500 CURRENTS AND WHALING. 



ence in obtaining a sufficient offing. This stream, like the others we 

 have spoken of, varies in breadth and strength at different seasons. 



We experienced the set of this stream in a decided manner ; for the 

 amount of our drifting current between Cape Horn and Valparaiso, 

 was two hundred and fifty-four miles, in a direction north-by-east. 



The change in direction from northeast to north takes place about 

 the latitude 37° S., or in the neighbourhood of the island of Mocha. 



In our passage from Valparaiso to Callao, we found the waters of a 

 low temperature ; but the general effect of current, amounting to one 

 hundred and seventy-one miles, was in a direction nearly due west. 

 The surface Polar Stream therefore seems to be deflected by the bight 

 formed by the coasts of Chili and Peru, but after passing this it again 

 receives its direction to the north. 



Off Callao this stream is confined to narrow limits, but is still 

 readily distinguishable by its low temperature, and the drift of the 

 ship to the northwest; the breadth was estimated at one hundred 

 miles. 



The Gallipagos Islands oppose an obstacle to this stream, and 

 phenomena of currents occur in this neighbourhood, and particularly 

 around the more southern ones, that are obviously due to this course, 

 and which the isothermal lines on the chart clearly indicate. By 

 these islands also the stream is divided into two branches, one of 

 which is felt as far to the north as Panama; the other is thrown west- 

 ward, and merges in the Equatorial Stream of the Pacific. 



The temperature of the w T ater around these islands is low, as might 

 be expected from the Polar Current reaching them ; and thus may be 

 explained the remarkable fact, that, although under the equator, no 

 coral is found there, because the water is below the temperature at 

 which, according to Mr. Dana, the animals that form the coral reefs 

 can live, or at least become numerous ; this will hold good with all the 

 coasts washed by polar currents. 



Between Callao and Tahiti, after crossing the Polar Stream, we 

 experienced little current. Among the islands of the Paumotu Group 

 none whatever was perceived, and our whole drift was no more than 

 seventeen miles in a direction N., 57° E. 



On approaching these islands, the change in the surface temperature 

 was of the same description as we afterwards experienced in other 

 similar cases, namely, an increase. We thus have a fact to aid in 

 proving that the opinion generally entertained, that on coming into 



