236 Dr. Forry on the Climate of the United States, S^c. 



mate of the United States, and its Endemic Influences," might be 

 traced out much farther. At Council Bluffs, the extreme of tem- 

 perature in summer is also much greater than at Fort Trumbull, 

 the mean maximum of the former being 104^, and of the latter 

 87°, and consequently the average annual range stands respec- 

 tively as 120° to 78°. In addition to these facts, it may be ob- 

 served that so far as elevation is concerned, that of the lakes be- 

 ing 600 feet and that of Albany only 130 feet above the sea, the 

 advantage of the comparison is, at first view, on the side of the 

 latter ; but this gradual elevation, it has been shown, exerts no 

 perceptible influence. 



Does the climate of our northioestern frontier resemble that of 

 the Eastern States on their first settlement 1 



This question, it is true, has already been decided in the nega- 

 tive ; but as changes of climate in the New World also are alleg- 

 ed by Jefl"erson, Volney, Rush, and Williams, to have supervened, 

 it may be well to make some inquiry into its truth. It is deemed 

 mmecessary to quote here the loose, vague, and general state- 

 ments of these writers, who thus assert that, on comparing the 

 results of recent observations on our frontier with the best authen- 

 ticated accounts we have of the climate of the Eastern states in 

 their early settlement, a close similitude is found. The winters, 

 it is said, have grown less cold and the summers less warm — con- 

 sequences which are ascribed to the clearing of the forest and 

 the cultivation of the soil. That the climate of the great lakes 

 resembles that of the sea-coast is very apparent ; but that the re- 

 gion intermediate or the one beyond, ever maintained such a re- 

 lation, is an assumption contrary to the laws of nature. 



Dense forests and all growing vegetables, doubtless tend consid- 

 erably to diminish the temperature of summer, by affording evap- 

 oration from the surface of their leaves, and preventing the calo- 

 rific rays from reaching the ground. It is a fact equally well 

 known, that snow lies longer in forests than on plains, because, 

 in the former locality, it is less exposed to the action of the sun ; 

 and hence, the winters, in former years, may have been longer 

 and more uniform. As the clearing away of the forest causes the 

 waters to evaporate and the soil to become dry, some increase in 

 the mean summer temperature, diametrically contrary to the opin- 

 ion of Jefferson, Lyell, and others, necessarily follows. It is re- 

 marked by Umfreville that, at Hudson's Bay, the ground in open 



