as an attraction from above downwards, or from below upwards, to a common center. Gravity is the general law of nature. The planets, the comets, the sun, the earth, are all subject to its laws. The centrifugal force, or force of impulsion, is still unknown: but it is evident, as the attractive force continually draws all the planets towards the sun, they would fall in a perpendicular line into that luminary, if they were not kept at a distance by some other power, forcing them to meet in a straight line. If again this impulsive force were not counteracted by that of attraction, all the planets would fly off in the tangents of their respective orbits. The motions both of planets and comets are regulated by impulsive and attractive force, continually acting and obliging them to describe curves. May we not conjecture, therefore," says Buffon, "that a comet falling into the body of the sun, might drive off some parts from its surface, and communicate to them a violent impulsive force, which they still retain? The earth, when it issued from the sun, was liquid fire. When it cooled, the vapours, condensed, fell down in the form of water upon the surface, depositing at the same time a slimy substance mixed with sulphur and salts, part of which was carried by the motion of the waters into the perpendicular fissures of the strata, strata, and produced metals, and the rest remained on the surface, and gave rise to vegetable mould, with more or less of animal and vegetable particles. Thus the interior parts of the globe were originally composed of vitrified matter, and they continue so at present. Above these were placed those bodies which the fire had reduced into the smallest particles, as sands, which are only portions of glass; and above these, pumice stones, and the scoriæ of melted. matter, which gave rise to the different clays. The whole was covered with water to the depth of five hundred or six hundred feet. This water deposited a stratum of mud, mixed with all those matters which are capable of being sublimed or exhaled by fire; and the air was formed of the most subtile vapours, which, from their levity, rose above the water." "Such was the condition of the earth, when the tides, the winds, and the heat of the sun began to introduce changes on its surface. The diurnal motion of the earth, and that of the tides, elevated the waters in the equatorial regions, and necessarily transported thither great quantities of slime, clay, and sand, and by thus elevating these parts of the earth, sunk those under the poles about two leagues. The strata are not arranged according D4 according to their specific gravities. Beds of heavy matter are frequently placed above those of lighter. Rocks are often upon clay and sand. Glass appears to be the true elementary earth, and all mixed bodies are only glass in disguise. Every grain of sand may be considered as a small flint, and every piece of flint as a collection of fine sand cemented together. The quartz is perfectly transparent flint, and in decomposing, produces soft talcs, or stones, composed of plates, generally parallel, flexible, and elastic. Great mountains, which are composed of vitrescent materials, and produced by the action of the primitive fire, are immediately connected with the interior rock of the globe, which is also a vitreous rock of the same kind. Every material of which this globe is composed, might in a word be in general reduced to its primitive state of glass, if a sufficient degree of heat were to be applied." "The great inequalities of this globe," continues Buffon, "took place when it assumed its form and consistence; swellings and blisters arising, as in the case of a block of glass or melted matter. In the action of cooling, it was furrowed with depths and eminences. The vitrescent matter, of which the rock of the globe is composed, and all the nuclei of mountains, were produced by the primitive fire. The waters have only formed the accessory strata, which surrounded the nuclei horizontally, and in which are the relics of shells and other productions of the ocean. Shells never having been found on the highest mountains," says Buffon, "nor any where much above two thousand fathoms above the level of the sea, it is clear that the waters never surmounted those high summits, or at least remained but a short time upon them. They only formed hills and calcareous mountains, which never rise to much more than the height of two thousand fathoms." "The earth possesses an internal heat," continues this naturalist, "which is peculiar to itself. The heat conveyed from the sun is small, and would not be alone sufficient to support animated nature. At equal depths this internal heat is invariably the same, and it appears to augment in proportion as you descend. The constituent parts of the globe are homogeneous. All the particles are united by mutual attraction. Every particle, therefore, is a center, and there is no reason to believe that the parts which surround the center, are denser than those which surround any other Part neither should it be imagined, imagined, that the interior parts of the earth are hollow; they are composed of matter of considerable density, nearly similar to that of its surface." Such, in brief, is the skeleton of Buffon's system. I have not conceived it of importance to exhibit the subject in its full proportions. The investigation would have been tedious; and the display, however in its detail beautiful, too feebly supported by clear and probable reasonings, to be otherwise amusing, than as the fairy wanderings of an ardent and fertile imagination. The physical objections to Buffon's system are strikingly apparent. As to the fragment dashed from the sun-this I shall leave to be examined by others. The manner of accounting for the oblate spheroidical figure of the globe, may deserve your consideration. Mathematicians have different methods by which they explain this figure.* The great Newton deduced it from a centrifugal force, and the French philosopher, with various others, have followed him. But, notwithstanding such high authority, it has been contended, that we should never treat of * Jones's Philosophy of the Elements. this |