[ 414 ] 
cup exactly, no longer filled it. After a few hour?, 
I perceived that the internal furface grew wet, and by 
means of a magnifying glafs, found it covered with a 
very fine dew. This dew did not encreafe by the 
veflel remaining any longer in the water ; the eva- 
poration being doubtlefs equal to the tranfudation • 
and the capacity of the veflel, which encreafed till the 
appearance of the dew, feemed afterwards at a fhnd. 
26. This tranfudation puzzled me a little ; it 
fhewed me that the water would get into my hygro- 
meter, which at firfl: appeared an inconvenience. I 
foon, however, found an advantage in it. The wa- 
ter, after having foaked through the ivory, would 
immediately pufh back the mercury, which having 
by degrees funk in the tube, during the penetration 
of the water through the pores of the ivory, muft 
thus rife again. Hence I might expedl a maximum 
for the fall of the mercury, very eafy to be deter- 
mined. As for the water introduced into the ivory 
veflel, I was in hopes that it would go back as foon 
as the outfide of the cup fhould be dry. 
27. Having thus ascertained that ivory was very 
eafily affeded by the impreflions of the humor, it ftill 
was neceflary to know, whether the variations of the 
one would always equally anfwer to thofe of the 
other. Having accordingly taken my fmall cup out 
of the water, and expofed it to the air, I foon found 
that its capacity diminifhed, but that even after fe- 
veral days it did not return to its former ftate. This 
again puzzled me ; but I fufpe&ed that the external 
preflure of the tool upon the ivory might fomewhatr 
have comprefled it, and that the water having re- 
ftored the ivory fibres to their original pitch, the 
abfalute 
