[ 504 ] 



to fhi? laft, confequently nearly correfponciing with the bvgrome- 

 trical degree LXXXIV, the degree found in the ferond obfeiva- 

 ti'-n ; ther fore you may conclude, that this degree oT apparent 

 drvnefs did not proceed from any decreafe of vapours in the air, but 

 folely from the increaje of heat. 



But, 2do. If in the fecond obfervation the hygrometer had been 

 at LXXXVI, then it is plain that it ftands about two hygrome- 

 trical degrees higher than five degrees of heat would have brought 

 it to, and confequently that there was an increafe of as much va- 

 pour as would raifc the hygrometer about two degrees. 



3tio. If, in the fecond obfervation, the hygrometer had been 

 found at LXXX, it is plain that this is four hygrometrical degrees 

 lower than the accefTion of five degrees of heat would have funk 

 it to ; therefore there was a decreafe of as much vapour as would 

 lower the hygrometer four degrees if the firft temperature had re- 

 mained. 



Again, to difcover the efFeds of cold and diftinguifh them from 

 the eifedls of a real accejfton of vapour the fame cafe will ferve, 

 only inferting the obfervations, (for 1^,399 degrees of cold would 

 bring XCVIII to C) Suppofe then the firfl obfervation to be 

 LXXXIV nearly, and that the air being cooled five degrees of Reau- 

 mur. 



