Vegetable Siattcks . 93 
was fucked out* Probably therefore, thefe 
air bubbles, when in the fap vefiels, do flop 
the free afeent of the water, as is the cafe 
of little portions of air got between the wa- 
ter in capillary glafs tubes. 
When the mercury is raifed to its great- 
eft height, by precedent fusion with the 
mouth, (which height it reaches fometimes 
in 7 minutes, fometimes in half an hour or 
an hour) then from that time it begins to 
fall, and continues fo to do, till it is fallen 
5 or <5 inches, the height the branch would 
have drawn it to, without fucking with the 
mouth. 
But when in a very warm day, the mer- 
cury is drawn up 5 or fix inches, (without 
precedent fudion with the mouth) then it 
will ufually hold up to that height for feve- 
ral hours, viz, during the vigorous warmth 
of the fun 5 becaufc the fun is all that time 
ftrongiy exhaling moifture from the branch 
thro* the leaves, on which account it muft 
therefore imbibe water the more greedily, 
as is evident by many experiments in the 
firft chapter. 
When a branch is fixed to a glafs tube 
fet in mercury, and the mercury fubfides at 
night, it will not rife the next morning 
(as 
