CHAP. X. PART III. with the formation of valleys, it is certain, that it is in the highest degree unphilosophical, to suffer ourselves to be so led by them. If we view the subject from higher ground, we must at once disclaim the conclusion. This is a case, in which the contradiction of fact and phænomena, is easily detected. If we had nothing else to consider, but how the earth's surface might be furrowed by streams of water having no reason for their course, it would be of minor consequence to contest the analogy, or to point out its deficiencies. But, there is an essential disparity in the effect; and, therefore, there must be an equal disparity in the cause, of the two operations. The rainwater, which runs down a sloping footpath, works its way at random; it is a matter of indifference, every inch it moves, whether it travels on this side or on that side, in this direction or in that direction. But, how widely different are the directions of the streams and rivers which flow over the surface of the earth, from their sources to their mouths! These are all so skilfully and so equally distributed over that whole surface, for the necessary service of the animal and vegetable creations; so artfully diverted, in many places, from the nearest seas, and conducted through extensive inland regions, as the Danube in Eu CHAP. X. rope, the Ganges in Asia, the Nile in Africa, PART III. and the Amazon in America; that they disclose an irresistible evidence of uniformity of plan and contrivance. The direction of all these rivers is determined, in the first instance, by the direction of the valleys in which they commence their course; the first formation of those valleys must, therefore, in sound philosophy, be ascribed to the Designer and Artificer of the general system so manifestly intended for irrigating the whole surface of the globe; and without which system of irrigation, the entire system of vegetation must necessarily have perished. And, if the vegetable system is to be ascribed to the divine intelligence; how much more rational and philosophical is it to suppose that the correlative irrigating system, to which the formation and direction of valleys and river-beds was as necessary as the formation of arteries and veins to the animal frame, was a corresponding part of the same intelligent ordinance; than that it was effected by the mechanical chance, by which rain trickles down a footway; and that it was by that chance alone, that the vegetable system, created by intelligence, was prevented from perishing through a lack of providence! CHAPTER XI. PART III. THE formation of coal, is a problem which still CHAP. XI. engages the researches and speculations, not of the mineral geology only, but of pure mineralogy and chemistry. M. D'Aubuisson entertains a philosophical doubt, whether this substance ought to be classed with intermediate, or with secondary formations; and he therefore leaves the point undecided. Upon the nature of coal, he defers to the judgment of Mr. Hatchett; whom he duly designates, as "one of the most "able chemists of our time, and who has applied himself, more than any other, to the discovery of the origin of coal." This distinguished chemist pronounces this question to be a difficult problem in the natural history "of minerals.' He states the different opinions, which have been propounded with respect to the origin of this substance; and he then declares his own. 66 The different opinions which Mr. Hatchett 1 Tom. ii. p. 298. Note. 2 Philosoph. Trans. vol. xcvi. p. 135. CHAP. XI. states are these four, of which the first three PART III. are chemical and scientific; the fourth is altogether speculative, and pertains exclusively to the mineral geology, viz.: 1. That coal is a mineral substance - an earth, chiefly argillaceous, impregnated with bitumen. 2. That it is a vegetable substance-consisting of vegetable accumulations, mineralized under vast strata of earth. - con 3. That it is an animal substance sisting of the fat and unctuous matter of marine animals. 4. That it is derived from the primaval chaotic fluid. Mr. Hatchett declares his opinion to coincide with the second of these; and he establishes that opinion upon experiments, accurately made and repeated, in which he obtained coal in large proportion by the action of sulphuric acid upon oak saw-dust. These experiments, have determined the opinions of the best naturalists to regard coal as a mass of vegetable matter; converted, by some natural process, into the substance which it now exhibits. Notwithstanding, however, the success of those experiments, there was always one deficit, rendering the coal imperfect. Mr. Hatchett could CHAP. XI. PART III. never obtain bitumen with his coal; which is nevertheless an essential ingredient in true coal; and he therefore refers the production of bitumen to some unknown process of nature. But, with the deference so justly due to that eminent chemist, I beg leave to suggest; that it would seem to be time enough to resort to that ultimate principle, when all previous research shall have been exhausted; which does not yet appear to be the case. Experiments have indeed been skilfully made on vegetable matter, but it has hitherto been, only on terrestrial vegetable matter. It seems to have been forgotten, in these investigations, that terrestrial vegetation is only one part of universal vegetation; and that immense tracts of marine vegetation flourish in all parts of the bed of the sea. We may judge, from the vast quantity of fuci, and other marine plants vulgarly united under the general denomination of sea-weeds, which are occasionally cast upon some of our coasts, and which are commonly used for fuel in the islands of Jersey and Guernsey, of the immense quantities of these tribes of vegetation which must be contained in the different basins and depths of the sea. Now, since all naturalists are agreed in "this one point, that our present continents |