40 [Assembly 



1848, the mean heat of the last half of July was ^72. 6 degs. ; in 

 1854, was 76.9 degs.; in 1856, was 76 degs.; and in 1857, was 

 73.3 degs. ; hot for half a month. In 1848, the mean of the first 

 half of August, was 74 degs.; in 1853, was 76 degs. ; and in 

 1858, was 73.5 degs. ; this is hot too. I see, too, that the range 

 above 90 degs. was more in some of them than in 1863. The 

 great heat of the last August, was owing to the continuance of 

 a high temperature, rarely above 90 or 92 degs. through day and 

 night, and not to so high heat through the middle of the day. 



Temperature of last half of July and first half of August for 



several years. 



Last half First half of 



of July. August. 



Years. Mean. Mean. 



1851 72.58 ._ 69.25 



1852 70.64 66.20 



1853 69.33 76.11 



1854 76.90 70.02 



1855 73.77 71.02 



1856 76.04 69.80 



1857 73.35 71.09 



1858 69.67 73.47 



1859 ._. 69.54 ._ 72.31 



1860 67.75 67.93 



1861 69.27 68.29 



1862 _ 69.31 72.89 



1863 68.96 74.98 



Mean 71.25 Mean 71.02 



For the 26 years the heat of the last half of July is greater 

 than that of the first half. The first half of August is warmer 

 than the last half; but it is cooler than the last half of July. 

 The last half of July, 1856, was 76.04, and had in it one 95 

 degs., one 94 degs., one 93 degs., one 91 degs., and twice 90 degs.; 

 much higher than the " heated period." 



The last half of July, 1854, was 76.9 degs.; twice 96 degs., 

 once 92 degs., and once 90 degs. ; much hotter than this hot 

 period. 



Still there was something peculiar in the state of the atmos- 

 phere in this " heated period," which was so oppressive at the 

 north, and farther south than the District of Columbia. 



