which certainly is more prevalent in bottoms? or 

 rather, have not those elevated pools some unnoticed 

 recruits, which in the night time counterbalance the 

 waste of the day, without which the cattle alone 

 must soon exhaust them ? And here it will be neces- 

 sary to enter more minutely into the cause. Dr. 

 Hales, in his Vegetable Statics, advances, from ex- 

 periment, that " the moister the earth is the more 

 dew falls on it in a night : and more than a double 

 quantity of dew falls on a surface of water than there 

 does on an equal surface of moist earth." Hence we 

 see that water, by its coolness, is enabled to assimi- 

 late to itself a large quantity of moisture nightly by 

 condensation ; and that the air, when loaded with 

 fogs and vapours, and even with copious dews, can 

 alone advance a considerable and never-failing re- 

 source. Persons that are much abroad, and travel 

 early and late, such as shepherds, fishermen, &c., can 

 tell what prodigious fogs prevail in the night on 

 elevated downs, even in the hottest parts of summer; 

 and how much the surfaces of things are drenched 

 by those swimming vapours, though, to the senses, 

 all the while, little moisture seems to fall. 



Selborne, Feb. 7, 1776. 



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