Vtgetahle Stanch. 8 1 



the tranfvcrfc cut of the branch, was co- 

 vered with innumerable little hemifpheres cf 

 air, and many air bubbles iffued out of 

 the fap veffels, which air did in part fill 

 the tube e r, as the water was drawn cut of 

 it i 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 ; becaufe there 

 would be v no room for it in the tube. 



But if 9 parts in 1 2 of the water be irri-' 

 bibed by the branch, and in the mean time 

 but 3 fuch parts of air iffue into the tube* 

 then the mercury muft needsrife near6inches> 

 and fo proportionably 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 5 and towards evening it 

 would fubfide 3 or 4. inches, and rife again 

 the next day as it grew warm, but feldom 

 to the fame height it did at firft. for I 

 have always found the fap veffels grow every; 

 , G day ^ 



