[ 457 ] 
what has already been obferved is fufficient to fhew 
us that the warmer the water is, the more it dilates the 
ivory (though we faw that the mercury rofe in the 
hygrometer after having funk for a moment). From 
hence, I fancy, may be drawn this general confe- 
quence, already indeed forefeen, namely, that in an 
equal a&ting quantity , the warmer the humor is, the 
more it feparates the particles of thofe bodies which 
it pervades. . 
107. I fay, in an equal affling quantity ; and this is : 
one of the objects which will probably furnifh us 
with a variety of moft ufeful knowledge, at the 
fame time that it is moft likely to give the greateft 
exercife to the genius and attention of natural phi- 
lofophers. The forementioned experiment proves, 
that the warmer the water is, the more it dilatates the 
ivory pipe of the hygrometer, and the fame thing I* 
make no doubt happens with the difcrete humor. 
On the other hand, the evaporation being cer- 
tainly greater in fummer than in winter, -there muft 
of courfe be more vapours in the air in the firft ; 
of thefe feafons than in the latter. Thefe then, as 
it appears, are the two circumftances moft likely to > 
make the hygrometer fall in fummer; a greater de- • 
gr.ee of humor in the air, and an encreale of heat. * 
And yet I have already experienced that the mean 
height of the hygrometer is greater in fummer than in 
the other feafons. 1 found my firft hygrometer, , 
which was made in winter, too fhort in thefum- 
mef; but it would be' of a fufficient length now ’ 
that we are in autumn. The mean height of the ' 
four new ones is already (the beginning of- Novem- 
ber) ) 
