of deposition in water, being the burial-ground of the time of its collection or formation. Fossils were thus shown by Steno to be mineralized or petrified organic remains, and he gave the hint or method to future investigators, that the example of the existing animals must be taken, in order to learn the nature of those creatures whose remains are more or less perfectly preserved in the fossil condition. Following out this subject, Steno wrote on the manner in which deposits accumulate, and accumulated in past ages; and he concluded that if we found a deposit containing sea-salt and the remains of marine animals, planks of ships etc., we should believe that the sea had once been there, whether the bed was exposed in consequence of the sea having retired, or because the land had been raised. He showed that although the lowest beds deposited over any area, must conform to the shape of the underlying rock, the tendency of all sediment must be to occupy the horizontal position; and so when we find them highly inclined, as in mountains, for instance, we must refer this to subsequent movement. He noticed that mountains are made up both of horizontal and inclined strata, as may be seen along their flanks. He infers that mountains were once not in existence, and that they do not grow, but that their regions are raised and depressed and subject to rending and fissuring. Steno clearly showed that the land had sunk and had been again elevated in the geological ages, and in considering the causes he seems to have grasped the idea that the internal heat of the earth becoming less, the mass cools, and that the movements on the surface have had to do with the cooling. His most important work was removing fossils out of the category of marvels, sports of nature, and as things which grew in the earth, to the proper truth that they are preserved parts of animals and plants which were formerly alive. In 1688, Steno was appointed to the chair of anatomy at Copenhagen; but he had to suffer from jealousy, and doubtless some religious persecution influenced his desire to leave his native country and to return to Florence again. This he did, and Cosmo III. entrusted him with the education of his son. Steno then began to give up science and to study theology, and wrote several works on the subject by which he hoped to convert his old natural history friends. One of these involved him in a controversy with the reformed clergy of Jena. The Pope, Innocent XI., rewarded Steno in 1677, by making him a bishop and apostolic vicar of Northern Europe. Steno went to reside at Hanover; but he had to leave, and returning to Schwerin, he died there. His body was, at the request of the Grand Duke Cosmo, carried back to Tuscany in 1687. [Illustration] [Illustration] CHAPTER X. THE LIFE OF HUTTON.