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 Europe, the Ganges in Asia, the Nile in Africa, 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; without which system of irrigation, the entire system of vegetation must necessarily have perished. If, then, the vegetable system is to be ascribed to the Divine intelligence; how much more philosophical and rational is it to admit, that the correlative irrigating system, to which the formation and direction of valleys and river-beds was as essentially necessary as the formation and direction. of arteries and veins to the animal system, was a corresponding part of the same intelligent ordinance; than to suppose, that it was effected by the same 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!

If, moreover, we examine the beds of rivers, we shall find, even where they consist entirely of pebbles, that they are covered with a viscous or slimy matter; by which provision, they are sheathed against that very action of the water to which the mineral geology would ascribe their original excavation. And we shall thus be certified; that the artificer of the channels was not the subjected fluid, but, that it was HE who has thus protected the channels against the erosive power of the fluid which He has ordained to flow within them.

CHAPTER XI.

THE formation of Coal, is a problem which still engages the researches and speculations, not of the mineral geology only, but also of pure Mineralogy and Chemistry; and it will be found a subject of deep interest, both philosophical and historical, in the inquiry which we are now pursuing. M. D'Aubuisson, in the body of his "Traité de

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Géognosie," entertains a doubt, (which he afterwards determines for himself in his "Table des

matières,") whether this substance ought to be classed with intermediary or with secondary formations; to one or other of which, it has been variously referred by different mineralogists; and he therefore leaves the point, for the present, undecided. Upon the nature and origin of coal, he defers to the judgment of Mr. Hatchett; whom he duly designates "one of the most able che"mists of our time, and who has applied himself,

more than any other, to the discovery of the origin of coal1." That distinguished chemist, pronounces this question to be "a difficult pro"blem 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.

Tom. ii. p. 298, note.

2 Phil. Trans. vol. xcvi. p. 135.

The different opinions which Mr. Hatchett states, are these four, of which the first three are chemical and scientific: the fourth, is altogether speculative and imaginary, and pertains exclusively to the mineral geology, viz. :

1. That coal is a mineral substance-an earth, chiefly argillaceous, impregnated with bitu

men.

2. That it is a vegetable substance-consisting of vegetable accumulations, mineralised under vast strata of earth.

3. That it is an animal substance-consisting of the fat and unctuous matter of marine animals.

4. That it is derived from the primeval 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 carbon or coal, in large proportion, by the action of sulphuric acid upon oak saw-dust; which opinion, has been powerfully supported by the later skilful experiments and conclusions of Dr. Mac Culloch. Those experiments have determined the opinions of the best naturalists, both at home and abroad, 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

which rendered the coal imperfect. Mr. Hatchett could never obtain bitumen with his carbonated oak saw-dust', which substance is nevertheless an essential ingredient in true coal; and he therefore concluded, by entirely referring the production of the bitumen to some unknown process of nature in the transmutation of wood.

But, with all the deference which is so justly due to that eminent chemist, I must beg leave to suggest; that it would seem to be time enough to resort to that ultimate principle when all previous means of research shall have been exhausted, which does not yet appear to be the case. Experiments have, indeed, been skilfully made on vegetable matter; but, they have hitherto been made only on terrestrial vegetable matter. It seems to have been entirely 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 form a sufficient judgment, from the vast quantity of fuci and other marine plants vulgarly united under the denomination of sea-weeds, which are continually cast upon 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 that must be contained in the different basins

1 Dr. Mac Culloch's able experiments, do not appear to have been attended with more positive and practical success in this particular. Geol. Trans. vol. ii.