Vegetable Static k$. 57 
water, which is conveyed away, by fprings 
and rivers, from thofe hills, that we need 
not have recourfe, for fupplies, to the great 
Ahjfs-> whole 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 longeftand 
greateft rivers take their rife. 
Experiment XX. 
I provided me fix Thermometers , whofe 
fie ms were of different lengths, viz. from 
1 8 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 ve- 
getation ceafes, the watry vehicle beginning 
then to condenfe and be fixed $ tho’ many 
trees, and fome plants, as grafs, mofs, <&c. 
do furvive it; yet they do not vegetate at 
that time. 
The greateft degree of heat, which I at 
firft marked on my Thermometer s> 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 
