822 THE CANADIAN NATURALIST. 



winter ; for in our frigid clime, we are glad of any shorten- 

 ing of our winter of half the year. I do not know that this 

 little mimic summer ever fails of its appearance, though in 

 some seasons it is much more brief in its duration than in 

 others. Sometimes it continues, a course of beautiful and 

 serene weather, for two or three weeks ; at others, we have 

 only as many days, hastily snatched from the sway of Boreas, 

 just to remind us of balmier times. 



C. — It is a pleasant variation, and as curious as it is 

 agreeable. Pray what is the cause of the phenomenon ? 



F. — I believe no adequate cause has yet been assigned, 

 though many conjectures have been hazarded. Some have 

 supposed the heat and mist to be evolved by the fermenta- 

 tion of those immense masses of vegetable matter, leaves of 

 trees, wild herbage, &c., which are deposited at this season, 

 over the vast forests and wildernesses of this continent. 

 But it appears to me that fermentation would take place to 

 a much gi-eater extent in the ensuing spring than in the 

 autumn, the heat of that season being likely to have a 

 greater effect on these masses, especially after their having 

 been saturated with moisture from the melting snows, which 

 have lain upon them through the winter. Others conjecture 

 that the heat and haze are caused by the fires which at this 

 season are kindled on almost every farm to consume logs, 

 brush, &c., after the drying of summer. This cause, at first 

 sight, seems very incompetent to the production of so general 

 an appearance ; but the burnings appear to be very widely 

 spread, and I have myself observed at other times, when 

 large brush fires have been burning in the neighbourhood, 

 that the smoke will be diffused and rest in the air for several 

 days, if there be no wind, causing an appearance very simi- 

 lar to the present. Still, however, I incline to think that it 

 owes its origin to natural, rather than to artificial causes. 



C. — The lepidopterous insects seem glad to avail them- 



