ATMOSPHEROLOGY.— TEMPERATURE. 355 



of April (New Style,) furnishes a mean tempera- 

 ture, which does not materially differ from that of 

 the whole year * ; — that a month, the middle of 

 which falls on the 24th of July is the warmest of 

 the year ; or that in the average of centuries, the 

 24th of July is prohahly the warmest day in the 

 whole year ; — that the 22d-23d of January is the 

 coldest of the whole year; — that the 19th-20th of 

 Octo])er, and the 27th-28th of April, are each, on 

 a long average, of the same mean temperature as 

 that of the year ; — that the difference hetween the 

 mean temperature of the year and that of January, 

 is nearly the same, though probably not quite so 

 great, as the difference between the mean of the 

 year and that of July f ; — and that in high northern 

 latitudes, the progressive increase of temperature 

 from January to July, and the decrease from July 



z 2 



* From the fifty years observations at Stockholm, wherein the 

 mean teraperatm*eof every five days throughout theyeai-isgiven, 

 the mean of the penthemeron, which bears the mean tempera- 

 ture of the year, is the 27th-28th of April, which is later by one 

 day only, than the middle-day of April (O. S.) And the mean 

 of thirty days, or fifteen preceding and fifteen following the 

 27th-28th of April, differs from the mean of the penthemeron 

 by only a small fraction of a degree ; consequently, a month, 

 of which the 27th-28th of April is the middle, may be con- 

 sidered as affording a temperature corresponding with that of 

 the year. The 19th of October, taken as a mean of five days, 

 likewise affords the mean temperature of the year. — (See An- 

 nals of Phil. vol. i. p. 114., & 266.) 



+ The difference between the mean temperature of the j^ear 

 and that of January, in Stockholm, is one-fourteenth part less 



