Dr. Forry on the Climate of the United States, Sfc. 39 



paper on Isothermal Lines and the Distribution of Heat over the 

 Globe ; but these various relations, owing of course to the pau- 

 city of his data, are not characterized by ranch precision. 



The isothermal Hue of 41°, which, according to this philoso- 

 pher, passes through the Bay of St. George, in Newfoundland, 

 in the latitude 48°, if correctly ascertained, sinks as it penetrates 

 towards the interior of the continent ; for at Hancock Barracks, 

 Maine, in latitude 46° 10', at a distance of one hundred and fifty 

 miles from the Atlantic, the mean annual temperature is 41°-21, 

 and at Fort Brady, at the outlet of Lake Superior, in latitude 46° 

 39', it is 41°-39 ; and proceeding to the western coast of Amer- 

 ica, we find that at Fort Vancouver, Oregon Territory, in latitude 

 45° 37', the mean temperature, like similar parallels in western 

 Europe, is as high as 5i°-75, 



As the region of the United States, however, exhibits very di- 

 verse systems of climate even on the same parallels, such com- 

 parative tables, as for instance the difference of the seasons from 

 the equator to the polar circle, can present only the most general 

 laws. For example, it shows that on the isothermal line of 41°, 

 the mean temperature of winter is 14°, and that of summer 

 660.2Q — ^ result obtained from observations made in lat. 48°, on 

 the Bay of St. George, Newfoundland. Now, according to the 

 " Army Meteorological Register," this isothermal line is again 

 found in the comparatively equalized climate of Fort Brady, at 

 the outlet of Lake Superior, in lat. 46° 39', where the mean 

 temperature of winter is as high as 21°-07, while that of summer 

 is only 63°- 18. Again, the table shov/s that on the isothermal 

 line of 50°, the mean temperature of winter is 30° -20, and that 

 of summer 71°-50; but this too gives only a partial view, as at 

 Fort Wolcott, Rhode Island, the former is 32° -51 and the latter 

 69°-06, and at Council Bluffs, near the junction of the Platte 

 and Missouri, 24°-47 and 75° 82 ; thus showing 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 Fort 

 Wolcott being 50°-61, and that of Council Bluffs 51°02,) is 

 14° 80 greater in an excessive than in a uniform 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 coun- 

 try as constituting the rule, and that of America as the excep- 



