92 Dr Forry on the Climate of the United States. 



where the mean temperature of the year is that of the coast 

 of Brittany, the scorching heats of summer are greater than 

 at Cairo, and the winters are as rigorous as at Upsal." 



The difference of climate between western Europe and 

 eastern North America, was long since determined by Hum- 

 boldt, in his paper on Isothermal Lines, and the Distribution of 

 Heat over the Globe ; but these various relations, owing of 

 course to the paucity of his data, are not characterised by 

 much precision. 



The isothermal line of 41°, which, according to this philo- 

 sopher, passes through the Bay of St George, in Newfound- 

 land, in the latitude 48', if correctly ascertained, sinks as it 

 penetrates towards the interior of the continent ; for at Han- 

 cock Barraclcs, Maine, in latitude 46° 10', at a distance of 

 one hundred and fifty miles from the Atlantic, the mean an- 

 nual temperature is 41^.21, and at Fort Brady, at the outlet 

 of Lake Superior, in latitude 46' 39', it is 41°. 39; and pro- 

 ceeding to the western coast of America, 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 51°. 75. 



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

 diverse systems of climate, even on the same parallels, such 

 comparative tables, as, for instance, the difference of tlie sea- 

 sons from the equator to the polar circle, can present only 

 the most general laws. For example, it shews that on the 

 isothermal line of 41°, the mean temperature of winter is 

 14°, and that of summer 66^.20 — a result obtained from ob- 

 servations made in lat. 48°, on the Bay of St George, New- 

 foundland. Now, according to the "Army Meteorological 

 Register," this isothermal line is again found in the compa- 

 ratively 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 

 C3°.18. Again, the table shews that on the isothermal line 

 of 50°, the mean temperature of Avinter is 30°. 20, and that 

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

 at Fort Wolcott, Rhode Island, tlie former is 32 "51, and the < 

 latter 69'.06, and at Council Bluffs, near the junction of the 



