Dr Forry on the Climate of the United States. 93 



Platte and Missouri, 24°. 47 and 75°.82 ; thus shewing that 

 the disparity in the mean temperature of winter and summer, 

 on the same parallel of latitude, and on the same isothermal 

 line (that of Foi-t AVolcott being 50°.61, and that of Council 

 Bluffs, 51°.02), is 14°. 80 greater in an excessive th&n in a uni- 

 form climate. 



As those who first observed the climatic difference between 

 western Europe and eastern North America, were natives 

 of the former, they of course regarded the climate of their 

 own country as constituting the rule, and that of America 

 as the exception ; while some, even now, as, for instance, 

 Lyell, as already quoted, make Europe the exception to the 

 general rule. But when these facts came to be genei'alized, 

 it was discovered that the eastern coasts of both continents 

 have a lower annual temperature and more contrasted 

 seasons than the w^estern in corresponding latitudes. These 

 results find a satisfactory explanation in physical causes ; 

 thus demonstrating the harmony of the laws of climate 

 throughout the globe. 



Did space allow, it would be easy to shew that the rationale 

 of all these laws finds a ready explanation in the phenomena 

 of the polar and equatorial cun-ents, in connection with cer- 

 tain local causes. Suffice it to refer to a single explanation. 

 Tlie wands without the tropics have a prevailing direction 

 from the west, — a fact which affords a solution of the pro- 

 blem that in extra-tropical latitudes, countries lying to the 

 eastAvard of seas or other great bodies of water, have milder 

 climates than those situated on the eastern portions of a 

 continent. That this westerly breeze prevails with consider- 

 able regularity, is apparent from the following observations 

 made by John Hamilton, during twenty-six voyages between 

 Philadelphia and Liverpool, from 1798 to 1817, shewing that 

 the winds were more than half the time from the west. 

 Thus, out of 2029 days, the winds prevailed 



From northward, . . . 208 days. 

 ... southwai'd, 

 ... eastward, 

 ... westward, 

 Variable, 



