46 VITAL ACTIONS. 



connected with this subject ; * among others the fol- 

 lowing, which he relates thus : — " August 13. In the 

 very dry year 1723, I dug down 2h feet deep to the 

 root of a thriving baking pear tree, and laying bare 

 a root half an inch in diameter {fig. 7) I cut off the 

 end of the root at t, and put the remaining stump 

 (i ri) into the glass tube d r, which was an inch in 

 diameter, and eight inches long, cementing it fast at 

 r; the lower part of the tube d z was eighteen inches 

 long and a quarter of an inch diameter in bore. . . . 

 Then I turned the lower end of the tube (z) upper- 

 most, and filled it full of water, and then immediately 

 immersed the small end s into the cistern of mercury 

 at the bottom, taking away my finger which stopped 



up the end of the tube z The root imbibed 



the water with so much vigour, that in six minutes' 

 time the mercury was raised up the tube d z as high 



as z, namely, eight inches The next morning 



at eight o'clock the mercury was fallen to two inches 

 in height, and two inches at the end of the root i were 

 yet immersed in water. As the root imbibed the 

 water, innumerable air bubbles issued out at i, which 

 occupied the upper part of the tube at r as the water 

 left it." On another occasion he planted a sunflower 

 34 feet high in a garden pot, which he covered with 

 thin milled lead, cementing all the joints so that no 

 vapour could escape except through the sides of the 

 pot and through the plant itself; but providing an 

 aperture capable of being stopped, through which the 



* See Vegetable Statics, London, 17 27. 



