brought sediment of strong matter, either because they had transported all the clay from the bottom and sides, and then the waves attacked the rocks, possibly because the first sediment came from one part, and the second from another. This perfectly agrees with observation, by which we perceive that beds of earth, stone, gravel, sand, &c. followed no rule in their arrangement, but are placed indifferently one on the other as it were by chance. But this chance must have some rules, which can be known only by estimating the value of probabilities, and the truth of conjectures. According to our hypothesis, on the formation of the globe, we have seen that the interior part of the globe must have been a vitrified matter, similar to vitrified sand, which is only the fragments of glass, and of which the clays are perhaps the scoria; by this supposition, the centre of the earth, and almost as far as the external circumference, must be glass, or a vitrified matter; and above this we shall find sand, clay, and other scoria. Thus the earth, in its first state, was a nucleus of glass, or vitrified matter; either massive like glass, or divided like sand, because that depends on the degree of heat it has undergone. Above this matter was sand, and lastly clay. The soil of the waters and air produced the external crust, which is thicker or thinner, according to the situation of the ground; more or less coloured, according to the different mixtures of mud, sand, clay, and the decayed parts of animals and vegetables; and more or less fertile, according to the abundance or want of these parts. To shew that this supposition on the formation of sand and clay is not chimerical, I shall add some particular remarks. I conceive, that the earth, in its first state, was a globe, or rather a spheroid of compact glass, covered with a light crust of pumice stone and other scoria of the matter in fusion. The motion and agitation of the waters and air soon reduced this crust into powder or sand, which, by uniting afterwards, produced flints, and owe their hardness, colour, or transparency and variety, to the different degrees of purity of the sand which entered into their composition. These sands, whose constituting parts unite by fire, assimilate, and become very dense, compact, and the more transparent as the sand is more pure; on the contrary, being exposed a long time to the air, they disunite and exfoliate, descend in the form of earth, and it is probable the different clays are thus produced. This dust, sometimes of a brightish yellow, and sometimes like silver, is nothing else but a very pure sand somewhat perished, and almost reduced to an elementary state. By time, particles will be so far attenuated and divided, that they will no longer have power to reflect the light, and acquire all the properties of clay.