Notable Events Of The Nineteenth Century Part 8

It is difficult to apprehend the tremendous strides which we have made in the production of telescopes and the consequent increase in our sweep of the heavens. It was only in 1774 that the elder Herschel began his work in the construction of reflecting telescopes. These he gradually increased in size, until near the close of the century, when he produced an instrument which magnified two hundred and twenty-seven diameters. In the course of his career he built two hundred telescopes, having a seven-foot focus; 150 of ten feet and about eighty of twenty feet each.

With these instruments the astronomical work in the last quarter of the eighteenth century was mostly performed. The study of the heavens at this epoch began to reach out from the planetary system to the fixed stars. In this work Herschel led the way. The planet Ura.n.u.s at first bore the name of Herschel, from its discoverer. Sir John Herschel, son of Sir William, was born in 1792. All of his astronomical work was accomplished in our century. Following the line of his father, he used the reflecting telescope, and it was an instrument of this kind that he took to his observatory at the Cape of Good Hope. Lord Rosse was born in the year 1800. Under his auspices the reflecting telescope reached its maximum of power and usefulness.

His great reflector, built in his own grounds at Birr Castle, Ireland, was finished in 1844. This instrument was the marvel of that epoch. It had a focal distance of fifty-three feet, and an aperture of six feet.

With this great telescope its master reached out into the region of the nebulae, and began the real work of exploring the sidereal heavens.

In the reflecting telescope, however, there are necessary limitations.

Before the middle of this century, it was known that the future of astronomy depended upon the refracting lens, and not on the speculum.

The latter, in the hands of the two Herschels and Rosse, had reached its utmost limits--as is shown by the fact that to this day the Rosse telescope is the largest of its kind in the world.

Meanwhile the production of refracting telescopes made but slow progress. As late as 1836 the largest instrument of this kind in the world was the eleven-inch telescope of the observatory at Munich. The next in importance was a nine and a half-inch instrument at Dorpat, in Russia. This was the telescope through which the astronomer Struve made his earlier studies and discoveries. His field of observation was for the most part the fixed and double stars. At this time the largest instrument in the United States was the five-inch refractor of Yale College. Soon afterward, namely, in 1840, the observatory at Philadelphia was supplied with a six-inch refracting telescope from Munich.

German makers were now in the lead, and it was not long until a Munich instrument having a lens of eleven inches diameter was imported for the Mitch.e.l.l Observatory on Mount Adams, overlooking Cincinnati. About the same time a similar instrument of nine and a half inches aperture was imported for the National Observatory at Was.h.i.+ngton. To this period also belongs the construction of the Cambridge Observatory, with its fifteen-inch refracting telescope. Another of the same size was produced for the Royal Observatory at Pulkova, Russia. This was in 1839; and that instrument and the telescope at Cambridge were then the largest of their kind in the world.

The history of the telescope-making in America properly begins with Alvan Clark, Sr., of Cambridgeport, Ma.s.sachusetts. It was in 1846 that he produced his first telescope. Of this he made the lens, and such was the excellence of his work that he soon became famous, to the degree that the importation of foreign telescopes virtually ceased in the United States. Nor was it long until foreign orders began to arrive for the refracting lenses of Alvan Clark & Sons. The fame of this firm went out through all the world, and by the beginning of the last quarter of the century the Clark instruments were regarded as the finest ever produced.

We cannot here refer to more than a few of the princ.i.p.al products of Clark & Sons. Gradually they extended the width of their lenses, gaining with each increase of diameter a rapidly increasing power of penetration. At last they produced for the Royal Observatory of Pulkova a twenty-seven-inch objective, which was, down to the early eighties, the master work of its kind in the world. It was in the grinding and polis.h.i.+ng of their lenses that the Clarks surpa.s.sed all men. In the production of the gla.s.s castings for the lenses, the French have remained the masters. At the gla.s.s foundry of Mantois, of Paris, the finest and largest discs ever produced in the world are cast. But after the castings are made they are sent to America, to be made into those wonderful objectives which const.i.tute the glory of the apparatus upon which the New Astronomy relies for its achievements.

It was in the year 1887 that the Lick Observatory on Mount Hamilton, of the Coast Range in Southern California, was completed. The lens of this instrument is thirty-six inches in diameter. Nor will the reader without reflection readily realize the enormous stride which was made in telescopy when the makers advanced from the twenty-seven-inch to the thirty-six-inch objective. Lenses are to each other in their power of collecting light and penetrating apace as the squares of their diameters, and in the extent of s.p.a.ce explored as the cubes of their diameters.

The objective of the Pulkova instrument is to that of the Lick Observatory as 3 is to 4. The squares are as 9 is to 16, and the cubes are as 27 is to 64. This signifies that the depth of s.p.a.ce penetrated by the Lick instrument is to that of its predecessor as 16 is to 9, and that the astronomical sphere resolved by the former is to the sphere resolved by the latter as 64 is to 27--that is, the Lick instrument at one bound revealed a universe _more than twice as great_ as all that was known before! The human mind at this one bound found opportunity to explore and to know a sidereal sphere more than twice as extensive as had ever been previously penetrated by the gaze of man.

Nor is this all. The ambition of American astronomers and American philanthropists has not been content with even the prodigious achievement of the Lick telescope. In recent years an observatory has been projected in connection with the University of Chicago, which has come almost to completion, and which will bear by far the largest telescopic instrument in the world. The site selected for the observatory is seventy-five miles from the city, on the northern sh.o.r.e of Lake Geneva. There is a high ground here, rising sufficiently into a clear atmosphere, nearly two hundred feet above the level of the lake.

The observatory and the great telescope which const.i.tutes its central fact are to bear the name of the donor, Mr. Yerkes, of Chicago, who has contributed the means for rearing this magnificent adjunct of the University. The enterprise contemplated from the first the construction of the most powerful telescope ever known. The manufacture of the objective, upon which everything depends, was a.s.signed to Mr. Alvan G. Clark, of Cambridgeport, Ma.s.sachusetts, who is the only living representative of the old firm of Alvan Clark & Sons.

Alvan G. Clark has inherited much of the genius of his father, though it is said that in making the lens of the Lick Observatory the father had to be called from his retirement to superintend personally some of the more delicate parts of the finis.h.i.+ng before which task his sons had quailed. But the younger Clark readily agreed to make the Geneva lens, under the order of Yerkes, and to produce a perfect objective _forty inches in diameter_! This important work, so critical--almost impossible--has been successfully accomplished.

The making and the mounting of the Yerkes telescope have been a.s.signed to Warner & Swasey, of Cleveland, Ohio, who are recognized as the best telescope builders in America. The great observatory is approaching completion. The instrument itself has been finished, examined, accepted by a committee of experts, and declared to fulfill all of the conditions of the agreement between the founder and the makers. Thus, just north of the boundary line between Illinois and Wisconsin, the greatest telescope of the world has been lifted to its dome and pointed to the heavens.

The formal opening of the observatory is promised for the summer months of 1896. The human mind by this agency has made another stride into the depths of infinite s.p.a.ce. Another universe is presently to be penetrated and revealed. A hollow sphere of s.p.a.ce outside of the sphere already known is to be added to the already unthinkable universe which we inhabit. Every part of the immense observatory and of the telescope is of American production, with the single important exception of the cast gla.s.s disc from which the two princ.i.p.al lenses, the one double convex and the other plano-concave, are produced. These were cast by Mantois, of Paris, whose superiority to the American manufacturers of optical gla.s.s is recognized.

It is estimated that the Yerkes telescope will gather three times as much light as the twenty-three-inch instrument of the Princeton Observatory. It surpa.s.ses in the same respect the twenty-six-inch telescope at the National Observatory in the ratio of two and three-eighths to one. It is in the same particular one and four-fifth times as powerful as the instrument of the Royal Russian Observatory at Pulkova; and it surpa.s.ses the great Lick instrument by twenty-three per cent.

What the practical results of the study of the skies through this monster instrument will be none may predict. Theoretically it is capable of bringing the moon to an apparent distance of sixty miles.

Under favorable circ.u.mstances the observer will be able to note the characteristics of the lunar landscape with more distinctness than a good natural eye can discern the outlines and character of the summit of Pike's Peak from Denver. The instrument has sufficient power to reveal on the lunar disc any object five hundred feet square. Such a thing as a village or even a great single building would be plainly discernible.

Professor C.A. Young has recently pointed out the fact that the Yerkes telescope, if it meets expectation, will show on the moon's surface with much distinctness any such object as the Capitol at Was.h.i.+ngton.

It is complained that in America wealth is selfish and self-centred; that the millionaire cares only for himself and the increase of his already exorbitant estate. The ambition of such men as Lick of San Jose and Yerkes of Chicago, seems to ameliorate the severe judgment of mankind respecting the holders of the wealth of the world, and even to transform them from their popular character of enemies and misers into philanthropists and benefactors.

THE NEW ASTRONOMY.

This century has been conspicuous above all centuries for new things.

Man has grown into new relations with both nature and thought. He has interpreted nearly everything into new phraseology and new forms of belief. The scientific world has been revolutionized. Nothing remains in its old expression. Chemistry has been phrased anew. The laws of heat, light and electricity have been either revised or discovered wholly out of the unknown. The concept of universal nature has been so translated and reborn that a philosopher coming again out of the eighteenth century would fail to understand the thought and speech of even the common man.

In no other particular has the change been more marked than with respect to the general theory of the planetary and stellar worlds. A New Astronomy has come and taken the place of the old. The very rudiments of the science have to be learned as it were in a new language, and under the laws and theories of a new philosophy. Nature is considered from other points of view, and the general course of nature is conceived in a manner wholly different from the beliefs of the past.

In a preceding study we have explained the general notion of planetary formation according to the views of the last century. The New Astronomy presents another theory. Beginning with virtually the same notion of the original condition of our world and sun cl.u.s.ter, the new view departs widely as to the processes by which the planets were formed, and extends much further with respect to the first condition and ultimate destiny of our earth. The New Astronomy, like the old, begins with a nebular hypothesis. It imagines the matter now composing the solar group to have been originally dispersed through the s.p.a.ce occupied by our system, and to have been in a state of attenuation under the influence of high heat. Out of this condition of diffusion the solar system has been evolved. The idea is a creation by the process of evolution; it is evolution applied to the planets. More particularly, the hypothesis is that the worlds of our planetary system grew into their present state through a series of stages and slow developments extending over aeons of time.

This is the notion of world-growth subst.i.tuted for that of world-production en ma.s.se by the action of centrifugal force and discharge from the solar equator. The New Astronomy proposes in this respect two points of remarkable difference from the view formerly entertained. The first relates to the fixing of the planetary orbits, and the other to the process by which the planets have reached their present ma.s.s and character. The old theory would place a given world in its pathway around the sun by a spiral flinging off from the central body, and would allow that the aggregate ma.s.s of the globe so produced was fixed once for all at the beginning. The new theory supposes that a given planetary orbit, as for instance that of the earth, was marked in the nebula of our system before the system existed--that is, that our orbit had its place in the beginning just as it has now; that the orbit was not determined by solar revolution and centrifugal action, but that it was mathematically existent in the nebular sheet out of which the solar system was produced.

Other lines existed in the same sheet of matter. One of these lines or pathways was destined for the orbit of Mercury; another for the orbit of Venus. One was for the pathway of Mars; another for the belt of the asteroids; another for Jupiter; another for Saturn, and still two others, far off on the rim, for Ura.n.u.s and Neptune. The theory continues that such are the laws of matter that these orbital lines _must_ exist in a disc of fire mist such as that out of which our solar universe has been produced. The New Astronomy holds firmly to the notion that the orbits of the planets are as much a part of the system as the planets themselves, and that both orbit and planet exist in virtue of the deep-down mathematical formulae on which the whole material universe is constructed.

Secondly, the New Astronomy differs from the old by a whole horizon in the notion of world-production. About the middle of the century the theory began to be advanced that the worlds _grew_ by accretion of matter; that they grew in the very paths which they now occupy; that they began to be with a small aggregation of matter rus.h.i.+ng together in the line or orbit which the coming planet was to pursue. The planetary matter was already revolving in this...o...b..t and in the surrounding s.p.a.ces. It was already floating along in a nebulous superheated form capable of condensation by the loss of heat, but in particular capable of growth and development by the fall of surrounding matter upon the forming globe. We must remember that in the primordial state the elements of a planet, as for instance our earth, were mixed together and held in a state of tenuity ranging all the way from solid to highly vaporized forms, and that these elements subsequently and by slow adjustment got themselves into something approximating their present state.

The New Astronomy contemplates a period when each of the planets was a germinal nucleus of matter around which other matter was precipitated, thus producing a kind of world-growth or accretion. Thus, for instance, our earth may be considered at a time when its entire ma.s.s would not, according to our measurement, have weighed a hundred pounds! It consisted of a nucleus around which extended, through a great s.p.a.ce, a ma.s.s of attenuated planetary matter. The nucleus once formed the matter adjacent would precipitate itself by gravitation upon the surface of the incipient world. The precipitation would proceed as heat was given off into s.p.a.ce. It was virtually a process of condensation; but the result appeared like growth.

To the senses a planet would seem to be forming itself by accretion; and so, indeed, in one sense it was; for the ma.s.s constantly increased. As the nucleus sped on in the prescribed pathway, it drew to itself the surrounding matter, leaving behind it an open channel.

The orbit was thus cleared of the matter, which was at first merely nebular, and afterward both nebular and fragmentary. The growth at the first was rapid. With each revolution a larger band of s.p.a.ce was swept clear of its material. With each pa.s.sage of the forming globe the matter from the adjacent s.p.a.ces would rush down upon its surface, and as the ma.s.s of the planet increased the process would be stimulated; for gravitation is proportional to the ma.s.s. At length a great tubular s.p.a.ce would be formed, having the orbit of the earth for its centre, and in this s.p.a.ce the matter was all swept up. The tube enlarged with each revolution, until an open way was cut through the nebular disc, and then from the one side toward Venus and from the other side toward Mars the s.p.a.ce widened and widened, until the globe took approximately by growth its present ma.s.s of matter. The nebulous material was drawn out of the inter-planetary s.p.a.ce where it was floating, and the shower of star dust on the surface of the earth became thinner and less frequent. In some parts of the orbit bands or patches of this material existed, and the earth in pa.s.sing through such hands drew down upon itself the flying fragments of such matter as it continues to do to the present day. What are meteoric displays but the residue of the primordial showers by which the world was formed?

All this work, according to the New Astronomy, took place while our globe was still in a superheated condition. The ma.s.s of it had not yet settled into permanent form. The water had not yet become water; it was steam. The metals had not yet become metals; they were rather the vapor of metals. At length they were the liquids of metals, and at last the solids. So, also, the rocks were transformed from the vaporous through the liquid into the solid form--all this while the globe was in process of condensation. It grew smaller in mathematical measurements at the same time that it grew heavier by the accretion of matter. At last the surface was formed, and in time that surface was sufficiently cooled to allow the vapors around it to condense into seas and oceans and rivers. There were ages of superficial softness--vast epochs of mud--in which the living beings that had now appeared wallowed and sprawled.

We cannot trace the world-growth through all its stages but can only indicate them as it were in a sketch. The more important thing to be noted is the relation of our planet in process of formation to the great fact called life. Here the New Astronomy comes in again to indicate, theoretically at least, the philosophy of planetary evolution. Each planet seems to pa.s.s through a vast almost inconceivable period in which its condition renders life on its surface or in its structure impossible. Heat is at once the favoring and the prohibitory condition of life. Without heat life cannot exist; with too great heat life cannot exist. With an intermediate and moderate degree of heat many forms of animate and inanimate existence may be promoted.

These facts tend to show that every world has in its career an intermediate period which may be called the epoch of life. Before the epoch of life begins there is in the given world no such form of existence. There is matter only. Then at a certain stage the epoch of life begins. The epoch of life continues for a vast indeterminate period. No doubt in some of the worlds an epoch of life has been provided ten times as great, possibly a thousand times as great, as in other planets. After the epoch of life begins only certain forms of existence are for a while possible. Then other and higher forms succeed them, and then still higher. Thus the process continues until the highest--that is, the conscious and moral form of existence becomes possible, and that highest, that conscious, that moral form of being is ourselves.

This is not all. The epoch of life seems to be terminable at the further extreme by a planetary condition in which life is no longer possible. The New Astronomy indicates the coming of a condition in all the worlds when life must disappear therefrom and be succeeded by a lifeless state of worldhood. This may be called the epoch of death--that is, of world-death. It seems to be almost established by investigation and right reason that worlds die. They reach a stage in which they are lifeless. They cool down until the waters and gases that are on the surface and above the surface recede more and more into the surface and then into the interior, until they wholly disappear. Cold takes the throne of nature. Universal aridity supervenes, and all forms of vegetable and animate existence go away to return no more. They dwindle and expire. The conditions that have come are virtually conditions of death.

Whether the universe contains within itself, under the Almighty supervision, certain arrangements and laws by which the dead world can be again cast into the crucible and regenerated by liberation through the action of heat into its primordial state once more and go the same tremendous round of planet life, we know not. The conception of such a process, even the dream or vague possibility of it, is sufficiently sublime and fills the mind with a great delight in contemplating the possible cycles through which the material universe is pa.s.sing.

At any rate, we may contemplate the three great stages of world-life with which we are already acquainted--that is, the birth stage, the epoch of life and the epoch of death. There is a birth, as also a life and a death of planets. Richard A. Proctor, of great fame, on one of his last tours of instructive lecturing among our people, had for his subject the "Birth and Death of Worlds." The theme was not dissimilar to that which has been here presented in outline. The birth, the life and the death of worlds! Such is a summary of that almost infinite history through which our earth is pa.s.sing--the history which the globe is _making_ on its way from its nebulous to its final state.

Such, if we mistake not, is the story epitomized--the life history in brief--of all the worlds of s.p.a.ce. They have each in its order and kind, an epoch of the beginning, then an epoch of growth and evolution, then an epoch of life--toward which all the preceding planet history seems to tend--and finally an epoch of death which must, in the course of infinite time, swallow from sight each planet in its turn, or at least reduce each from that condition in which it is an arena of animated existence into that state where it is a frozen and desert clod, still following its wonted path through s.p.a.ce, still s.h.i.+ning with a cold but cheerful face, _like our moon_, upon the silent abysses of the universe.

WHAT THE WORLDS ARE MADE OF.

The present century was already well advanced before there was any solid ground for the belief that the worlds of s.p.a.ce are made of a.n.a.logous or identical materials. It was only with the invention of the spectroscope and the a.n.a.lysis of light that the material ident.i.ty of universal nature was proved by methods which could not be doubted.

The proof came by the spectroscope.

This little instrument, though not famed as is its lordly kinsman the telescope, or even regarded with the popular favor of the microscope, has nevertheless carried us as far, and, we were about to say, taught us as much, as either of the others. It is one thing to see the worlds afar, to note them visibly, to describe their outlines, to measure their ma.s.s and determine their motions. It is another thing to know their const.i.tution, the substances of which they are composed, the material condition in which they exist and the state of their progress in worldhood. The latter work is the task of the spectroscope; and right well has it accomplished its mission.

The solar spectrum has been known from the earliest ages. When the sun-bow was set on the background of cloud over the diluvial floods, the living beings of that age saw a spectrum--the glorious spectrum of rain and s.h.i.+ne. Wherever the rays of light have been diffracted under given conditions by the agency of water drops, prism of gla.s.s or other such transparent medium, and the ray has fallen on a suitable screen, lo! there has been the beautiful spectrum of light.

The artificial, intentional production of this phenomenon of light has long been known, and both novice and scientist have tested and improved the methods of getting given results. The child's soap-bubble shows it in miniature splendor. The pressure of one wet pane of gla.s.s against another reveals it. The breakage of nearly all crystalline substances brings something of the colored effects of light; but the triangular prism of gla.s.s, suitably prepared, best of all displays the a.n.a.lysis of the sun-beam into the colors of which it is composed.

The spectroscope is the improved instrument by which the diffracting prism is best employed in producing the spectrum. The reader no doubt has seen a spectroscope, and has observed its beautiful work. In this place we pa.s.s, however, from the instrument of production to the spectrum, or a.n.a.lyzed result, as the same is shown on a screen. There the pencil of white light falling from the sun is spread out in the manner of a fan, presenting on the screen the following arrangement of colors: red, orange, yellow, green, blue, indigo and violet.

This order of colors, beginning with red, starts from that side of the spectrum which is least bent from the right line in which the white ray was traveling. The violet rays are most bent. The red rays are thus said to be at the _lower_ edge of the prism, and the violet rays at the _upper_ edge. Below the red rays there are now known to be certain invisible rays, as of heat and electricity. Above the violet rays are other invisible rays, such as the actinic influence. In fact, the spectrum, beginning invisibly, pa.s.ses by way of the visible rays to the invisible again. Nor can any scientist in the world say at the present time _how much_ is really included in the spread-out fan of a.n.a.lyzed sunlight.

Thus much scientists have known for some time. Certain other facts, however, in connection with the solar spectrum are of greater importance than are its more sensible phenomena. It was in the year 1802 that the English physicist, William Hyde Wollaston, discovered that the solar spectrum is crossed with a large number of _dark lines_. He it was who first mapped these lines and showed their relative position. He it was also who discovered the existence of invisible rays above the violet. Twelve years afterward Joseph von Fraunhofer, of Munich, a German optician of remarkable talents, took up the examination of the Wollaston lines, and by his success in the investigation succeeded in attracting the attention of the world.

This second stage in scientific discovery is generally that which receives the plaudits of mankind. It was so in the case of Fraunhofer.

His name was given to the dark lines in the solar spectrum, and the nomenclature is retained to the present time. They are called the "Fraunhofer lines." It was soon discovered that the lines in question as produced in the spectrum are due to the presence of gases in the producing flame or source of light. It was also discovered that each substance in, the process of combustion yields its own line or set of lines. These appear at regular intervals in the spectrum. When several substances are consumed at the same time; the lines of each appear in the spectrum. The result is a _system_ of lines, becoming more and more complex as the number of elements in the consuming materials is increased.

The lines in a narrow spectrum fall so closely together that they cannot be critically examined; but when more than one prism is used and the spectrum by this means spread out widely, the dark lines are made to stand apart. They are then found to number many thousands. We speak now of the a.n.a.lysis of sunlight. Experimentation was naturally turned, however, to terrestrial gases and solids on fire, and it was found that these also produce like series of dark lines in the spectrum. Or when the substances are consumed _as solids_, then the spectral effects are reversed, and the lines that would be dark lines in the luminous colored spectrum become themselves luminous lines on the screen; but these lines hold the same relation in mathematical measurement, etc., as do the _dark_ lines in the colored spectrum.

Skillful spectroscopists succeeded in detecting and delineating the lines that were peculiar to each substance. By burning such substances in flame, they were able to produce the lines, and thus verify results. By such experimentation the various lines present in the solar spectrum were separated from the complex result, and the conclusion was reached that in the burning surface of the sun certain substances _well known on earth are present_; for the lines of those substances are shown in the spectrum.