“Where art has not diverted the order of things and nature is left to herself, a considerable locality may be observed in many animals and vegetables as well as mineral productions, by which they evidently attached to particular soils to such a degree that, if this subject were studied with attention, it would form one of the principal external characteristics of the strata underneath. Though it may seem mysterious to some, that birds, beasts, insects, etc., which have the liberty of roving at pleasure, should feel any particular attachment for this or that soil, yet the wonder ceases when we consider how the chain of natural things is linked together, and how these creatures are taught to cull their food from insects that are lodged in, or seeds that are produced from, particular plants that grow upon particular soils.” Smith had seen layers of limestone crowded with shells succeeded by others containing corals. He found ammonites and oysters in some, and insect remains in others, and his speculations assumed the curious phase of the sentences just noticed. But he soon became aware that accident had much to do with the presence of certain organic remains in strata, and that, whilst some fossils, like corals, once lived where they are now preserved in strata, others were carried there as the deposit collected. A manuscript, dated December 2, 1796, Dunkerton, Swan Inn, headed “Strata in general, and their position,” and evidently intended for publication, commences thus:— “The strata being found as regular on one side of a rivulet, river, deep valley or channel as on the other, over an extent of many miles, when proper allowance is made for the inclination, and for the variation of the surface, is it not reasonable to suppose that the same strata may be found as regular on one side of the sea or ocean as on opposite sides of a deep valley upon land, and if so, and the continuation of the strata is general, what is their general direction or drift? Is it in straight lines from pole to pole, or in curved lines surrounding the globe regularly inclined to the east?” After hinting at a general cause for such an assumed regularity, he adds, “But all theories are best built on practical rules, which will enable any one to make such observations for himself as must carry conviction along with them; for a work so novel as this must expect to find some who will hardly believe what is plain to be seen; for all men do not see alike, nor can patiently trudge through the dirt to search for truth among the stubborn rocks where nature has best displayed her.... Shall, therefore, describe a number of quarries, cliffs, etc., at a great distance, etc. See Book——” In what seems to be the continuation of this paper, we see the predominant desire of the author to establish the certainty and generality of the inclination of strata, which he had proved on a limited scale near Bath.