, but space only permits mention of four names: Edward Forbes, Lord Kelvin (Sir Wyville Thomson), Ernst Heinrich Haeckel, and the Prince of Monaco.
The first, whom Lord Kelvin considers “the most accomplished and original naturalist of his time,” was a pupil of Geoffroy Saint-Hilaire, Jussieu, and De Blainville. He is regarded as the originator of the use of the dredge for collecting specimens and the first who undertook the systematic study of Marine Zoology with reference to the distribution of fauna. In 1859 his _Natural History of the European Seas_ appeared after his death.
One of the most important investigators in this line is Prof. Haeckel, famous for his studies of the lower class of marine animals. He is also distinguished for his researches in other branches of Zoology and Palæontology, and was one of the first followers of Darwin in Germany.
Entomology has also made enormous progress during the Nineteenth Century. At the end of the Seventeenth Century, Ray estimated the number of insects throughout the world at 10,000 species! The great entomologists of the Eighteenth Century include Linnæus, De Geer, and Fabricius. Next follow Latreille, Kirby and Spence, and a host of distinguished scientists in Europe and the United States, of whom Sir John Lubbock (Lord Avebury) heads the list. A comparatively new line of investigation is that of the Chalcididæ (see Fairy Flies, pages 1449-1458, in Vol. IV).
ESTHER SINGLETON.
ILLUSTRATIONS
The Zodiacal Light _Frontispiece_
Chart of the Northern Constellations _Opposite p._ 73
Belt and Sword of Orion ” 121
Nebula in the Constellation Cygnus ” 169
Sun’s Surface and Sun Spot ” 217
Portion of the Moon’s Disk ” 265
Nine Views of the Hour-Glass Sea on Mars ” 313
Twelve Views of Jupiter ” 361
Three Views of Saturn ” 409
CONTENTS
THE HEAVENS. Amédée Guillemin 25
SPACE. Richard A. Proctor 33
EXTENT OF THE SIDEREAL HEAVENS. Sir Robert S. Ball 42
THE STARS. Amédée Guillemin 53
THE LUCID STARS. J. E. Gore 60
THE CONSTELLATIONS. Camille Flammarion 70
THE ARABIAN HEAVENS. Ludwig Ideler 106
ASTRONOMY WITHOUT A TELESCOPE. J. E. Gore 120
THE MILKY WAY. Richard A. Proctor 133
THE MAGELLANIC CLOUDS—ZODIACAL LIGHT—STAR GROUPS. Amédée Guillemin 147
THE NEBULÆ AND SWARMS OF SUNS. J. E. Gore 154
THE GREAT NEBULA OF ORION. Sir Robert S. Ball 176
COLORED, DOUBLE, MULTIPLE, BINARY, VARIABLE, AND TEMPORARY STARS. J. E. Gore 187
A WORLD ON FIRE—NOVA PERSEI. Alexander W. Roberts 228
TELESCOPES. A. Fowler 238
METEORS. Sir Robert S. Ball 266
COMETS. Sir John Herschel 282
LIFE IN OTHER WORLDS. J. E. Gore 307
THE SUN—WHAT WE LEARN FROM IT. Richard A. Proctor 316
MERCURY. William F. Denning 353
THE PLANET VENUS. Camille Flammarion 358
THE EARTH AS A PLANET. Élisée Réclus 364
THE MOON. Thomas Gwyn Elger 376
MARS. Agnes M. Clerke 385
THE PLANETOIDS. Camille Flammarion 396
JUPITER. Agnes M. Clerke 403
SATURN. Agnes M. Clerke 415
URANUS AND NEPTUNE. William F. Denning 426
THE STORY OF THE UNIVERSE
THE HEAVENS.—AMÉDÉE GUILLEMIN
What are the heavens? Where the shores of that limitless ocean; where the bottom of that unfathomable abyss?
What are those brilliant points—those innumerable stars, which, never dim, shine out unceasingly from the dark profound? Are they sown broadcast—orderless, with no other bond save that which perspective lends to them? Or, if not immovable, as we have so long imagined, if not golden nails fixed to a crystal vault, whither are they bound? And, finally, what are the parts assigned to the sun, our earth, and all the earths attendant on the glorious orb of day in this tremendous concert of celestial spheres—this sublime harmony of the universe?
These are magnificent problems of which the most fertile imagination would have in vain attempted the solution, if, for the greater glory of the human mind, astronomy—first born of the sciences—had not at length come to our aid.
How wonderful is the power of man! Chained down to the surface of the earth, an intelligent atom on a grain of sand lost in the immensity of a space, he invents instruments which multiply a thousand-fold his vision, he sounds the depths of the ether, gauges the visible universe, and counts the myriads of stars which people it; next, studying their most complicated movements, he measures exactly their dimensions and the distances of the nearest of them from the earth, and next deduces their masses; then, discovering in the seeming disorder of the stellar groupings real bonds of union, he at last evolves order from apparent confusion.
Nor is this all. Rising by a supreme flight of thought to the most abstract speculations, he discovers the laws which regulate all celestial movements, and defines the nature of the universal force which sustains the worlds.
Such are the fruits of the unceasing labors of twenty generations of astronomers. Such the result of the genius and of the patient perseverance of men who have devoted themselves for two thousand years to the study of the phenomena of the heavens. The Chaldean shepherds were, they say, the first astronomers. We can well believe it. Dwelling in the midst of vast plains, where the mildness of the seasons permitted them to pass the night in the open air, where the clear sky unfolded before them perpetually the most glorious scenes, they ought to have been, and they were, contemplative astronomers. And all of us would be what they were did not the rigor of our climate and our variable atmosphere so often prevent us observing the heavens; and did not, moreover, the turmoil and cares of civilized life deprive us of the necessary leisure.
Nothing is more fitted to elevate the mind toward the infinite than the pensive contemplation of the starry vault in the silent calm of night. A thousand fires sparkle in all parts of the sombre azure of the sky. Varied in color and brilliancy, some shine with a vivid light, perpetually changing and twinkling; others, again, with a more constant one—more tranquil and soft; while very many only send us their rays intermittently, as if they could scarce pierce the profundity of space.
To enjoy this spectacle in all its magnificence, a night must be chosen when the atmosphere is perfectly pure and transparent—one neither illuminated by the moon, nor by the glimmer of twilight or of dawn. The heavens then resemble an immense sea, the broad expanse of which glitters with gold dust or diamonds.
In presence of such splendor, the senses, mind and imagination are alike inthralled. The impression gathered is an emotion at once profound and religious, an indefinable mixture of admiration, and of calm and tender melancholy. It seems as if these distant worlds, in shining earthward, put themselves in close communication with our thoughts.
At a first glance at the starry firmament the stars seem pretty regularly distributed; nevertheless, look at that whitish, undecided, vapory glimmer which girdles the heavens as with a belt. It is the Milky Way.[1] As we approach the borders of this star-cloud in our inspection, the stars appear more and more crowded together, and most of them so small that the eye can scarcely distinguish them. The accumulation of stars in the direction of the Milky Way is more especially visible when we examine the heavens with the aid of a powerful telescope.
The Milky Way itself is nothing more than an immensely extended zone of stars, that is, of suns, since each star, from the most brilliant to the faintest, is a sun.
Here, then, is an immense group, a gigantic assemblage of worlds, which seems to embrace all the universe, if it be true that the greater number of the scattered stars situated out of the Milky Way nevertheless form part of it. In reality, this multitude of millions of suns is divided into numerous and distinct groups, and those into others still more restricted in number, each composed of two or three suns.