l/t^etahle Statich. 8 1 
the tranfverfe cut of the branch, was co- 
vered with innumerable little hemifpheres of 
air, and many air bubbles iffucd out of 
the fap veflels, which air did in part fill 
the tube e r, as the water was drawn cut of 
it j fo that the height of the mercury could 
only be proportionable to the excefs of the 
quantity of water drawn off, above the quan- 
tity of air which iffued out of the wood. 
And if the quantity of air, which iffued 
from the wood into the tube, had been equal 
to the quantity of water imbibed, then the 
mercury would not rife at all ; bccaufc there 
would be no room for it in the tube. 
But if 9 parrs in 12 of the water be im- 
bibed by the branch, and in the mean time 
but 3 fuch parts of air iffue into the tube, 
then the mercury muft needsrife near6inchcs, 
and fo propoftionably in different cafes. 
I obferved in this, and moft of the follow- 
ing experiments of this fort, that the mer- 
cury rofe higheft, when the fun was very 
clear and warm j and towards evening i^ 
would fubfide 3 or 4- inches, and rife again 
the next day as it grew warm, but fcldom 
to the fame height it did at firft. For I 
have always found the fap vcffels grow every 
G day. 
