THE DRIFT OF THE SEA. 



245 



been deprived of this heat in the extra-tropical or polar regions, 

 return again toward the equator ; it being assumed that the drift 

 or flow is from the poles when the temperature of the surface 

 water is helow, and from the equatorial regions when it is above 

 that due the latitude. Therefore, in a mere diagram, as this plate 

 is, the numerous eddies and local currents which are found at sea 

 are disregarded. 



529. Of all the currents in the sea, the Gulf Stream is the best 

 defined ; its Hmits, especially those of the left bank, are always 

 well marked, and, as a rule, those of the right bank, as high as the 

 parallel of the thirty-fifth degree of latitude, are quite distinct, be- 

 ing often visible to the eye. The Gulf Stream shifts its channel 

 {§ 53), but nevertheless its banks are often very distinct. As I 

 write these remarks, the abstract log of the ship Herculean (Will- 

 iam M. Chamberlain), from Callao to Hampton Roads, in May, 

 1854, is received. On the eleventh of that month, being in latitude 

 33° 39^ north, longitude 74° 56'' west (about one hundred and thirty 

 miles east of Cape Fear), he remarks : 



" Moderate breezes, smooth sea, and fine weather. At ten 

 o'clock fifty minutes, entered into the southern (right) edge of the 

 Stream, and in eight minutes the water rose six degrees ; the edge 

 of the stream w^as visible, as far as the eye could see, by the great 

 rippling and large quantities of Gulf weed — more '■ weed' than I 

 ever saw before, and I have been many times along this route in 

 the last twenty years.'" 



530. In this diagram, therefore, I have thought it useless to at- 

 tempt a delineation of any of those currents, as the Rennell Cur- 

 rent of the North Atlantic, the " connecting current" of the South, 

 '' Mentor's Counter Drift," Rossel's Drift of the South Pacific, &c., 

 which run now this way, now that, and which are frequently not 

 felt by navigators at all. 



531. In overhauling the log-books for data for this chart, I have 

 followed vessels with the water thermometer to and fro across the 

 seas, and taken the registrations of it exclusively for my guide, 

 without regard to the reported set of the currents. When, in any 

 latitude, the temperature of the water has appeared too high or too 

 low^ for that latitude, the inference has been that such water w^as 

 warmed or cooled, as the case may be, in other latitudes, and that 

 it has been conveyed to the place where found through the great 



