the Distribution of Heat over the Globe. 89 



pressure amounts to 302 inches, while between Iceland and 

 Spitzbergen it is only 29*6, a lower mean pressure than is found 

 in any other place on the northern hemisphere. There must con- 

 sequently, he concludes, be a general tendency in the air to flow 

 from the former to the latter place along the earth's surface. 

 But the air in moving from the lower to the higher latitudes 

 tends to take a north-easterly direction, and in this case will 

 pass over our island in its course. But it so happens that this 

 region of high pressure is situated in the very path of the south- 

 eastern branch of the Gulf-stream. Consequently the winds 

 blowing from this region of maximum pressure will carry directly 

 to Britain the heat of the Gulf-stream. 



It is essential to the heating of our island, as well as the south- 

 ern portion of Europe, that a very large proportion of the waters 

 of the Gulf-stream should spread over the surface of the Atlantic 

 and never pass up into the arctic regions, as we shall presently see. 



But even according to Mr. Findlay's own theory, it is to the 

 south-west wind, heated by the warm waters of the Atlantic, that 

 we are indebted for the high temperature of our climate. But he 

 seems to be under the impression that the Atlantic would be 

 able to supply the necessary heat independently of the Gulf- 

 stream. This, I presume, is the fundamental error of all those 

 who doubt the efficiency of the stream. It is a mistake, how- 

 ever, into which one is very apt to fall who does not adopt the 

 more rigid method of determining heat-results in absolute mea- 

 sure. When we apply this method, we find that the Atlantic 

 without the aid of such a current as the Gulf- stream would be 

 wholly unable to supply the necessary amount of heat to the 

 south-west winds. 



The quantity of heat conveyed by the Gulf-stream, as we have 

 seen, is equal to all the heat received from the sun by 3,121,870 

 square miles at the equator. Mr. Findlay, however, as has been 

 stated, thinks that I have doubled the actual volume of the 

 stream. Assuming that I have done so, the amount of heat 

 carried by the stream would still be equal to all the heat re- 

 ceived from the sun by 1,560,935 square miles at the equator. 

 The mean annual quantity of heat received from the sun by the 

 temperate regions per unit surface is to that received by the 

 equator as 9'83 to 12*. Consequently the quantity of heat 

 conveyed by the stream, taking Mr Findlay's estimate of its 

 volume, is equal to all the heat received from the sun by2,062,960 

 square miles of the temperate regions. The total area of the 

 Atlantic from the latitude of the Straits of Florida, 200 miles 

 north of the tropic of Cancer, up to the Arctic Circle, including 

 also the German Ocean, is about 8,500,000 square miles. In 

 * See Smithsonian Contributions to Knowledge, vol. ix. 



