Dr. Forry on the Climate of the United States, fyc. 25 



chusetts, based on thirty three years' observation by Dr. Holyoke, 

 though not directly under the influence of the ocean, confirms 

 the same law, the difference between the mean temperature of 

 winter and summer being only 41°-66. At all these points, the 

 contrast in the difference of the mean temperature of the warmest 

 d the coldest month, is equally striking. The next points of 

 comparison, as lying on the same parallel, are Forts Wolcott and 

 Trumbull on the Atlantic, and Council Bluffs, Fort Armstrong, 

 and West Point, in the opposite localities. The difference be- 

 tween the mean temperature of summer and winter at Fort Wol- 

 cott, Newport, Rhode Island, is 36°-55, and at Fort Trumbull, 

 New London, Connecticut, it is 32°-56 ; while at Council Bluffs, 

 near the junction of the Platte and Missouri, it is 51°-35— at Fort 

 Armstrong, Illinois, 49°-05— and at West Point, N. Y., 40°-75. 

 Between the two posts on the ocean and the two far in the inte- 

 rior, the difference between the mean temperature 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 between these two opposite seasons, not- 

 withstanding the latter is not more than fifty miles from the ocean, 

 is8°-19 less at the former post. As regards the difference be- 

 tween 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 Philadel- 

 phia, and notwithstanding the mean annual temperature is more 

 than 14° less, yet the contrast, in the seasons of winter and sum- 

 mer, is not so great at the former as at the latter. Fort Columbus, 

 in the harbor 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 free 

 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 temperature 

 is but partially modified. 



^ Vol. xtvn, No. 1.— April-June, 1844. 4 ., . - ? . - . - i. 



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