Vegetable Statich. 57 



of water, which is conveyed away, by fprings 

 and rivers, from thofe hills, that we need 

 not have recourfe, for fupplies, to the great 

 Abyfs, whofe furface, at high water, is fur- 

 mounted fome hundreds of feet by ordi- 

 nary hills, and fome thoufands of feet by 

 thofe vaft hills from whence the longeft 

 and greateft rivers take their rife. See vol. II. 



A 2 57- 



Experiment XX. 



I provided me fix Thermometers, whofe 

 items were of different lengths, viz. from 

 18 inches to 4 feet. I graduated them all by 

 one proportional fcale, beginning from the 

 freezing point* which may well be fixed as 

 the utmoft boundary of vegetation on the fide 

 of cold, where the work of vegetation ceafes, 

 the watry vehicle beginning then to condenfe 

 and be fixed -, tho' many trees, and fome plants 

 as grafs, mofs, &c. do furvive it 5 yet they 

 do not vegetate at that time. 



The greateft degree of heat, which I at 

 firft marked on my Thermometers, was equal 

 to that of water, when heated to the great- 

 eft degree that I could bear my hand in it, 

 without ftirring it about. But finding by 

 experience, that plants can endure, with- 

 out 



