CURRENTS AND WHALING. 
471 
that the line continued to hang vertical during the whole three hours 
that the observation continued. He justly ascribes this occurrence to 
the motion of the whole body of water to the north with an equal 
velocity. The set towards the coast in the more southern portion of 
the stream is shown by the frequent wrecks on the coast of Chili, and 
the difficulty which vessels leaving Valparaiso to double Cape Horn 
experience 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 pheno¬ 
mena of currents occur in this neighbourhood, and particularly around 
the more southern ones, that are obviously due to this cause, 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 westward, and 
merges in the Equatorial Stream of the Pacific. 
The temperature of the water 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 
