CURRENTS AND WHALING. 
463 
their approximate causes are influenced by temperature—the Gulf 
Stream being increased in mass and velocity when the temperature is 
highest, and the Labrador Stream when it is lowest; and in conformity, 
we find it a general impression that the former is broader and more 
rapid in the summer of our climate than in winter. I must however 
state, that I have been unable from my own personal observation, either 
by the thermometer or the set of the vessel, to distinguish this increase 
of the Gulf Stream in summer. Thus in my passage to England, in 
August, 1836, from the time we passed to the eastward of George’s 
Bank, in a latitude about a degree to the south of it, we experienced a 
low temperature in the water, and the vessel was retarded. We were 
therefore in the Labrador Current. 
i\.fter the squadron had crossed the Gulf Stream, we experienced 
little action from current until we reached Madeira, the whole differ¬ 
ence between our dead reckoning and the true place of the ship being 
no more than one hundred and seventy-five miles in twenty-six days. 
Before leaving this part of our subject, it may be as well to refer to 
facts familiarly known, but which did not come within the scope of our 
observations. The stream known on our coast by the epithet of Gulf, 
may often be traced upon the surface, but with diminished velocity, 
entirely across the Atlantic, throwing at some seasons the seeds and 
drift of tropical climates upon the British Islands, even as far north as 
the Shetlands. At other times, when the Gulf Stream ceases to flow, 
or is overpowered by the great Polar Current, they are carried by the 
latter to the southeastward, on the coast of Spain and Portugal, which 
current has been so disastrous by the number of vessels that have been 
wrecked on Cape Finisterre; where it divides, one branch of it passing 
around the shores of the Bay of Biscay, along the west coast of France, 
and thence crossing the English Channel, which is now well known as 
the Rennell Current; while the main Polar Stream flows southward, 
along the coast of Portugal towards Madeira, with a diminished 
velocity, as a surface current. 
That the stream which sets upon Cape Finisterre is the origin of 
the Rennell Current, the following remarks by Horsburgh clearly 
show. 
“ The current is found to set eastward, from March to November, 
particularly when westerly winds prevail; and off Cape Finisterre, and 
near the south part of the Bay of Biscay, it sets mostly along the coast 
to the eastward; and along the east coast of the bay, it sets to the 
northward, parallel to the west coast of France.” 
At Madeira and the Canary Islands the surface Polar Stream 
appears to have ceased; but by our observations on the deep-sea tempe- 
