INFLUENCE OF THE GULF STREAM UPON CLIMATES. 51 



ribbean Sea are the caldrons ; the Gulf Stream is the conducting 

 pipe. From the Grand Banks of Newfoundland to the shores of 

 Europe is the basement — the hot-air chamber — in which this pipe 

 is flared out so as to present a large cooling surface. Here the 

 circulation of the atmosphere is arranged by nature ; and it is such 

 that the warmth thus conveyed into this warm-air chamber of 

 mid-ocean is taken up by the genial west winds, and dispensed, in 

 the most benign manner, throughout Great Britain and the west 

 of Europe. 



63. The maximum temperature of the water-heated air-cham- 

 ber of the Observatory is about 90°. The maximum temperature 

 of the Gulf Stream is 86°, or about 9° above the ocean tempera- 

 ture due the latitude. Increasing its latitude 10°, it loses but 2° 

 of temperature ; and, after having run three thousand miles to- 

 ward the north, it still preserves, even in winter, the heat of sum- 

 mer. With this temperature, it crosses the 40th degree of north 

 latitude, and there, overflowing its liquid banks, it spreads itself 

 out for thousands of square leagues over the cold waters around, 

 and covers the ocean with a mantle of warmth that serves so much 

 to mitigate in Europe the rigors of winter. Moving now more 

 slowly, but dispensing its genial influences more freely, it finally 

 meets the British Islands. By these it is divided (Plate IX.), 

 one part going into the polar basin ^ Spitzbergen, the other en- 

 tering the Bay of Biscay, but each with a warmth considerably 

 above the ocean temperature. Such an immense volume of heated 

 water can not fail to carry with it beyond the seas a mild and moist 

 atmosphere. And this it is which so much softens climate there. 



64. We know not, exc^ept approximately in one or two places, 

 what the depth or the under temperature of tlie Gulf Stream may 

 be ; but assuming the temperature and velocity at the depth of 

 two hundred fathoms to be those of the surface, and taking the 

 well-known difference between the capacity of air and of water for 

 specific heat as the argument, a simple calculation will show that 

 the quantity of heat discharged over the Atlantic from the waters 

 of the Gulf Stream in a winter's day would be sufficient to raise 

 the whole column of atmosphere that rests upon France and the 

 British Islands from the freezing point to summer heat. 



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