there are large areas of subsidence and of elevation on the surface of the globe. But when we consider the slow rate at which that oscillation is now proceeding, and argue back from the known to the unknown, we are landed in conclusions as to the length of time required for geological changes which the opponents of the theory declare to be absolutely inadmissible.

Sir William Thomson, Professor Tait, and Mr. Croll argue the question as one of geological dynamics. They find reason, in recent discoveries of science, to assert that the sun and the earth, from their physical condition, cannot possibly have existed for the enormous length of time supposed. Playfair, the founder of what is called the Uniformitarian school of geology, declares on the other hand, that in the existing order of things there is no evidence either of a beginning or of an end. In the planetary motions,' he says, 'where geometry has carried the eye so far both into the future and the past, we discover no mark either of the commencement or the termination of the present order. The author of Nature has not given laws to the Universe, which, like the institutions of men, carry in themselves the elements of their own destruction.' This was a bold assertion: it was adopted with very little limitation by Sir Charles Lyell, and the later geologists--his disciples and contemporaries. Indeed, if they admitted any limitations at all, they placed the origin of the world so many hundreds of millions of years ago that the figures convey no practical idea to the mind, and amount in effect almost to what a distinguished geologist calls

'eternity à parte ante.'

The principal grounds upon which scientific opinion has recently declared itself in favor of limited periods for the duration of the solar system are based, first, on the belief that the earth is cooling-if not rapidly-at such a rate as to make it impossible that it should have existed for very many millions of years; secondly, because there is reason to believe that the earth is not now rotating on her axis with the same rapidity as in former ages, and that, as her shape would have been different if, at the time she was in a molten state, she had been rotating more rapidly than now, she has

not been rotating so long as has been supposed; thirdly, because the sun is parting with caloric at such a rate as to make it certain that he could not have continued to radiate heat at the same rate for more than a few millions of years; and lastly, because the changes in the earth's crust, stupendous and varied as they are, could have been, and probably were, accomplished in the course of much shorter periods than popular geology has hitherto considered possible.

It will, of course, be understood that any inquiry as to the date of creation must necessarily have relation only to the solar system-the sun, that is, and the planets which accompany the earth in its orbit round the central luminary.

The investigation is of necessity thus narrowed, because we have not, and cannot expect to have, any definite information as to the age of the rest of the visible universe. The stars are forever beyond our ken. If the spectroscope can bring intelligence of their component elements, it is as much as we can hope to attain. For their immeasurable distance effectually removes them from investigation. No action of gravity emanating from those distant luminaries affects the internal economy of the solar system. In the vast eternity of space the sun and his attendant satellites are altogether alone.

It is difficult to gaze upon the thousands of stars that brighten the night with their radiance and yet realise our entire isolation. The solar system, with the radius of its orbit stretching from the sun to farthest Neptune, is but a point in a vast solitude. No star is nearer to us than 200 millions of millions of miles.

This inconceivable remoteness shows that the sun and his satellites lie apart in space. They form one whole, interdependent on each other, but completely removed, as regards their internal economy, from the influence of any attraction outside.

There are reasons for concluding that the system, thus organised and isolated, was brought into existence by one continuous act of creative energy, and that, however long the period over which the process may have been spread, the whole solar system forms part of one

together from different parts of infinite space. We may then safely conclude that the solar system is absolutely isolated in space, and is collectively the result of one act of creation. To the solar system, therefore, our inquiry is exclusively confined.

Although the received chronology of the world has for ages rested upon the supposed authority of the Bible, the sacred text really says nothing at all upon the subject. But, though the assertions which were so long made upon its supposed authority are not really contained in the Pentateuch, it is curious to observe how exactly the words of Moses appear to fit the most recent discoveries of science. No one has supposed that we were intended to learn science from the Bible; it is, therefore, an unexpected advantage to find that its short but pregnant sentences directly support the interpretation put by modern research upon the hieroglyphics of nature. Moses teaches, just as modern science teaches, that the starry heavens existed far back in past duration, before the creation of the earth. He describes in majestic words the emptiness' of chaos, and the condition of affairs from which light arose. He describes the formation of the sun, and its gradual condensation into a lightholder' to give light upon the earth, in terms that almost seem to anticipate Herschel and Laplace. Far from assigning any date to the Creation, he is content to refer it to 'former duration.' No date is either mentioned or implied.

The so-called chronology was derived from two lists, one extending from Adam to Noah, the other from Noah to Abraham. These lists purport to give the direct line of descent from father to son, and the age of each individual member of the genealogy at the time when the next in succession was born. As Adam was supposed to have been created six days after the commencement of the Creation, it was simple work to add up the sum and fix the age of the world. As long as the progress of physical science showed no necessity for supposing a lengthened period to elapse between the creation of the world and the creation of man, it was taken for granted almost without discussion, that when God had created the heavens and the

earth in the beginning, He at once set about the work of arranging them for the use of man; that He distributed this work over six ordinary days, and at the close of the sixth day introduced our first parent on the scene.

Nowadays, all divines, English and foreign, agree that the word employed by Moses, and translated in our Bible by the beginning,' expresses duration or time previous to creation. Reshith, the Hebrew word for beginning, is in the original used without the definite article. The article was expressly omitted in order to exclude the application of the word to the order of creation, and to make it signify previous duration or previous eternity. The words of Moses then, 'In former duration God created the heavens and the earth,' may mean millions of years just as easily as one. A few verses later, describing the seconá day of creation, Moses declares that God made the firmament and called it heaven. It is plain from this that the heavens of the first day's creation are different from the heavens of the second day; the difference of time proves a difference of subject. The heavens of the first verse were made in former duration, before the moving of the Spirit, before the creation of light; the heavens of the second day were made after the earth and after light.

It is

Another statement made by Moses is an extraordinary anticipation of the most recent cosmological doctrines. 'The earth was desolation and emptiness and darkness upon the face of the raging deep, and the Spirit of God brooding upon the face of the waters.' now hardly doubtful that the earth was a molten sphere, over which hung, in a dense vapor, all the water which now lies upon its surface. As the crust cooled, the aqueous vapor that surrounded it became condensed into water and rested on the surface of the land. The conflicts between the waters and the fiery heat, as the crust of the earth was broken, fell in, or was upheaved, are well described by the words of Moses, the earth was desolation and emptiness. It is curious that the great facts of the submersion of the earth and its condition of emptiness should have been thus exactly described by Moses.

We are then told that God said, 'Let

.

there be light, and there was light.' Celsus, Voltaire, and a writer in Essays and Reviews' have found it strange that there should have been light before the creation of the sun; but according to the theory of cosmogony now almost universally received, the earth did in fact exist before the con

densation of the sun. Light there would be, from the gradually condensing mass cf nebulous and incandescent matter which occupied the whole space now circumscribed by the orbit of the earth. If Moses had wished to describe the modern doctrine concerning light, he could not have done so more happily. The sun is not called 'ór,' light, but Maór, a place of light, just what modern science has discovered it to be. If light be not matter, but vibrations of luminiferous ether, no words could more precisely explain what must have occurred when God set in motion the undulations which produced light, and said 'Let light be.' The account given of the creation of the sun very closely anticipated modern science: 'Let there be lightholders in the firmament of heaven, and let them be for lightholders in the firmament of heaven to give light upon the earth . . . and the stars.' When the sun began to give his light, then, for the first time, the earth's fellow-planets, the stars, began to reflect his brilliance, and became luminaries also.

'Vestiges of Creation' was one of the first books which fairly awakened public interest in the debatable land which lies between that which is certainly known to science and that which must always defy inquiry. Before the appearance of that remarkable book, the theory that the sun and its attendant planets were produced by the condensation of a vast nebula, was but little known to the unscientific world. The idea was originally entertained by Sir William Herschel, and affords one of the greatest proofs of his commanding genius. It was afterwards elaborated by Laplace; but that great astronomer was himself distrustful of it, and while he expounded the mechanical laws by which the proposed explanation could be supported, he was careful to speak of it only as an hypothesis. As time goes

on, it seems probable that the saying of Arago will be accepted, and that the views of Laplace will be universally acknowledged to be 'those only which, by their grandeur, their coherence, and their mathematical character, can be truly considered to form a physical cosmogony.'

But though Laplace is thus credited. by Arago with the origination of this grand conception, he was not its author. Sir William Herschel gave the earliest sketch of the theory. His views were expressed with so much precision, that one cannot help feeling a little jealousy for the prior right of discovery of the English astronomer. Herschel so plainly preceded Laplace, that it seems hard that Laplace should have the credit of it. Herschel began to search after the nebulæ in 1779, and soon formed a catalogue comprising an enormous number of them. By degrees it dawned upon his mind that the differences he observed in them were systematic, and at length occurred the magnificent intuition that the nebulæ are stars in the process of formation.

They lie in enormous numbers in every part of the heavens, and apparently in every stage of progressive development. The slow growth of worlds, extending over ages of time, cannot, of course, be watched by any single observer. No more can a single tree among the trees of a forest be so observed. But a forest contains specimens of saplings, young trees, trees of vigorous growth, and trees in decay. In like manner the heavens contain specimens of worlds in the making, from the chaotic mass of vapory matter which forms the first stage of cosmical existence to the perfect, self-luminous star. Herschel arranged them in classes showing this gradual development, and he declares that each class is so nearly allied to the next, that they do not differ so much as would the annual description of a human figure, if it were given from the birth of

a child till he comes to be a man in his prime. His catalogue arranges the objects he has actually observed somewhat in the following fashion: first, patches of extensively diffused nebulosity; 'milky nebulosity,' with condensation; round nebula; nebula, with a

nucleus; and so on till he reaches stellar nebulæ, nearly approaching the appearance of stars.

The evidence grows irresistible as we read, that in these wonderful objects we are gazing at works in process of formation as they lie plastic under the creative hand of the Almighty. Nor is it possible to withhold the inference-thus probably was the world we live in, and the solar system of which we form a part, evolved out of chaos.

The labors of Laplace commenced where Herschel ended. Herschel described what he saw. Laplace showed by mathematics how the known laws of gravitation could form, and probably did form, from such partially condensed mass of matter an entire planetary system.

It is supposed that a film of vaporous matter filled up the space which is now bounded by the orbit of the outermost planet of our system. To the eye of an observer, if such there were, in a distant star, such a vapor would appear like one of the numerous nebula which are everywhere visible in the heavens.

Laplace supposed that this nebula, extending beyond what is now the orbit of Neptune, possessed a rotary motion round its centre of gravity, and that the parts of it which were situated at the limits where the centrifgual force exactly counterbalanced the attractive force of the central nucleus, were abandoned by the central mass. Thus, as the nucleus became more and more dense under the action of gravity, were formed a succession of rings concentric with and revolving round the centre of gravity. Each ring would break up into masses which would be endued with motions of rotation, and would in consequence assume a spheroidal form. These masses formed the various planets, which in their turn condensing, cast off in some instances their outlying rings, as the central mass had done, and thus formed the moons or satellites which accompany the planets. As each planet was in turn cast off, the central mass contracted itself within the orbit of that last formed; till, after casting off Mercury, it gathered with immense energy round its own centre and formed the sun.

Laplace's mechanical explanation does not rest only on theory. It has been

experimentally shown that matter under certain conditions would exhibit phenomena similar in many important particulars to those which Laplace was led by mathematical considerations to suppose. Professor Plateau several years ago tried the experiment of pouring olive oil into alcohol and water, mixed in such proportions as exactly to equal the density of the oil. The oil thus became a liquid mass relieved from the operation of gravity, and free to take any exterior form which might be imposed by such forces as might be brought to bear upon it. The oil instantly took the form of a globe by virtue of molecular attraction. Professor Plateau then introduced a wire into the globe of oil in such a manner as to form for it a vertical axis. The wire had on it a little disc coincident with the centre of the globular mass, and by turning the axis the oil was made to revolve. The sphere soon flattened at the poles and bulged out at the equator, thus producing on a small scale an effect which is admitted to have taken place in the planets. The experiment has since been several times repeated. When the rotation becomes very rapid, the figure becomes more oblately spheroidal, then hollows out above and below round the axis of rotation, stretches out horizontally until finally the outside layer of oil abandons the mass and becomes transformed into a perfectly regular ring. After a little while the ring of oil losing its own motion gathers itself once more into a sphere. As often as the experiment is repeated the ring thrown off immediately takes the globular form. These are seen to assume at the instant of their formation a movement of rotation upon themselves, which takes place in the same direction as that of the ring. Moreover, as the ring at the instant of its rupture had still a remainder of velocity, the spheres to which it has given birth tend to fly off at a tangent; but as on the other side, the disc, turning in the alcoholic liquor, has impressed on the liquor a movement of rotation, the spheres are carried along and revolve for some time round the disc. Those which revolve at the same time upon themselves 'present the curious spectacle of planets revolving at the same time on themselves and in their orbit.' Another curious result is almost always