102 VJLJiWS OF NATURE. 



the summer temperature of America is lower under equal de- 

 <A' latitude than that of Kurope. The climate of St. Pc- 

 tersburgh (lat. 59 56'), or to speak more correctly, the mean 

 annual temperature of that city, is found on the eastern coast 

 of America, in lat. 47 30', or 12 30' more to the south; and 

 in like manner we find the climate of Kdnigf berg (lat. 54 43') 

 at 1 lalif'ax in lat. 44 39'. Toulouse (lat. 43 U 30') corresponds 

 in its thermic relations to Washington. 



It is very hazardous to attempt to obtain any general 

 results respecting the distribution of heat in the United States 

 of North America, since there are three regions to be dis- 

 tinguished 1, the region of the Atlantic States, east of the 

 Alleghanys; 2, the Western States, in the wide basin 

 between the Alleghanys and the Rocky Mountains, watered 

 by the Mississippi, the Ohio, the Arkansas, and the Missouri ; 

 and 3, the elevated plains between the Rocky Mountains and 

 the Coast Range of New California, through which the 

 Oregon or Columbia river wends its course. Since the com- 

 mendable establishment by John Culhoun of uninterrupted 

 observations of temperature, made on a uniform plan, at 

 thirty-five military stations, and reduced to diurnal, mensal, 

 and annual means, we have attained more correct climatic 

 views than were generally held in the time of Jefferson, 

 Barton, and Volney. These meteorological stations extend 

 from the point of Florida and Thompson's Island (West Key), 

 lat. 24 33', to the Council Bluffs on the Missouri ; and if wo 

 reckon Fort Vancouver (lat. 45 37'), among them, they in- 

 clude a space extending over forty degrees of longitude. 



It cannot be affirmed that on the whole the second region 

 has a higher mean annual temperature than the first, or 

 Atlantic. The further advance towards the north of cer- 

 tain plants on the western side of the Alleghanys, depends 

 partly on the nature of those plants and partly on the difK i- 

 cnt distribution through the seasons of the year of the same 

 annual amount of heat. The broad valley of the Mississippi 

 enjoys, at its northern extremity, the warming influence of 

 the Canadian lakes, and at llie south, that of the Mexican 

 (mil-Stream. These live lakes (Lakes Superior, Michigan, Hu- 

 ron, Klie, and Ontario,) cover an area of 92,000 square miles. 

 Tin- climate is so much milder and more uniform in the 

 vicinity of the lakes, that at Niagara, for instance (in 43 15 



