The Mediterranean is like a bag with two necks filling at both ends. The current through the Dardanelles presents exciting varieties, but no perplexing mysteries. It is the discharge of the surplus of the Black Sea, and the current is subject to the influences of the northerly and southerly winds; being reversed when the latter long prevails. At Gibraltar all is disorder--the stream incessant--the level on both sides the same. The tide rises and falls, yet the current always runs out of the ocean and into the Mediterranean. So determined is this rush, that the gales of the Equinox neither quicken nor retard it, and the phases of the moon have no power over it. It bursts through all obstacles and transgresses all laws, and seems to move by a will of its own--too strong to be disturbed, too deep to be discovered. During my excursions I was engaged in examining these phenomena, and I will commence with stating the results of several months’ cogitation and inquiries. I first applied myself to test the old explanation of an under-current, by endeavouring to float substances at various levels, and after great trouble in procuring lines, and having machines of various kinds made, I found that without a frigate’s tackle and crew no results could be obtained. I was thus reduced to mere scrutiny of the alleged facts, and of the alleged theory. The facts amount to this: a vessel, in 1754,[24] was fired into from the battery, it sank in face of the rock, and was afterwards cast up in the bay of Tangier. A vessel, when it sinks, goes to the bottom, and if fragments of it are detached and are cast ashore, it is only because they float, that is, they rise to the surface. This story will not, therefore, serve the theory, even if authentic. There is nothing to prevent a ship or timber from floating out; for close in shore, on both sides, the tides of the ocean rise within the Straits to the height of four feet: of these, boats take advantage to get through against both wind and current. Sometimes, indeed, though it very rarely happens, the whole current is reversed; and vessels working during the night, and reckoning on being carried fifty miles to the eastward, have found themselves in the morning ninety miles to the westward of the point where they expected to be, that is to say, carried forty miles over the ground to the westward during the night.[25] Having thus disposed of the only, but incessantly quoted fact, I proceed to the theory. Reasoning, however, there is none, for it amounts to nothing more than this: “What becomes of all this water? It cannot go to the Black Sea, from which the Mediterranean receives water; it cannot escape by a subterranean passage into the Red Sea, for the level of the Red Sea is higher by thirty feet. Then there is an under-current discharging the water back again into the ocean.”