Page:Physical Geography of the Sea and its Meteorology.djvu/100

74 way. He makes great use of them. General Sabine, in his passage, some years ago, from Sierra Leone to New York, was drifted one thousand six hundred miles of his way by the force of currents alone; and, since the application of the thermometer to the Gulf Stream, the average passage from England has been reduced from upwards of eight weeks to a little more than four. Some political economists of America have ascribed the great decline of southern commerce which followed the adoption of the Constitution of the United States to the protection given by federal legislation to northern interests. But I think these statements and figures show that this decline was in no small degree owing to the Gulf Stream, the water-thermometer, and the improvements in navigation; for they changed the relations of Charleston—the great southern emporium of the times—removing it from its position as a half-way house, and placing it in the category of an outside station.

191. The scope of these researches.—The plan of our work takes us necessarily into the air, for the sea derives from the winds some of the most striking features in its physical geography; and from the air all of its meteorology. "Without a knowledge of the winds, we can neither understand the navigation of the ocean, nor make ourselves intelligently acquainted with the great highways across it. As with the land, so with the sea; some parts of it are as untravelled and as unknown as the great Amazonian wilderness of Brazil, or the inland basins of Central Africa. To the south of a line extending from Cape Horn to the Cape of Good Hope (Plate VIII.) is an immense waste of waters. None of the commercial thoroughfares of the ocean lead through it; only the adventurous whale-man finds his way there now and then in pursuit of his game; but for all the purposes of science and navigation, it is a vast unknown region. Now, were the prevailing winds of the South Atlantic northerly or southerly instead of easterly or westerly, this unploughed sea would be an oft-used thoroughfare. Nay, more, the sea supplies the wind with food for the rain which these busy messengers convey away from the ocean to "the springs in the valleys which run among the hills." To the philosopher, the places which supply the vapours are as suggestive and as interesting for the instruction they afford, as the places are upon which the vapours are showered down. Therefore, as he who studies the physical geography of the land is expected to make himself acquainted