Hygrometry . 393 
That Angle determination, from its great confequences not 
yet generally attended to, would be fufficient to fix the cele- 
brity of its author, as I have already expreffed many times in 
other works. 
6 y. But with refped to a different conclufion from the fame 
experiments, no lefs important to natural philofophy, I have 
alio faid, that M. be Saussure’s hygrometer may have milled 
him. We have feen, that the manometer indicated, by an 
indubitable fymptom, the maximum of evaporation ; for here 
the immediate caufe is clearly known, namely, the quantity of 
elafiic fluids ; and it is evident, that the quickfilver muft afcend 
in the inftrumentin proportion to that quantity x and flop when 
it ceafes to increafe. But it is not the fame as to the indica- 
tions of the hygrometer in refpedt of moiflure : M. de Saus- 
sure found himfelf that they were far from proportional to 
the intenfities of their caufe ; and in the laft ftage of his ex- 
periments, though thefe indications did not vary much by the 
different maxima of evaporation , they however varied in the 
fpace of 1 or 2 degrees . But as thofe fmall differences on the 
point where the hygrometer flopped in different experiments, did 
not follow apparently any law conformable to the temperature , 
M. de Saussure confidered them as fmall anomalies , una- 
voidable in hygrofcopic fuhftances, and of little confequence 
on a fcale of ioo degrees % therefore, laying afide that circum- 
ftance, he could have no doubt, that, in every temperature , 
the maximum of evaporation in a clofe fpace was fynonymous 
with the maximum of moiflure in that fpace; while, from my 
experiments, thefe two fuppofed identical expreffions may differ 
I, and fometimes of the real fcale of moiflure , which is the 
cafe in the temperature of only 75 0 or 8o°. 
Vol. LXXXL F f f 
68. Let 
