{44} Here is a problem exactly similar. On examination we find that a certain house is built on a foundation of well-cemented concrete three feet deep, that it has ten courses of stone in the basement, forty courses of brick in the first story, thirty-six courses in the second, thirty-two in the third; with a roof of nine inch rafters, covered with inch boards, and an inch and a half layer of coal-tar and gravel; now tell us how long was the house in building? Why the very school-boy would laugh at the absurdity of such a question. He would say, "How can I tell unless I know where the materials were obtained, how they were conveyed, how many workmen were employed, and how much they could do in a day? If the rock had been brought from a distance, the brick to be made by hand, the lumber all dressed with a handsaw and jackplane, and all the work done by a slowgoing jobbing contractor who employed only three or four men--why, they would not get through in a year. But if the rock was found in excavating the cellar, if the brick were made by machinery and near at hand, the lumber dressed by steam saw and planing mills, and thirty or forty workmen employed, it might be all finished in a month." So the geologist ought to say, "I do not know either the source of the materials of the earth's strata nor the distance from which they were conveyed to their present position, nor the forces which were employed in changing them from their {45} primitive elements to the forms in which we now see them; therefore I cannot tell the time required for their formation. If the crust of the earth was originally fused into granite by intense heat, and this granite has been thrown up into vast mountains by the internal heat of the earth; and in turn, these mountains have been slowly worn away, by the action of wind, rain and frost, and conveyed down to the shores of the primeval ocean, by the still slower agency of mountain torrents and rivers; and if these deposits having first been the home of various species of animals and plants have hardened into rock which in turn has been heaved up by volcanic forces--if this was the mode of creation, hundreds of millions of years may have been required to produce the effects we now see upon the surface of the globe.