Section 5. the Second Day.

"And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters.

"And God made the firmament, and divided the waters which were under the firmament from the waters which were above the firmament, and it was so.

"And God called the firmament Heaven, and there was evening and there was morning, a second day"

The work of the second and third days evidently has its scene on the earth alone. At its commencement the earth appears to have become distinctly separated from the gradually condensing mass of the solar system, and to have assumed its spherical form. It had, in fact, acquired an independent existence; but it was still in a chaotic state. Its elements, which were hereafter to assume the three forms of solid, fluid, and gas, seem to have been still blended together. Of the three states, fluidity seems to have been that to which the mass most nearly approached. This seems to be indicated by the application of the term, waters, to the two parts into which it is now divided; for the Hebrew has no general word for "fluid," so that the only method of expressing it was by the use of this word "water" in an extended signification; and all scientific investigations point to the same conclusion. The heat, as yet, must have been so intense that no rocks or metals with which we are acquainted could have remained in a solid form. The sorting out and first arrangement of the materials of the earth, with probably the farther development of a large portion of them by the introduction of a new element, seems to have been the work of the second day.

When we proceed to examine the narrative more closely, two important questions suggest themselves:--l. What special interference of Creative Power does it indicate? 2. What is the meaning of the division between the waters which were above the firmament and the waters which were under the firmament?

1. What special interference of Creative Power took place on the second day? Till within the last ten years, it would have been difficult to give a satisfactory answer to this question; for if all the elements were already in existence at the commencement of the second day, their arrangement would, as it seems, have been brought about by the ordinary operation of natural laws which were already established. The cooling and condensation of a portion of the elements would have been effected by the radiation of their heat, and the portions thus condensed would, under the influence of gravitation, have arranged themselves in immediate proximity to the centre of gravity, forming a solid or fluid nucleus, round which those portions which still remained in a gaseous state would have formed an atmospheric envelope. But here again the spectroscope comes to our aid. In many of the nebulae which give in it the bright lines indicative of gas, hydrogen and nitrogen are the chief gases discovered. These must be in an incandescent state, or they would not be visible at all. But hydrogen cannot, in the present state of things, remain in this condition in contact with oxygen; it must instantly combine with it, that combination being attended with intense heat, and resulting in the production of water. The introduction of oxygen, then, must involve a very important crisis in the process of development; but that introduction must have preceded the formation of atmospheric air and water. Prior to the second day oxygen must either have been non-existent, or it must have existed in a form and under conditions very different from those under which it exists now. Free oxygen cannot be in existence in the sun or in any celestial object in which the spectroscope indicates the existence of incandescent hydrogen. The special act of the second day would appear to have consisted in the development of oxygen, or the calling it from a quiescent state into active operation.

But the effects of the new element thus called into operation would not be limited to the production of air and water. It is estimated that oxygen constitutes, by weight, nearly half of the solid crust of the earth. It forms a part of every rock and of every metallic ore. The second day, then, must have been a period of intense chemical action, resulting from the introduction of this powerful agent.

But (2) what is the meaning of the division of the waters which are above the firmament from the waters which were under the firmament? At present all the water contained in the atmosphere, in the shape of vapour and clouds, is so insignificant in comparison with that vast volume of water which not only fills the ocean, but also permeates the solid earth, that such a notice of it seems unaccountable. Mr. Goodwin, indeed, maintains that there was an ancient belief, not only that the firmament was a solid vault, but that on it there rested another ocean, at least as copious as that with which we are acquainted. [Footnote: Essays and Reviews, p. 220] In support of this assertion he brings forward the phrase, "The windows of heaven were opened" (Gen, VII. 11) and other similar expressions. But such phrases as this evidently belong to the same class as the fanciful names so often given to the clouds in the hymns of the Rig Veda. Both expressions evidently point to a time when figurative language, if no longer a necessity, was at all events a common and favourite form of speech, and was understood by all. Dr. Whewell [Footnote: Plurality of Worlds, chap. x. Section 5.] has put forward the curious notion that when the creation of the interior planets was completed, there remained a superfluity of water, which was gathered up into the four exterior planets. But the only fact in favour of such an hypothesis is the close correspondence between the apparent density of these planets and that of water. Now, as will be seen immediately, there is strong reason to believe that the true density of these planets is much greater than their apparent diameters would seem to indicate; so that the one solitary ground on which the suggestion rests vanishes when it is examined. Apart from this, however, the suggestion that there would be any superfluous material when the work of creation was finished, is a very strange one. Neither of these views, then, can be accepted as giving a satisfactory meaning to the text.

Astronomical investigations however, which have been carried on with great diligence during the last four winters, and which are still being continued with unremitting interest, have brought to light phenomena which seem to be in remarkable correspondence with the state of things spoken of in the text. It has already been noticed that the eight greater planets at present known to us are divided into two groups of four by the intervening belt of minor planets. These two groups have totally distinct characteristics. In density, magnitude, and length, of day the members of each group differ little from each other, while the two groups differ very widely. The moon is the only satellite as yet known in the inner group. The planets of the outer group are attended by at least seventeen satellites.

Of these outer planets Jupiter, from his great brilliancy, specially attracts observation, while from his comparative proximity to the earth we are enabled to examine him much more satisfactorily than we can Saturn, Uranus, or Neptune. Two facts with reference to him have long been well known, the one, that the polar compression in his case is much greater than it is in any of the interior planets, so that when seen through a telescope of very moderate power his disc is evidently elliptical, while the compression of the interior planets can only be detected by the most delicate micrometrical measurements--the other, that his apparent surface is always crossed by several alternating belts of light and shade, which though subject to constant changes of detail, always preserve the same general character. Until recently the generally received theory was that these belts consisted of clouds, raised by the heat of the sun, and arranged in zones under the influence of winds similar in character to, and produced by the same causes as, the trade-winds which blow over our own oceans. This view, however, has been shown by Mr. Proctor to be untenable. [Footnote: See a paper by Mr. Proctor in the Monthly Packet for October, 1870.]

About forty years ago, a very remarkable phenomenon was observed simultaneously, but independently, by three astronomers, Admiral Smyth, Mr. Maclean, and Mr. Pearson, who were watching a transit of Jupiter's second satellite from stations several miles apart. Admiral Smyth's account of it is as follows:--"On Thursday, the 26th of June, 1828, the moon being nearly full, and the evening extremely fine, I was watching the second satellite of Jupiter as it gradually approached to transit the disc of the planet. My instrument was an excellent refractor of 3 3/4 inches aperture, and five feet focal length, with a power of one hundred. The satellite appeared in contact at about half-past ten, and for some minutes remained on the edge of the limb, presenting an appearance not unlike that of the lunar mountains which come into view during the first quarter of the moon, until it finally disappeared on the body of the planet. At least twelve or thirteen minutes must have elapsed when, accidentally turning to Jupiter again, I perceived the same satellite outside the disc. It was in the same position as to being above a line with the lower belt, where it remained distinctly visible for at least four minutes, and then suddenly vanished." A somewhat similar phenomenon, but of shorter duration, was witnessed by Messrs. Gorton and Wray, during an occultation of the same satellite, April 26, 1863. In this case the satellite reappeared after passing behind the apparent disc of the planet. So lately as 1868 this phenomenon was regarded as inexplicable. [Footnote: Webb's Celestial Objects, p. 141.]

In the winter of 1868-9 the attention of astronomers was called to the fact that rapid and extensive changes were taking place in the appearance of Jupiter's belts, and they have consequently been watched from that time with unremitting attention by astronomers furnished with telescopes of the best quality. The results of these observations are given in two very interesting papers, communicated to the Popular Science Review, by Mr. Webb. [Footnote: Popular Science Review for April, 1870, and July, 1871.] Very curious markings and variations in the depth of shade have been seen, accompanied by equally curious changes of colour. Mr. Browning compares these changes to those which are seen when a cloud of steam of varying depth and density is illuminated from behind by a strong light, as when we look through the steam escaping from the safety-valve of a locomotive at a gas-lamp immediately behind it. This appears to be the true explanation of the phenomenon. [Footnote: Popular Science Review, 1871, p. 307.] These belts are probably due to vast masses of steam, poured forth with great force from the body of the planet. As the atmosphere of Jupiter is probably of enormous depth, the rotatory velocity of its upper portions would be much greater than that of the surface of the planet, hence the steam would arrange itself in belts parallel to the equator of the planet. But this view leads us to wonderful conclusions with reference to the condition of the planet.

"Processes of the most amazing character are taking place beneath that cloudy envelope, which forms the visible surface of the planet as seen by the terrestrial observer. The real globe of the planet would seem to be intensely heated, perhaps molten, through the fierceness of the heat which pervades it. Masses of vapour streaming continually upward from the surface of this fiery globe would be gathered at once into zones because of their rapid change of distance from the centre. That which is wholly unintelligible when we regard the surface of Jupiter as swept like our earth by polar and equatorial winds, is readily interpreted when we recognize the existence of rapidly uprushing streams of vapour." [Footnote: Mr. Proctor in Monthly Packet, October, 1870.]

Supposing then that the atmosphere of Jupiter is of very great depth, and thus laden with masses of watery vapour, the effect of a sudden current of heated, but comparatively dry, air or gas would be the immediate absorption of the whole or a large portion of the vapour, and the consequent transparency of the portion of the atmosphere affected by it. We see this result continually on a small scale in our own atmosphere, when a heavy cloud comes in contact with a warm air current, and rapidly melts away, Many of the rapid changes which have been witnessed in Jupiter's appearance are readily explained if this view is admitted. Supposing such a thing to have happened near the edge of the disc, the phenomenon recorded by Admiral Smyth is at once satisfactorily explained. When the satellite appeared to pass on to the disc, and to be lost in the light of the planet, it would for some time, proportional to the depth of Jupiter's atmosphere, have behind it a background of clouds only, it would not have entered upon the actual disc of the planet. If then these clouds were suddenly absorbed, the atmosphere behind the satellite would become transparent and invisible, the background would be gone, and the satellite would reappear. In the case of the occultation witnessed by Messrs. Gorton and Wray, the satellite would at first be hidden by cloud only, and would reappear if the cloud were removed. Such seems to be the true explanation of these hitherto mysterious phenomena. That they could not have resulted from any alteration in the motions of the planet or the satellite is evident. Such an alteration would have been instantly detected, since the places of both the planet and the satellites are computed years in advance, and any such change would at once have thrown out all these computations.

Assuming that this is the true solution of the mystery, we are enabled to form an approximate estimate of the extent of the atmosphere of Jupiter. The time between the first and second disappearances does not seem to have been accurately noted. Admiral Smyth's account makes it 16 or 17 minutes; but if we estimate it at 15 minutes only, and if we further assume that the second disappearance was upon the actual disc of Jupiter, and not upon a lower stratum of clouds, we shall be safe from any risk of exaggeration. The probability seems to be that the second disappearance was caused not by the disc, but by the formation of a fresh body of cloud, as it was not gradual, as in the first instance, but sudden. We shall then only have an estimate which cannot be greater, but may be much less, than the true value.

The mean distance of the second satellite from the centre of Jupiter is in round numbers 425,000 miles, and consequently the circumference of its orbit is 2,671,000 miles. The satellite travels through this orbit in about 86 hours, which gives a horary velocity of 31,400 miles, or 7850 miles in 15 minutes. This then is the least possible depth of the atmosphere of Jupiter. [Footnote: For the direction of the motion of the satellite would be at right angles to the line of sight.] The whole diameter of Jupiter, atmosphere and all, is 85,390 miles. Deduct from this 15,700 miles for the atmosphere, and we have for the diameter of the solid nucleus rather less than 70,000 miles. The height of the atmosphere is therefore not less than three-fourteenths of the radius of the planet, and may be much greater. The extent of the atmosphere, combined with the rapidity of rotation, accounts satisfactorily for the great apparent polar compression of the planet. Another inference is that the density of the planet must exceed the ordinary estimate in the proportion of two to one.

But next, the atmosphere of Jupiter is probably of very great density. Dr. Huggins states that he has observed in the spectrum of Jupiter "three or four strong lines, one of them coincident with a strong line in the earth's atmosphere." [Footnote: Lecture at Manchester, November 16, 1870.] Strong lines mark increased density in the absorbent medium, and lines hitherto unobserved indicate new elements. It is therefore probable that the atmosphere of Jupiter is not only much more dense than that of the earth, but also contains some elements--which are absent from the latter. When with this fact we connect the very great extent of the atmosphere, it will be evident that the pressure at the surface of the planet will be enormous, and from this we can form an estimate of the intensity of the forces which must be at work in the interior of the planet, to project jets of vapour through such an atmosphere to so great a height.

The link which connects Jupiter with the earth, in the second stage of its existence, is the mention by Moses of the "waters which were above the firmament." Viewed in the light of the present condition of the earth such a notice seems unaccountable. But if the earth at that time were in a condition similar to that in which Jupiter appears to be now, the water in the atmosphere or above the firmament would be a very important element in any description that might be given of it. It is in fact most probable that all the water (in the strict sense of the word) then in existence would be in a state of vapour, and that the waters which were under the firmament were the molten materials which afterwards formed rocks and ores, since, as has been already noticed, the word is the only one which could be employed to describe fluids in general.

We may now try to form some idea of the probable state of the earth at this period. Its centre would be occupied by a fused mass, in which were blended all the more intractable solid constituents of the present world. This would be surrounded by an atmosphere of very great height and density, containing not only all the present constituents of air, but also all, or nearly all, the water, and all the more volatile of the metals and other elements. Carbonic acid, to a very large extent, would probably be present, and a very considerable proportion of the oxygen which now exists in combination with various bases, and forms by weight so large a proportion of the solid crust of the world.

Owing to the intense heat, chemical combinations would readily be formed between the ingredients of the fused mass and the other elements which existed in the form of vapour, and thus the earliest of the vast variety of existing minerals would be elaborated. The volumes of steam which floated in the upper regions of the atmosphere would rapidly part with their heat by radiation into space, and would descend towards the surface of the earth in the form of rain. At first probably, and for a long time, they would not reach the surface, but as they approached it would be again converted into vapour, and re-ascend to pass again and again through the same process. But by this means the intense heat of the nucleus would be gradually conveyed away, till the cooling reached a point at which some of the superficial materials would assume a solid form. It is by no means certain what is the true primary rock--for a long time it was almost universally assumed to be granite, since granite is uniformly found underlying the oldest sedimentary rocks that are known. But as these rocks have been forced from their original position and tilted up, the underlying stratum may probably be of later date than the upper ones, since it was the elevating agent. So that we can have no certain knowledge on this point, since the earliest sedimentary strata, wherever they retain their original position, must be at a depth far below the reach of man. If, however, Sir C. Kyell's view of the conditions requisite for the formation of granite are correct, these conditions [Footnote: Student's Geology, chap. xxxi.]--heat, moisture, and enormous pressure--would all be present at the surface of the nucleus. Some kind of solid floor must have been formed before the next stage could be reached, at which it would be possible for water to exist in a fluid state. This, however, would be possible at a much higher temperature than at present, owing to the enormous atmospheric pressure. It is possible now, by artificial means, to raise water, nearly if not quite, to a red heat, without the formation of steam, and the pressure of the atmosphere in the case supposed would, in all probability, be much greater than any which we can now apply under the conditions necessary for heating the water.

It is probable that at this point the close of the second day must be placed: but the indications of the narrative do not enable us to fix it with any degree of certainty. As, however, from this point a new series of processes would commence, and those processes are in intimate connexion with the first of the two developments ascribed to the third day, the period when water could first maintain a fluid form on the earth's surface, seems to present the most probable line of demarcation.