[ 3^8 ] 



NW. moderately ftrong. The ufual ftate of the hygrometer was 

 from LXXV. to XC. and often flill higher. 



The greateft lofs by evaporation which I ever obferved in one hour, 

 from my atmedometer, was forty-five grains, its furface was 

 25,23 fquare inches, and it contained 23,13 cubic inches of water, 

 barometer 30,00 inches, thermometer (which I always keep 

 fhaded from the fun) 68°, 5, hygrometer LXXIX. initial heat of 

 the water 66*^, final 64°, wind E. moderately ftrong ; and the 

 fmalleft lofs in one hour was two grains, but frequently I could 

 perceive no lofs during the firft hour, and fometimes fome lofs 

 during the firft, fcarce any during the fecond, the water being 

 frozen. 



Thus on the ift of March 1785, barometer 30,15, thermo- 

 meter from .23° to 25°, wind N. initial heat of the water 32^, 

 final 32°, but frozen hard, it loft five grains the firft hour and 

 one on the fecond hour, while frozen. The quantity of water 

 in a cubic foot of air I found by fulphuric acid to be 5,4 grains : 

 1 had then no hygrometer, but by Sauflure's table it could not 

 be far from faturation. But I have frequently obferved a lofs of 

 from fix to eight grains during the firft hour, thermometer 26*^, 

 and even fix grains, when frozen, when the atmedometer was 

 fully expofed to the open air. But during foggy and calm days 



there 



