Br Forry on the Climate of the United States. 77 



40°*75. Between the two posts on the ocean and the two 

 far in the intei'lor, the difference between the mean tempera- 

 ture of summer and winter presents a disparity of from 15" 

 to 17° ; and as respects Fort Trumbull and West Point, 

 which are precisely on the same latitude, the difference be- 

 tween these two opposite seasons, notwithstanding the latter 

 is not more than fifty miles from the ocean, is 8°* 19 less at 

 the former post. As regards the diflference between the 

 mean temperature of the warmest and coldest months, these 

 laws find confirmation in every instance. So remarkable is 

 the influence of large bodies of water in modifying the range 

 of the thermometer, that although Fort Brady, at the Sault 

 St Marie, Michigan, is nearly 7° north of Fort Mifflin, near 

 Philadelphia, and notwithstanding the mean annual tempera- 

 ture is more than 14° less, yet the contrast, in the seasons of 

 winter and summer, is not so gi'eat at the former as at the 

 latter. Fort Columbus, in the harbour of New York, offers, 

 in some respects, an exception to the laws just developed; the 

 range of the thermometer being greater than at some points 

 farther north. As these results, which are based on nine 

 years' observations, made on an island fi'ee from any agency 

 which large towns may exercise, are doubtless correct, some 

 causes of a local nature must exist to produce this effect. It 

 is more than probable that this locality, in consequence of 

 the configuration of the coast, does not lie in the direction of 

 the most prevalent ocean-winds, and that hence its tempera- 

 ture is but partially modified. 



The climate of Fort Snelling, which is the most excessive 

 among all the military posts in the United States, resembles 

 that of Moscow in Russia, as regards the extremes of the 

 seasons, notwithstanding the latter is 11° farther north ; but 

 at Moscow the mean temperatui'e both of winter and summer 

 is lower — that of winter being as 10°-78 to 15°'95, and that 

 of summer as 67°-10 to 72°-75. At Edinburgh, Scotland, in 

 the same latitude as Moscow, the difference between the 

 mean temperature of winter and summer is, on the other 

 hand, not one-third as great, being only 17°'90 ; and even at 

 North Cape, on the island of Maggcroe, in latitude 71", which 

 is the most northern point of Europe, this diflerence between 



