CURRENTS AND WHALING. 509 



only 74°, the extremes being from 73£° to 74i°, a part of the passage 

 being, moreover, on the very edge of the two currents, and within 

 sight of St. Thomas's. The vicinity of the Equatorial Current, there- 

 fore, when the sun is in the northern signs, cannot fail materially to 

 influence the temperature of the island, (particularly as the wind is 

 always from the south,) and thus to affect its climate. Situated on 

 the equator, St. Thomas's has naturally two cold seasons, or winters, 

 in the year, the sun being equally distant in June and in December ; 

 but in June, July, and August, is superadded the influence of the 

 surface water of the ocean, several degrees colder than in November, 

 December, and January ; rendering the months of June, July, and 

 August, pre-eminently the winter of St. Thomas's; in which the 

 natives complain of colds and rheumatism, and the health of Euro- 

 peans 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 cli- 

 mate 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, 



vol. v. 128 



