bo METEOROLOGY- 



to the same class of phenomena, and for which tlie same explanation 

 must be given. Seasons of comparative rest in the atmosphere are of 

 frequent occurrence, and the sky is scarcely ever free from matter, what- 

 ever that may be, which destroys its transparency. Instead, therefore, 

 of confining ourselves to the single phenomenon, whose name stands at 

 the head of this article, it is thought best to bring all the most import- 

 ant cases of a similar character together, and then inquire how far they 

 may all be referable to the same great atmospheric laws for their exist- 

 ence. 



Passing by the numerous minor cases, happening generally at inter- 

 vals of about two weeks, and, because of their freciuency, striking no 

 one, except perhaps the meteorologist, as in any respect remarkable, we 

 may direct our attention to four periods during the year, at which, with 

 considerable regularity, are to be witnessed the great distinguishing char- 

 acteristics of the "Indian Summer." 



The Jirst occurs, with but little variation as to time, at about the 

 close of October, or the beginning of November. It scarcely extends 

 as far as the 12th or 13th of the latter month. This is the season to 

 which the name of "Indian Summer" has been appropriated. In its 

 duration it is not perfectly uniform, sometimes continuing for two or 

 three weeks, and at others only as many days. During tlie Autumn of 

 1S43, it continued only for five days, viz. from the 2Sth of October to 

 the 2nd of November. Neither is it uniform in its intensity, it being, 

 during some years, scarcely distinguishable from the rest of the seasons. 

 Thus the case just cited was so faintly characterized, as to have led 

 many persons to suppose that during that year there was no Indian 

 Summer. And though it lasted about the usual length of time during 

 the Autumn of 1844, viz. from the 2nd to the 12th of November inclu- 

 sive, it was interrupted near its commencement by a storm continuing 

 three days and a half, and was so faintly marked, that for every thing, 

 except that it occurred at the proper time of the year, it scarcely deserv- 

 ed the name Indian Summer as much as a great part of the month of 

 September did. From this it would appear that the Indian Sunnner of 

 October and November is not so peculiar as is generally supposed. 



A second period of similar atmosplieric condition, occurs at about the 

 middle or close of Aj)ril. This is, sometimes, extremely well marked ; 

 so much so as to arrest the attention of even tlic casual observer. A- 

 mong numerous cases which have occurred, that of 1833 may be cited 

 as very remarkable For about tliree weeks, commencing in April and 

 continuing until the 9lli of iMay, the atmosphere was darkened by what 

 had the ajipcurance uf smoke, which was al'terwards enforced by real 



