GULF STEEAM, CLIMATES, AND COMSIEKCE. 71 



passage, souig ^'ears ago, from Sierra Leone to Nevv York, was 

 diifted one tlionsand six linndred miles of liis way by the force ot 

 cuiTents alone; and, since tlie application of the thermometer to 

 the Gulf Stream, the average passage fi^om England has been 

 reduced fi'om upwards of eight weeks to a little more than four. 

 Some political economists of Ameiica 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 thinlv these statements 

 and figm-es 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 — remo^dng it from its posi- 

 tion as a half-way house, and placing it in the category of an out- 

 side station. 



191. The plan of om- work takes us necessarily into the air, for 

 The scope of these the sea dcrives from the winds some of the most 

 researches. striking featurcs in its physical geography ; and from 



the air all of its meteorology. Without a knowledge of the ^^ands, 

 we can neither miderstand the navigation of the ocean, nor make 

 om-selves intelligently acquainted with the great highv^ays across 

 it. As with the land, so with, the sea ; some parts of it are as 

 untravelled and as unknown as the gTeat 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 

 Till.) is an immense waste of waters. None of the commercial 

 thoroughfares of the ocean lead through it ; only the adventurous 

 whaleman finds his vray there now and then in pm'suit of his game ; 

 but for all the purposes of science and navigation, it is a vast 

 unknown region. Now, Vv^re 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 supphes the wind vrith food for the rain which these busy 

 messengers convey away from the ocean to " the springs in the 

 valleys Vv'hich run among the hills." To the philosopher, the 

 places which supply the vapours are as suggestive and as interest- 

 ing for the instruction they afford, as the places are upon which 

 the vapours are showered do^Ti. Therefore, as he who studies the 

 physical geography of the land is expected to make himself ac- 

 quainted with the regions of precipitation, so he who looks into 

 the physical geography of the sea should search for the regions of 



