it is true, and their routes cannot be ascertained. But knowing where they were cast, and seeing where they are found, some idea may be formed as to their course. Straight lines may at least be drawn, showing the shortest distance from the beginning to the end of their voyage, with the time elapsed. Captain Becher, R.N., has prepared a chart representing in this way the tracks of more than one hundred bottles. From this chart it appears that the waters from every quarter of the Atlantic tend toward the Gulf of Mexico and its stream. Bottles cast into the sea midway between the Old and the New Worlds, near the coasts of Europe, Africa, and America, at the extreme north or farthest south, have been found either in the West Indies, on the British Isles, or within the well-known range of Gulf Stream waters.
87. Their drift.—Of two cast out together in south latitude on the coast of Africa, one was found on the island of Trinidad; the other on Guernsey, in the English Channel. In the absence of positive information on the subject, the circumstantial evidence that the latter performed the tour of the Gulf is all but conclusive. And there is reason to suppose that some of the bottles of the gallant captain's chart have also performed the tour of the Gulf Stream; then, without being cast ashore, have returned with the drift along the coast of Africa into the inter-tropical region; thence through the Caribbean Sea, and so on with the Gulf Stream again. (Plate VI.) Another bottle, said to be thrown over off Cape Horn by an American ship-master in 1837, was afterwards picked up on the coast of Ireland. An inspection of the chart, and of the drift of the other bottles, seems to force the conclusion that this bottle too went even from that remote region to the so-called higher level of the Gulf Stream reservoir.
88. The Sargasso Sea.—Midway the Atlantic, in the triangular space between the Azores, Canaries, and the Cape de Verd Islands, is the great Sargasso Sea. (Plate VI.) Covering an area equal in extent to the Mississippi Valley, it is so thickly matted over with Gulf weed (Fucus natans) that the speed of vessels passing through it is often much retarded. When the companions of Columbus saw it, they thought it marked the limits of navigation, and became alarmed. To the eye, at a little distance, it seems substantial enough to walk upon. Patches of the weed are generally to be seen floating along the outer edge of the Gulf Stream. The sea-weed always "tails to" a steady or a constant wind, so that it serves the mariner as a sort of marine anemo-
