found ten degrees warmer than the air. [Footnote 189: Geography of Herodotus, p. 672.] 374. The course of the Gulf stream is so fixed and regular, that nuts and plants from the West Indies are annually thrown ashore on the Western Islands of Scotland. The mast of a man of war, burnt at Jamaica, was driven several months afterwards on the Hebrides,[190] after performing a voyage of more than 4000 miles, under the direction of a current, which, in the midst of the ocean, maintains its course as steadily as a river does upon the land. [Footnote 190: Pennant's Arctic Zoology, Introd. p. 70.] The great system of currents thus traced through the Atlantic, has no doubt phenomena corresponding to it in the Indian and Pacific Oceans, which the industry of future navigators may discover. The whole appears to be connected with the trade winds, the figure of our continents, the temperature of the seas themselves, and perhaps with some inequalities in the structure of the globe. The disturbance produced by these causes in the equilibrium of the sea, probably reaches to the very bottom of it, and gives rise to those counter currents, which have sometimes been discovered at great depths under the surface.[191] [Footnote 191: Histoire Naturelle de Buffon, Supplément, tom. ix. p. 479. 8vo.] The great transportation of materials that must result from the action of these combined currents is obvious, and serves not a little to diminish our wonder, at finding the productions of one climate so frequently included among the fossils of another. Amid all the revolutions of the globe, the economy of nature has been uniform, in this respect, as well as in so many others, and her laws are the only thing that have resisted the general movement. The rivers and the rocks, the seas and the continents, have been changed in all their parts; but the laws which direct those changes, and the rules to which they are subject, have remained invariably the same. 375. Objections have been made to that translation of materials by the waters of the ocean which is supposed in this theory, particularly by Mr Kirwan, in his Geological Essays; and, though I might perhaps content myself with the remark already made, that the Neptunian system involves suppositions concerning the transportation of solid bodies by the sea, in the early ages of the world, as wonderful as those which, according to our theory, are common to all ages, I am unwilling to remain satisfied with a mere _argumentum ad hominem_, where the fallacy of the reasoning is so easily detected. 376. One of Mr Kirwan's objections to the deposition of materials at the bottom of the sea, is thus stated: "FRISI has remarked, in his mathematical discourses, that if any considerable mass of matter were accumulated in the interior of the ocean, the diurnal motion of the globe would be disturbed, and consequently it would be perceptible; a phenomenon, however, of which no history or tradition gives any account."[192]