CLIMATOLOGY. 



317 



fying, destroying, or enhancing the effect of others, as small 

 undulatory movements which encounter and intersect each 

 other are known to do. Such is the spirit of the method 

 by which I persuade myself it will some day be possible to 

 combine by empirical laws, numerically expressed, vast series 

 of apparently insulated facts, and to manifest their reciprocal 

 dependence. 



The trade winds (which are easterly winds blowing 

 within the tropics), are the occasion of the west and west- 

 south-west winds which prevail in both the temperate 

 zones. These are of course land winds to eastern coasts, 

 and sea winds to western coasts. The surface of the ocean 

 not being susceptible of being cooled in the same degree as 

 that of the land, by reason of the mass of its waters, and the 

 tendency of its particles to sink immediately they are cooled 

 and to be replaced by cooler from below, it follows that, 

 where easterly winds prevail, western coasts should be warmer 

 than eastern coasts, except a counteraction exists in oceanic 

 currents. Cook's young companion on his second voyage of 

 circumnavigation, the ingenious George Porster, to whom I 

 em indebted for the lively interest which prompted me to 

 undertake distant travels, was the first who distinctly called 

 attention to the difference of temperature between the 

 eastern and western coasts of the two continents; and 

 to the similarity of temperature, in the mean latitudes, of 

 the west coast of America and the west coast of Europe. ( 391 ) 

 Even in more northern latitudes, exact observations shew 

 a striking difference between the mean annual temperatures 

 of the east and the west coasts of America. Nain, in 

 Labrador, in 57 10' N. lat., has a mean annual temperature 

 of _3.8 Cent. (25.2 Fah.), or 6.8 Fah. below the freezing 



