The Uses of Astronomy Part 4

THE COPERNICAN SYSTEM.

It is supposed that in the very dawn of science, Pythagoras or his disciples explained the apparent motion of the heavenly bodies about the earth by the diurnal revolution of the earth on its axis. But this theory, though bearing so deeply impressed upon it the great seal of truth, _simplicity_, was in such glaring contrast with the evidence of the senses, that it failed of acceptance in antiquity or the middle ages. It found no favor with minds like those of Aristotle, Archimedes, Hipparchus, Ptolemy, or any of the acute and learned Arabian or mediaeval astronomers. All their ingenuity and all their mathematical skill were exhausted in the development of a wonderfully complicated and ingenious, but erroneous history. The great master truth, rejected for its simplicity, lay disregarded at their feet.

At the second dawn of science, the great fact again beamed into the mind of Copernicus. Now, at least, in that glorious age which witnessed the invention of printing, the great mechanical engine of intellectual progress, and the discovery of America, we may expect that this long-hidden revelation, a second time proclaimed, will command the a.s.sent of mankind. But the sensible phenomena were still too strong for the theory; the glorious delusion of the rising and the setting sun could not be overcome. Tycho de Brahe furnished his Observatory with instruments superior in number and quality to all that had been collected before; but the great instrument of discovery, which, by augmenting the optic power of the eye, enables it to penetrate beyond the apparent phenomena, and to discern the true const.i.tution of the heavenly bodies, was wanting at Uranienburg. The observations of Tycho as discussed by Kepler, conducted that most fervid, powerful, and sagacious mind to the discovery of some of the most important laws of the celestial motions; but it was not till Galileo, at Florence, had pointed his telescope to the sky, that the Copernican system could be said to be firmly established in the scientific world.

THE HOME OF GALILEO.

On this great name, my Friends, a.s.sembled as we are to dedicate a temple to instrumental Astronomy, we may well pause for a moment.

There is much, in every way, in the city of Florence to excite the curiosity, to kindle the imagination, and to gratify the taste.

Sheltered on the north by the vine-clad hills of Fiesoli, whose cyclopean walls carry back the antiquary to ages before the Roman, before the Etruscan power, the flowery city (Fiorenza) covers the sunny banks of the Arno with its stately palaces. Dark and frowning piles of mediaeval structure; a majestic dome, the prototype of St. Peter's; basilicas which enshrine the ashes of some of the mightiest of the dead; the stone where Dante stood to gaze on the Campanile; the house of Michael Angelo, still occupied by a descendant of his lineage and name, his hammer, his chisel, his dividers, his ma.n.u.script poems, all as if he had left them but yesterday; airy bridges, which seem not so much to rest on the earth as to hover over the waters they span; the loveliest creations of ancient art, rescued from the grave of ages again to enchant the world; the breathing marbles of Michael Angelo, the glowing canvas of Raphael and t.i.tian, museums filled with medals and coins of every age from Cyrus the younger, and gems and amulets and vases from the sepulchers of Egyptian Pharaohs coeval with Joseph, and Etruscan Luc.u.mons that swayed Italy before the Romans,--libraries stored with the choicest texts of ancient literature,--gardens of rose and orange, and pomegranate, and myrtle,--the very air you breathe languid with music and perfume;--such is Florence. But among all its fascinations, addressed to the sense, the memory, and the heart, there was none to which I more frequently gave a meditative hour during a year's residence, than to the spot where Galileo Galilei sleeps beneath the marble door of Santa Croce; no building on which I gazed with greater reverence, than I did upon the modest mansion at Arcetri, villa at once and prison, in which that venerable sage, by command of the Inquisition, pa.s.sed the sad closing years of his life. The beloved daughter on whom he had depended to smooth his pa.s.sage to the grave, laid there before him; the eyes with which he had discovered worlds before unknown, quenched in blindness:

Ahime! quegli occhi si son fatti oscuri, Che vider piu di tutti i tempi antichi, E luce fur dei secoli futuri.

That was the house, "where," says Milton (another of those of whom the world was not worthy), "I found and visited the famous Galileo, grown old--a prisoner to the Inquisition, for thinking on astronomy otherwise than as the Dominican and Franciscan licensers thought."[A] Great Heavens! what a tribunal, what a culprit, what a crime! Let us thank G.o.d, my Friends, that we live in the nineteenth century. Of all the wonders of ancient and modern art, statues and paintings, and jewels and ma.n.u.scripts,--the admiration and the delight of ages,--there was nothing which I beheld with more affectionate awe than that poor, rough tube, a few feet in length,--the work of his own hands,--that very "optic gla.s.s," through which the "Tuscan Artist" viewed the moon,

"At evening, from the top of Fesole, Or in Valdarno, to descry new lands, Rivers, or mountains, in her spotty globe."

that poor little spy-gla.s.s (for it is scarcely more) through which the human eye first distinctly beheld the surface of the moon--first discovered the phases of Venus, the satellites of Jupiter, and the seeming handles of Saturn--first penetrated the dusky depths of the heavens--first pierced the clouds of visual error, which, from the creation of the world, involved the system of the Universe.

[Footnote A: Prose Works, vol. 1, p. 213.]

There are occasions in life in which a great mind lives years of rapt enjoyment in a moment. I can fancy the emotions of Galileo, when, first raising the newly-constructed telescope to the heavens, he saw fulfilled the grand prophecy of Copernicus, and beheld the planet Venus crescent like the moon. It was such another moment as that when the immortal printers of Mentz and Strasburg received the first copy of the Bible into their hands, the work of their divine art; like that when Columbus, through the gray dawn of the 12th of October, 1492 (Copernicus, at the age of eighteen, was then a student at Cracow), beheld the sh.o.r.es of San Salvador; like that when the law of gravitation first revealed itself to the intellect of Newton; like that when Franklin saw by the stiffening fibers of the hempen cord of his kite, that he held the lightning in his grasp; like that when Leverrier received back from Berlin the tidings that the predicted planet was found.

Yes, n.o.ble Galileo, thou art right, _E pur si muove._ "It does move."

Bigots may make thee recant it; but it moves, nevertheless. Yes, the earth moves, and the planets move, and the mighty waters move, and the great sweeping tides of air move, and the empires of men move, and the world of thought moves, ever onward and upward to higher facts and bolder theories. The Inquisition may seal thy lips, but they can no more stop the progress of the great truth propounded by Copernicus, and demonstrated by thee, than they can stop the revolving earth.

Close now, venerable sage, that sightless, tearful eye; it has seen what man never before saw--it has seen enough. Hang up that poor little spy-gla.s.s--it has done its work. Not Hersch.e.l.l nor Rosse have, comparatively, done more. Franciscans and Dominicans deride thy discoveries now; but the time will come when, from two hundred observatories in Europe and America, the glorious artillery of science shall nightly a.s.sault the skies, but they shall gain no conquests in those glittering fields before which thine shall be forgotten. Rest in peace, great Columbus of the heavens--like him scorned, persecuted, broken-hearted!--in other ages, in distant hemispheres, when the votaries of science, with solemn acts of consecration, shall dedicate their stately edifices to the cause of knowledge and truth, thy name shall be mentioned with honor.

NEW PERIODS IN ASTRONOMICAL SCIENCE.

It is not my intention, in dwelling with such emphasis upon the invention of the telescope, to ascribe undue importance, in promoting the advancement of science, to the increase of instrumental power.

Too much, indeed, cannot be said of the service rendered by its first application in confirming and bringing into general repute the Copernican system; but for a considerable time, little more was effected by the wondrous instrument than the gratification of curiosity and taste, by the inspection of the planetary phases, and the addition of the rings and satellites of Saturn to the solar family. Newton, prematurely despairing of any further improvement in the refracting telescope, applied the principle of reflection; and the nicer observations now made, no doubt, hastened the maturity of his great discovery of the law of gravitation; but that discovery was the work of his transcendent genius and consummate skill.

With Bradley, in 1741, a new period commenced in instrumental astronomy, not so much of discovery as of measurement. The superior accuracy and minuteness with which the motions and distances of the heavenly bodies were now observed, resulted in the acc.u.mulation of a ma.s.s of new materials, both for tabular comparison and theoretical speculation.

These materials formed the enlarged basis of astronomical science between Newton and Sir William Hersch.e.l.l. His gigantic reflectors introduced the astronomer to regions of s.p.a.ce before unvisited--extended beyond all previous conception the range of the observed phenomena, and with it proportionably enlarged the range of constructive theory. The discovery of a new primary planet and its attendant satellites was but the first step of his progress into the labyrinth of the heavens.

Cotemporaneously with his observations, the French astronomers, and especially La Place, with a geometrical skill scarcely, if at all, inferior to that of its great author, resumed the whole system of Newton, and brought every phenomenon observed since his time within his laws. Difficulties of fact, with which he struggled in vain, gave way to more accurate observations; and problems that defied the power of his a.n.a.lysis, yielded to the modern improvements of the calculus.

HERSCh.e.l.l'S NEBULAR THEORY.

But there is no _Ultima Thule_ in the progress of science. With the recent augmentations of telescopic power, the details of the nebular theory, proposed by Sir W. Hersch.e.l.l with such courage and ingenuity, have been drawn in question. Many--most--of those milky patches in which he beheld what he regarded as cosmical matter, as yet in an unformed state,--the rudimental material of worlds not yet condensed,--have been resolved into stars, as bright and distinct as any in the firmament.

I well recall the glow of satisfaction with which, on the 22d of September, 1847, being then connected with the University at Cambridge, I received a letter from the venerable director of the Observatory there, beginning with these memorable words:--"You will rejoice with me that the great nebula in Orion has yielded to the powers of our incomparable telescope! * * * It should be borne in mind that this nebula, and that of Andromeda [which has been also resolved at Cambridge], are the last strongholds of the nebular theory."[A]

[Footnote A: _Annals of the Observatory of Harvard College_, p. 121.]

But if some of the adventurous speculations built by Sir William Hersch.e.l.l on the bewildering revelations of his telescope have been since questioned, the vast progress which has been made in sidereal astronomy, to which, as I understand, the Dudley Observatory will be particularly devoted, the discovery of the parallax of the fixed stars, the investigation of the interior relations of binary and triple systems of stars, the theories for the explanation of the extraordinary, not to say fantastic, shapes discerned in some of the nebulous systems--whirls and spirals radiating through s.p.a.ces as vast as the orbit of Neptune;[A]

the glimpses at systems beyond that to which our sun belongs;--these are all splendid results, which may fairly be attributed to the school of Hersch.e.l.l, and will for ever insure no secondary place to that name in the annals of science.

[Footnote A: See the remarkable memoir of Professor Alexander, "On the origin of the forms and the present condition of some of the cl.u.s.ters of stars, and several of the nebulae," (Gould's _Astronomical Journal_, Vol.

iii, p. 95.)]

RELATIONs.h.i.+P OF THE LIBERAL ARTS.

In the remarks which I have hitherto made, I have had mainly in view the direct connection of astronomical science with the uses of life and the service of man. But a generous philosophy contemplates the subject in higher relations. It is a remark as old, at least, as Plato, and is repeated from him more than once by Cicero, that all the liberal arts have a common bond and relations.h.i.+p.[A] The different sciences contemplate as their immediate object the different departments of animate and inanimate nature; but this great system itself is but one, and its parts are so interwoven with each other, that the most extraordinary relations and unexpected a.n.a.logies are constantly presenting themselves; and arts and sciences seemingly the least connected, render to each other the most effective a.s.sistance.

[Footnote A: Archias, i.; De Oratore, iii., 21.]

The history of electricity, galvanism, and magnetism, furnishes the most striking ill.u.s.tration of this remark. Commencing with the meteorological phenomena of our own atmosphere, and terminating with the observation of the remotest heavens, it may well be adduced, on an occasion like the present. Franklin demonstrated the ident.i.ty of lightning and the electric fluid. This discovery gave a great impulse to electrical research, with little else in view but the means of protection from the thunder-cloud. A purely accidental circ.u.mstance led the physician Galvani, at Bologna, to trace the mysterious element, under conditions entirely novel, both of development and application. In this new form it became, in the hands of Davy, the instrument of the most extraordinary chemical operations; and earths and alkalis, touched by the creative wire, started up into metals that float on water, and kindle in the air. At a later period, the closest affinities are observed between electricity and magnetism, on the one hand; while, on the other, the relations of polarity are detected between acids and alkalis. Plating and gilding henceforth become electrical processes. In the last applications of the same subtle medium, it has become the messenger of intelligence across the land and beneath the sea; and is now employed by the astronomer to ascertain the difference of longitudes, to transfer the beats of the clock from one station to another, and to record the moment of his observations with automatic accuracy. How large a share has been borne by America in these magnificent discoveries and applications, among the most brilliant achievements of modern science, will sufficiently appear from the repet.i.tion of the names of Franklin, Henry, Morse, Walker, Mitch.e.l.l, Lock, and Bond.

VERSATILITY OF GENIUS.

It has sometimes happened, whether from the harmonious relations to each other of every department of science, or from rare felicity of individual genius, that the most extraordinary intellectual versatility has been manifested by the same person. Although Newton's transcendent talent did not blaze out in childhood, yet as a boy he discovered great apt.i.tude for mechanical contrivance. His water-clock, self-moving vehicle, and mill, were the wonder of the village; the latter propelled by a living mouse. Sir David Brewster represents the accounts as differing, whether the mouse was made to advance "by a string attached to its tail," or by "its unavailing attempts to reach a portion of corn placed above the wheel." It seems more reasonable to conclude that the youthful discoverer of the law of gravitation intended by the combination of these opposite attractions to produce a balanced movement. It is consoling to the average mediocrity of the race to perceive in these sportive a.s.says, that the mind of Newton pa.s.sed through the stage of boyhood. But emerging from boyhood, what a bound it made, as from earth to heaven! Hardly commencing bachelor of arts, at the age of twenty-four, he untwisted the golden and silver threads of the solar spectrum, simultaneously or soon after conceived the method of fluxions, and arrived at the elemental idea of universal gravity before he had pa.s.sed to his master's degree. Master of Arts indeed! That degree, if no other, was well bestowed. Universities are unjustly accused of fixing science in stereotype. That diploma is enough of itself to redeem the honors of academical parchment from centuries of learned dullness and scholastic dogmatism.

But the great object of all knowledge is to enlarge and purify the soul, to fill the mind with n.o.ble contemplations, to furnish a refined pleasure, and to lead our feeble reason from the works of nature up to its great Author and Sustainer. Considering this as the ultimate end of science, no branch of it can surely claim precedence of Astronomy. No other science furnishes such a palpable embodiment of the abstractions which lie at the foundation of our intellectual system; the great ideas of time, and s.p.a.ce, and extension, and magnitude, and number, and motion, and power. How grand the conception of the ages on ages required for several of the secular equations of the solar system; of distances from which the light of a fixed star would not reach us in twenty millions of years, of magnitudes compared with which the earth is but a foot-ball; of starry hosts--suns like our own--numberless as the sands on the sh.o.r.e; of worlds and systems shooting through the infinite s.p.a.ces, with a velocity compared with which the cannon-ball is a way-worn, heavy-paced traveler![A]

[Footnote A: Nichol's _Architecture of the Heavens_, p. 160.]

THE SPECTACLE OF THE HEAVENS.

Much, however, as we are indebted to our observatories for elevating our conceptions of the heavenly bodies, they present, even to the unaided sight, scenes of glory which words are too feeble to describe. I had occasion, a few weeks since, to take the early train from Providence to Boston; and for this purpose rose at 2 o'clock in the morning. Every thing around was wrapped in darkness and hushed in silence, broken only by what seemed at that hour the unearthly clank and rush of the train.

It was a mild, serene midsummer's night; the sky was without a cloud--the winds were whist. The moon, then in the last quarter, had just risen, and the stars shone with a spectral l.u.s.ter but little affected by her presence; Jupiter, two hours high, was the herald of the day; the Pleiades, just above the horizon, shed their sweet influence in the east; Lyra sparkled near the zenith; Andromeda veiled her newly discovered glories from the naked eye in the south; the steady Pointers, far beneath the pole, looked meekly up from the depths of the north to their sovereign.

Such was the glorious spectacle as I entered the train. As we proceeded, the timid approach of twilight became more perceptible; the intense blue of the sky began to soften, the smaller stars, like little children, went first to rest; the sister-beams of the Pleiades soon melted together; but the bright constellations of the west and north remained unchanged. Steadily the wondrous transfiguration went on. Hands of angels hidden from mortal eyes s.h.i.+fted the scenery of the heavens; the glories of night dissolved into the glories of the dawn. The blue sky now turned more softly gray; the great watch-stars shut up their holy eyes; the east began to kindle. Faint streaks of purple soon blushed along the sky; the whole celestial concave was filled with the inflowing tides of the morning light, which came pouring down from above in one great ocean of radiance; till at length, as we reached the Blue Hills, a flash of purple fire blazed out from above the horizon, and turned the dewy teardrops of flower and leaf into rubies and diamonds. In a few seconds the everlasting gates of the morning were thrown wide open, and the lord of day, arrayed in glories too severe for the gaze of man, began his course.

I do not wonder at the superst.i.tion of the ancient Magians, who in the morning of the world went up to the hill-tops of Central Asia, and ignorant of the true G.o.d, adored the most glorious work of his hand.

But I am filled with amazement, when I am told that in this enlightened age, and in the heart of the Christian world, there are persons who can witness this daily manifestation of the power and wisdom of the Creator, and yet say in their hearts, "There is no G.o.d."

UNDISCOVERED BODIES.

Numerous as are the heavenly bodies visible to the naked eye, and glorious as are their manifestations, it is probable that in our own system there are great numbers as yet undiscovered. Just two hundred years ago this year, Huyghens announced the discovery of one satellite of Saturn, and expressed the opinion that the six planets and six satellites then known, and making up the perfect number of _twelve_, composed the whole of our planetary system. In 1729 an astronomical writer expressed the opinion that there might be other bodies in our system, but that the limit of telescopic power had been reached, and no further discoveries were likely to be made.[A] The orbit of one comet only had been definitively calculated. Since that time the power of the telescope has been indefinitely increased; two primary planets of the first cla.s.s, ten satellites, and forty-three small planets revolving between Mars and Jupiter, have been discovered, the orbits of six or seven hundred comets, some of brief period, have been ascertained;--and it has been computed, that hundreds of thousands of these mysterious bodies wander through our system. There is no reason to think that all the primary planets, which revolve about the sun, have been discovered.

An indefinite increase in the number of asteroids may be antic.i.p.ated; while outside of Neptune, between our sun and the nearest fixed star, supposing the attraction of the sun to prevail through half the distance, there is room for ten more primary planets succeeding each other at distances increasing in a geometrical ratio. The first of these will, unquestionably, be discovered as soon as the perturbations of Neptune shall have been accurately observed; and with maps of the heavens, on which the smallest telescopic stars are laid down, it may be discovered much sooner.

[Footnote A: _Memoirs of A.A.S._, vol. iii, 275.]

THE VASTNESS OF CREATION.

But it is when we turn our observation and our thoughts from our own system, to the systems which lie beyond it in the heavenly s.p.a.ces, that we approach a more adequate conception of the vastness of creation. All a.n.a.logy teaches us that the sun which gives light to us is but one of those countless stellar fires which deck the firmament, and that every glittering star in that s.h.i.+ning host is the center of a system as vast and as full of subordinate luminaries as our own. Of these suns--centers of planetary systems--thousands are visible to the naked eye, millions are discovered by the telescope. Sir John Hersch.e.l.l, in the account of his operations at the Cape of Good Hope (p. 381) calculates that about five and a half millions of stars are visible enough to be _distinctly counted_ in a twenty-foot reflector, in both hemispheres. He adds, that "the actual number is much greater, there can be little doubt." His ill.u.s.trious father, estimated on one occasion that 125,000 stars pa.s.sed through the field of his forty foot reflector in a quarter of an hour.

This would give 12,000,000 for the entire circuit of the heavens, in a single telescopic zone; and this estimate was made under the a.s.sumption that the nebulae were ma.s.ses of luminous matter not yet condensed into suns.

These stupendous calculations, however, form but the first column of the inventory of the universe. Faint white specks are visible, even to the naked eye of a practiced observer in different parts of the heavens.

Under high magnifying powers, several thousands of such spots are visible,--no longer however, faint, white specks, but many of them resolved by powerful telescopes into vast aggregations of stars, each of which may, with propriety, be compared with the milky way. Many of these nebulae, however, resisted the power of Sir Wm. Hersch.e.l.l's great reflector, and were, accordingly, still regarded by him as ma.s.ses of unformed matter, not yet condensed into suns. This, till a few years since, was, perhaps, the prevailing opinion; and the nebular theory filled a large s.p.a.ce in modern astronomical science. But with the increase of instrumental power, especially under the mighty grasp of Lord Rosse's gigantic reflector, and the great refractors at Pulkova and Cambridge, the most irresolvable of these nebulae have given way; and the better opinion now is, that every one of them is a galaxy, like our own milky way, composed of millions of suns. In other words, we are brought to the bewildering conclusion that thousands of these misty specks, the greater part of them too faint to be seen with the naked eye, are, not each a universe like our solar system, but each a "swarm" of universes of unappreciable magnitude.[A] The mind sinks, overpowered by the contemplation. We repeat the words, but they no longer convey distinct ideas to the understanding.