The Mosaic record of the creation cf the second day portrays the formation of the firmament or atmosphere in language strangely accurate for one who, like Moses, must have been ignorant, not merely of the nature and offices of our atmosphere, but of its very existence. The Hebrew word which has been translated firmament' means expanse;' and there was no other word in the language de scriptive of that which divides the waters which were above, in the clouds, from the waters which were below, upon the earth. The use of the ex pression, therefore, denotes their ignorance of that beauteous structure which is designated by our term the atmosphere ;' and yet one out of the six days of the creation is set apart by Moses for its construction. On that day, therefore, the elastic fluid of the atmosphere was wrapped around our globe ; and that it must have come into existence before the end of the Silurian era, is manifest from the fact of vertebrate fish having sported in the Silurian seas, inasmuch as animals of that descrip tion require the assistance of air to support their bodies in swimming through the waters. Land vegetation also appeared simultaneously with the fish, and atmospheric air was necessary for its exist ence.
The system that succeeded the Silurian was that in which the Devonian or Old Red Sandstone rocks were formed ; and all geologists concur in stating, that the position in which these rocks are found indicates that the era was ushered in by violent commotions, during which most of the principal mountain ranges in the world were thrown up. The fossil remains of this era, during which sedi mentary rocks, which are calculated to be about to,000 feet in thickness, were formed, present to our view, in addition to the previous existing orders of animals, vertebrate fish of the Placoid and Ganoid species. These have been graphically described by Hugh Miller, in The Old Red Sandstone,' as cartilaginous, and clad in strong integuments of bone composed of enamelled plates, instead of the horny scales which form the covering of the fish of the present day ; and it has been suggested by Dr. Buckland, that this hard coating may have formed a defence against the injurious effects of water of a high temperature. The first traces of land vegetation have been found at the top of the Silurian, where the Old Red Sandstone rests on it, a circumstance that, coupled with the remarkable terrestrial convulsion which prevailed at the com mencement of the system, confirms the Mosaic description of the work of the third day, viz., the first appearance of dry land above the waters, and the bringing forth of grass, herbs, and trees yield ing fruit, each after its kind. The fossil remains
of a small reptile, which is stated to have been found in a rock at the top of the Old Red Sand stone, have been supposed to be the first traces of terrestrial life upon the globe ; but Professor Owen is of opinion, that the rock in question does not belong to the Old Red Sandstone formation, but to another long subsequent—the Trias.
The system that succeeded the Devonian is the Carboniferous, which is one of importance and in terest to mankind, as having been the period of the formation of coal, iron, and the mountain limestone —a combination of products that have contri buted so largely, in these latter days, to the comfort and convenience of the human race. The coal measures, it is well ascertained, are the produce of profuse and extensive vegetation, and the nature of the plants of which it has been formed, are easily discoverable by a close examination of the mineral itself, which, on inspection, discloses them to have been almost entirely of the cryptogamic order, and such as would be produced in abundance in posi tions of shade, heat, and humidity. Ferns, cala mites, and esquisitaceous plants preponderate, and wood of hard and ligneous tissue, which is, in a great measure, dependent on the unshaded light of the sunbeam, is of rare occurrence in this forma tion—while season rings, which result from the impact of the direct rays of sunlight on the tree, are not found at all in the fossil woods of this or the previous formation, though they appear in those of the succeeding systems. These phenomena (among others) indicate that, throughout the car boniferous era, the vapours that had been lifted up and sustained by the atmosphere from the time of its formation, had not been penetrated by the rays of the sun ; or, more properly speaking, the clouds had remained unbroken between the sun and the earth ; and at, or soon after its close, there must have been an increase of the luminous principle. Until the central heat had cooled down, the clouds that had been formed and fed by the steaming vapours of the tepid waters of the globe, must have continued to intercept the rays of the sun ; and until they were dissolved, as we have reason to know they were at the close of the carboniferous era, the celestial bodies must have been invisible to an earthly eve. But the veil of clouds having passed away, letting in the unclouded light of the sun, moon, and stars, and thereby revealing their orbs to earthly eyes, the accuracy of the Mosaic descrip tion of the first appearance of those heavenly bodies at this time, to be from thenceforth ' for signs and for seasons, and for days and years,' has been fully vindicated.