I nevertheless acknowledge that this time, all considerable as it is, does not appear sufficiently long for certain changes, certain successive alterations, which Natural History demonstrates to have taken place, and which seem to have required a still longer course of centuries; and from which I should be inclined to imagine, that, in reality, this time would be increased perhaps double if every phenomena were completely investigated; but I have confined myself to the least terms, and restrained, the limits of time as much as possible, without contradicting facts and experiments. This theory, perhaps, may be attacked by another objection, which it is right to guard against. It may be told me that I have supposed, after Newton, the heat of boiling water to be three times greater than that of the sun in summer, and iron heated red-hot eight times greater than boiling water, that is, 24 or 25 times greater than that of the actual temperature of the earth, and that there is something hypothetical in this supposition, on which I have founded the second basis of my calculations, whose results would be, without doubt, very different if this red heat of iron, or glass in incandescence, instead of being, in fact, 25 times greater than the actual heat of the globe, were, for example only 5 or 6 times as great. The better to feel the force of this objection, let us make a calculation of the refrigeration of the earth, upon the supposition that in the time of incandescence it was only five times hotter than it is according to our calculations; this solar heat, instead of a compensation of 1/50 would have only made the compensation of 1/250 in the time of incandescence, these two terms added together gives 6/250, which multiplied by 2-1/2, the half of the sum of all the terms of the diminution of heat, gives 15/250 for the total compensation which the heat of the sun has made during the whole period of the deperdition of the innate heat of the globe, which is 74047 years: therefore we shall have : 15/250 :: 74047 : 888-14/25 from which we see that the prolongation of refrigeration, which for a heat 28 times greater than actual temperature, has been only 770 years, should have been 888-14/25 in the supposition that this first heat should have been only five times greater than this actual temperature. This alone shews us that if we even suppose this primitive heat below 25, there would only be a longer prolongation of the refrigeration of the globe, and that alone appears to me sufficient to satisfy the objection.