"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.