rocks, no reliable opinion can be formed on mere inspection. Two blocks of marble may appear precisely alike, though formed at different periods. A crystal of carbonate of lime, formed in a few years, would be found quite perfect, and as compact as a crystal formed during many centuries. Nothing can be deduced from the process of petrifaction and crystallisation, unless they enclose relics of a known period. At San Filippo, a solid mass of limestone thirty feet thick has been formed in about twenty years. A hard stratum of travertine a foot thick is obtained, from these thermal springs, in the course of four months. Nor can geologists demonstrate that the Amiens deposits, in which the flint-implements occur, are more than three or four thousand years old.

The causes of these changes and mutations are referred by some persons to floods, or to pre-Adamite convulsions, whereas the cause is in constant operation; they are due to an invisible and subtle power which pervades the air, the ocean, and the rocks below — in which all are wrapped and permeated — which is universally present, namely, magnetism — a power always in operation, always in a state of activity and tension. It has an attractive power towards the surface of the earth, as well as a directive action from pole to pole. " It is, indeed," he adds, emphatically, " the terrestrial gravi-iatio7i. Magnetic needles freely suspended show its meridional or directive polar force, and that the force converges at two opposite parts, which are bounded by the Antarctic and Arctic circles."

This polar force, like a stream, is constantly moving from pole to pole; and experiment proves that this movement is from the South Pole to the North. "Hence the various terrestrial substances, solids and fluids, through which this subtle and universal power permeates, are controlled, propelled, and modified over the entire surface of our globe, commencing at the south and dissolving at the north. Thus, all terrestrial matter moves towards the Arctic region, and finally disappears by dissolution and absorption, to be renewed again and again in the Antarctic Sea to the end of time."

In order to prove that the north polar basin is the receptacle of the final dissolution of all terrestrial substances, Mr. Hopkins quotes the Gulf Stream. Bottles, tropical plants, and wrecks cast into the sea in the South Atlantic, are carried to Greenland in a comparatively •short time. The great tidal waves commence at the fountain-head in the Antarctic circle, impinge against the south coast of Tierra del Fuego, New Zealand, and Tasmania, and are then propelled northward in a series of undulations. The South Atlantic stream, after doubling the Cape of Good Hope, moves towards the Guinea coast.

bends towards the Caribbean Sea, producing the trade winds; again leaves Florida as the Gulf Stream, and washes the coasts of Greenland and Norway, and finally reaches the north polar basin.

Again the great polar force shows itself in the arrangement of the mineral structure below. In all the primary rocks in every quarter of the globe where they have been examined, its action is recognised in giving to the crystalline masses — granites and their laminated elonga-tions— a polar grain and vertical cleavage. " Had it been possible to see our globe stripped of its sedimentary deposits and its oceanic

covering, we shoul'd see it like a gigantic melon, with a uniform grain extending from pole to pole." This structure appears to give polarity to earthquakes — thermal waters and earthquakes — which are all traceable in the direction of the polar grain or cleavage from north to south. In England, for instance, thermal and saline springs are traceable from Bath, through Cheltenham, to Dudley. In Central France, mineral springs occur in lines, more or less, north and south. All the known salt-springs in South America occur in meridional bands. Springs of chloride of sodium in the Eastern Cordilleras stretch from Pinceima to the Llanoes de Meta, a distance of 200 miles. The most productive metalliferous deposits are found in meridional bands. The watery volcanoes in South America are generally situated along the lines of the meridional splits and the secondary eruptive pores on the transverse fractures. The sudden ruptures arising locally from increasing tension of the polar force, and the rapid expansion of the generated gases, produce a vibratory jar in the rocky structure below, which being propagated along the planes of the polar cleavage, gives rise to great superficial oscillations, and thus causes earthquakes and subterranean thunder for thousands of miles, from south to north.

In 1797, the district round the volcano of Tunguraqua in Quito, during one of the great meridional shocks, experienced an undulating movement, which lasted upwards of four minutes, and this was propagated to the shores of the Caribbean Sea.

All these movements demonstrated, according to Mr. Hopkins, that the land as well as the ocean moves from the south pole and north pole, and that the magnetic power has a tendency to proceed from pole to pole in a spiral path from south-east to north-west, a movement which produces an apparent change in the equinoxes, or the outer section of the plane of the ecliptic with the equator, a phenomenon known to astronomers as the precession of the equinoxes.

Such is a very brief summary of the arguments by which Mr. Evan Hopkins maintains the Uteral correctness of the Mosaic account of the creation, and attempts to show that all the facts discovered by geologists may have occurred in the ages included in the Mosaic chronology. That the mysterious power of terrestrial magnetism can perform all that he claims for it, we can perhaps admit. But how does this explain the succession of Silurian, Old Red Sandstone, Carboniferous and other strata, up to the Tertiary deposits, with their fossils, each differing in character from those of the preceding series? That these were successive creations admits of no doubt, and while it is undeniable that the fiat of the Creator could readily produce all these phenomena, it may reasonably be asked if it is probable that all these myriads of organic beings, whose remains serve as records of their existence, were created only to be immediately destroyed.

Again, does not the author of the " Principles of Terrestrial Physics" prove too much? He admits that 3,000 years ago the climate of En[!],and was tropical: he does not deny that a subsequent period of intense cold intervened, 2,550 years ago. He admits historical records, and 2,350 years ago Pythagoras constructed his cosmography of the world, which has never been seriously im-pugned;and yet he has no suspicion that countries so near to his own had changed their climates first from tropical to glacial, and back again to a temperate zone. It is not reasonable to believe this parable. The school of philosophy generally considered to be the most advanced in modem science has yet another view of cosmogony, of which we venture to give a brief outline. Space is infinite, says the exponent of this system,* for wherever in imagination we erect a boundary, we are compelled to think of space as existing beyond it. The starry heavens proclaim that it is not entirely void; but the question remains, are the vast regions which surround the stars, and across which light is propagated, absolutely empty? No. Modern science, while it rejects the notion of the luminiferous particles of the old philosophy, has cogent proofs of the existence of a luminiferous ether with definite mechanical properties. It is infinitely more at-tenuated, but more solid than gas. It resembles jelly rather than air, and if not co-extensive with space, it extends as far as the most distant star the telescope reveals to us; it is the vehicle of their light in fact; it takes up their molecular tremors and conveys them with

• Professor Tyndall in Fortnightly Review,

inconceivable rapidity to our organs of vision. The splendour of the firmament at night is due to this vibration. If this ether has a boundary, masses of ponderable matter may exist beyond it, but they could emit no light. Dark suns may burn there, metals may be heated to fusion in invisible furnaces, planets may be molten amid intense darkness; for the loss of heat being simply the abstraction of molecular motion by the ether, where this medium is absent no cooling could take place. This, however, does not concern us; as far as our knowledge of space extends, we are to conceive of it as the holder of this luminiferous ether, through which the fixed stars are interspersed at enormous distances apart. Associated with our planet we have a group of dark planetary masses revolving at various distances around it, each rotating on its axis; and, connected with them, their moons. Was space furnished at once, by the fiat of Omnipotence, with these burning orbs? The man of science should give no answer to this question: but he has better materials to guide him than anybody else, and can clearly show that the present state of things inay be derivative. He can perhaps assign reasons which render it probable that it is derivative. The law of gravitation enunciated by Newton is, that every particle of matter in the universe attracts every other particle with a force which diminishes as the square of the distance increases. Under this law a stone falls to the ground, and heat is produced by the shock; meteors plunge into the atmosphere and become incandescent; showers of such doubtless fall incessantly upon the sun, and were it stopped in its orbit, the earth would rush towards the sun, developing heat in the collision (according to the calculations of MM. Joule, Mayer, Helmholtz, and Thomson), equal to the combustion of five thousand worlds of solid coal. In the attraction of gravity, therefore, acting upon this luminous matter, we have a source of heat more powerful than could be derived from any terrestrial combustion. To the above conception of space we must add that of its being in a continual state of tremor. The sources of vibration are the ponderable masses of the universe. Our own planet is an aggregate of solids, liquids, and gases. On closer examination, these are found to be composed of still more elementary parts: the water of our rivers is formed by the union, in definite proportions, of two gases, oxygen and hydrogen. So, likewise, our chalk hills are formed by a combination of carbon, oxygen, and calcium; elements which in definite proportions form chalk. The flint found within that chalk is compounded of oxygen and silicon, and our ordinary clay is for the most

part formed by a union of silicon, oxygen, and aluminum. By far the greater part of the earthy crust is thus compounded of a few elementary substances. Such is Professor Tyndall's view of the universe, rising incidentally out of his theory of heat, his main object being to elucidate his theory of heat and light.

Modifications of the Surface of the Globe.

As a consequence of the hypothesis of central heat, it is admitted that our planet has been agitated by a series of local disturbances; that is to say, by ruptures of its solid crust occurring at more or less distant intervals. These partial revolutions at the surface are supposed to have been produced, as we shall have occasion to explain, by upheavals or depressions of the solid crust, resulting from the fluidity of the central parts, and by the cooling down of the external crust of the globe. Almost all bodies, in passing from a liquid to a solid state, are diminished in size in the process. In molten metals which resume the solid state by cooling, this diminution amounts to about a tenth of their volume; but the decrease in size is not equal throughout the whole mass. Hence, as a result of the solidification of the internal parts of the globe, the outer envelope would be too large; and would no longer fit the inner sphere, which had contracted in cooling. Cracks and hollows occur under such circumstances, even in small masses, and the effect of converting such a vast body as the earth from a liquid, or rather molten condition, to a solid state, may be imagined. As the interior became solid and concrete by cooling, furrows, corrugations, and depressions in the external crust of the globe would occur, causing great inequalities in its surface; producing, in short, what are now called chains of mountains.

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