480 
CURRENTS AND WHALING. 
and rheumatism, and the health of Europeans is less affected than at 
other seasons, because the climate is then less dissimilar than usual to 
their own. 
“ The comparative unhealthiness of Prince’s Island to that of St. 
Thomas’s, and of both to Anno Bon, as the residence of Europeans, 
has been frequently and particularly noticed by Portuguese authori¬ 
ties, and is universally recognised at Prince’s Island and at St. 
Thomas’s. It may be a sufficient explanation to remark, that Anno 
Bon is always surrounded by the Equatorial Current; Prince’s always 
by the Guinea Current; and that the position of St. Thomas’s is 
intermediate, and its climate is occasionally influenced by both. In 
tropical climates, a very few degrees of temperature constitute an 
essential difference in the feelings of the natives, and in the health of 
Europeans.” 
In taking a general view of the facts which have been stated, it 
will appear that, towards the western sides of the North and South 
Atlantic, of the North and South Pacific, and of the Indian Oceans, 
streams of heated water, making their way from low to high latitudes, 
prevail. These in the two northern oceans become easterly, setting 
towards the opposite continents, causing, beyond all question, the 
comparatively equable and elevated temperature that is found on their 
western coasts, and which so peculiarly distinguishes the climate of 
the British Islands. To keep up the equilibrium of the ocean, the 
body of water thus thrown from the equator towards the poles, must, 
after being cooled and rendered more dense in the higher latitudes, 
return towards the equator; and the mode in which at first sight it 
might be expected to do this is by currents wholly submarine. But 
the influence of the returning water is felt at the surface also, forming 
the surface polar streams, of which we have spoken. Those which 
come from the great body of ocean in the southern hemisphere are 
directed upon the projecting points of the continents and great islands. 
Cape Horn, the Cape of Good Hope, Cape Leeuwin, &c., where as a 
general rule, they are divided into two branches. The easternmost of 
these meet the equatorial streams, of which I have spoken, whose 
direction they change, modifying or checking their progress towards 
the poles, and forming what I have termed the nuclei. In the North 
Atlantic, we have seen that a part at least of the North Polar Stream 
divides upon Cape Finisterre, passes into the Bay of Biscay, assuming 
the form of a surface current allied to an eddy, called the Rennell 
Current, while its main branch pursues its southern course along the 
coast of Portugal, and finally again becomes wholly submarine. 
On the western side of the North Atlantic, in the higher latitudes, 
