360 INDIAN SUMMER. 



vapour. But as the earth becomes gradually 

 cooler on the approach of winter, by radiating 

 more caloric than it receives from the sun, the 

 air over it is also cooled down ; the transparent 

 vapour is slightly condensed into a fine hazy 

 mist, that reflects and refracts the solar rays in 

 such a manner as to produce the most rich and 

 softened lustre of the bluish purple and golden 

 air; which continues until there is a change of 

 wind sometimes, for three weeks in succession. 

 As the Indian summer is generally a dry season, 

 and as the mountains and prairies are frequently 

 on fire during such weather, the hazy appear- 

 ance of the atmosphere has been attributed by 

 many persons to the vapour of burning sub- 

 stances diffused through the air. But this cause 

 is altogether too limited in its operation to ac- 

 count for the prevalence of Indian summer 

 throughout the greater part of the American 

 continent ; and often many hundred miles from 

 burning prairies. The conflagrations that occur 

 during this season are local and transitory ; 

 while the gradual cooling down of the earth, 

 during the prevalence of warm southerly breezes, 

 is all sufficient to account for the phenomenon. 

 The same cause produces in England the most 

 dense and gloomy fogs, during the same beautiful 

 season in America. This is readily understood, 

 when we reflect that England is surrounded by 

 the ocean, that its atmosphere is much nearer 



