70 Dr. Heberden's account of the heat of July, 1825 ; 
rays of the sun, or from any object heated by it. I have 
been the more particular in giving this account, because it is 
often difficult, especially in great, or rapid changes of tem- 
perature, to get observations made with sufficient attention 
to avoid the neighbourhood of buildings, or other objects, 
which may considerably affect the thermometer, and give an 
appearance of heat sometimes greater, sometimes less than 
the truth. 
In order to ascertain the greatest heat, the thermometer 
was repeatedly examined at short intervals during the hottest 
period of the day. The highest degrees indicated, under the 
circumstances I have detailed, were as follows : 
July 15. 
- 
- 
92° wind S. W. 
17. 
- 
- 
90 ° 'j 
18. 
- 
- 
96° iwind E. 
19. 
- 
- 
95 ° * 
The 16th is not set down, because, though it was a hot 
day, yet being several degrees cooler than the day preceding, 
it was not thought worth while to examine the thermometer 
with the same attention. 
There is some reason to believe that an unusual degree of 
heat was felt about the same time, not only in most parts of 
Europe, but also in America. 
The only instance of heat, that I am aware of having been 
noticed in England equal to this, was in July 1808 ; on the 
13th of which month the thermometer is stated, in the 
Meteorological Journal of the Royal Society, to have risen to 
93^- . On the 12th it had stood at 90°, and on the 14th it 
was 91 0 ; the wind at the same time varying from east to 
