sections illustrating the Genesis of the Earth.

Fig. 1. A vaporous world.

Fig. 2. A world with a central fluid nucleus (b) and a photosphere (a).

Fig. 3. The photosphere darkened, and a solid crust (c) and solid nucleus (d) formed.

Fig. 4. Water (e) deposited on the crust, forming a universal ocean.

Fig. 5. The crust crumpled by shrinkage, land elevated, and the water occupying the intervening depressions.

The figures are all of uniform size; but the circle (A) shows th diameter of the globe when in the state of fig. 1, and that marked (B) its diameter when in the state of fig. 5. In all the figures (a) represents vapour or air; (b) liquid rock; (c) solid rock as a crust; (d) solid nucleus; (e) water.

Such considerations lead to the conclusion that the former watery condition of our planet was not its first state, and that we must trace it back to a previous reign of fire. The reasons which can be adduced in support of this are no doubt somewhat vague, and may in their details be variously interpreted; but at present we have no other interpretation to give of that chaos, formless and void, that state in which “nor aught nor nought existed,” which the sacred writings and the traditions and poetry of ancient nations concur with modern science in indicating as the primitive state of the earth.

Let our first picture, then, be that of a vaporous mass, representing our now solid planet spread out over a space nearly two thousand times greater in diameter than that which it now occupies, and whirling in its annual round about the still vaporous centre of our system, in which at an earlier period the earth had been but an exterior layer, or ring of vapour. The atoms that now constitute the most solid rocks are in this state as tenuous as air, kept apart by the expansive force of heat, which prevents not only their mechanical union, but also their chemical combination. But within the mass, slowly and silently, the force of gravitation is compressing the particles in its giant hand, and gathering the denser toward the centre, while heat is given forth on all sides from the condensing mass into the voids of space without. Little by little the denser and less volatile matters collect in the centre as a fluid molten globe, the nucleus of the future planet; and in this nucleus the elements, obeying their chemical affinities hitherto latent, are arranging themselves in compounds which are to constitute the future rocks. At the same time, in the exterior of the vaporous envelope, matters cooled by radiation into the space without, are combining with each other, and are being precipitated in earthy rain or snow into the seething mass within, where they are either again vaporised and sent to the surface or absorbed in the increasing nucleus. As this process advances, a new brilliancy is given to the faint shining of the nebulous matter by the incandescence of these solid particles in the upper layers of its atmosphere, a condition which at this moment, on a greater scale, is that of the sun; in the case of the earth, so much smaller in volume, and farther from the centre of the system, it came on earlier, and has long since passed away. This was the glorious starlike condition of our globe: in a physical point of view, its most perfect and beautiful state, when, if there were astronomers with telescopes in the stars, they might have seen our now dull earth flash forth—a brilliant white star secondary to the sun.

But in process of time this passes away. All the more solid and less volatile substances are condensed and precipitated; and now the atmosphere, still vast in bulk, and dark and misty in texture, contains only the water, chlorine, carbonic acid, sulphuric acid, and other more volatile substances; and as these gather in dense clouds at the outer surface, and pour in fierce corrosive rains upon the heated nucleus, combining with its materials, or flashing again into vapour, darkness dense and gross settles upon the vaporous deep, and continues for long ages, until the atmosphere is finally cleared of its acid vapours and its superfluous waters.[B] In the meantime, radiation, and the heat abstracted from the liquid nucleus by the showers of condensing material from the atmosphere, have so far cooled its surface that a crust of slag or cinder forms upon it. Broken again and again by the heavings of the ocean of fire, it at length sets permanently, and receives upon its bare and blistered surface the ever-increasing aqueous and acid rain thrown down from the atmosphere, at first sending it all hissing and steaming back, but at length allowing it to remain a universal boiling ocean. Then began the reign of the waters, and the dominion of fire was confined to the abysses within the solid crust. Under the primeval ocean were formed the first stratified rocks, from the substances precipitated from its waters, which must have been loaded with solid matter. We must not imagine this primeval ocean like our own blue sea, clear and transparent, but filled with earthy and saline matters, thick and turbid, until these were permitted to settle to the bottom and form the first sediments. The several changes above referred to are represented in diagrammatic form in figs. 1 to 4.

In the meantime all is not at rest in the interior of the new-formed earth. Under the crust vast oceans of molten rock may still remain, but a solid interior nucleus is being crystallised in the centre, and the whole interior globe is gradually shrinking. At length this process advances so far that the exterior crust, like a sheet of ice from below which the water has subsided, is left unsupported; and with terrible earthquake-throes it sinks downward, wrinkling up into huge folds, between which are vast sunken areas into which the waters subside, while from the intervening ridges the earth’s pent-up fires belch forth ashes and molten rocks. (Fig. 5.) So arose the first dry land:—

"The mountains huge appear Emergent, and their broad bare backs upheave Into the clouds, their tops ascend the sky, So high as heaved the tumid hills, so low Down sunk a hollow bottom, broad and deep, Capacious bed of waters."

The cloud was its garment, it was swathed in thick darkness, and presented but a rugged pile of rocky precipices; yet well might the “morning stars sing together, and all the sons of God shout with joy,” when its foundations were settled and its corner-stone laid, for then were inaugurated the changes which were to lead to the introduction of life on the earth, and to all the future development of the continents.

Physical geographers have taught us that the great continents, whether we regard their coasts or their mountain chains, are built up on lines which run north-east and south-west, and north-west and south-east; and it is also observed that these lines are great circles of the earth tangent to the polar circle. Further, we find, as a result of geological investigation, that these lines determined the deposition and the elevation of the oldest rocks known to us.