168 HISTORY OF 



earth eyery-where covered with water, evapora* 

 tion alone would be sufficient to carry off two feet 

 nine inches of it in a year : and yet we very 

 well know, that scarcely nineteen inches of rain 

 water falls in that time; so that evaporation 

 would carry off a much greater quantity than is 

 ever known to descend. The small quantity of 

 rain water that falls is therefore but barely suffi- 

 cient for the purposes of vegetation. Two leaves 

 of a fig-tree have been found, by experiment, 

 to imbibe from the earth, in five hours and a 

 half, two ounces of water. This implies the 

 great quantity of fluid that must be exhausted 

 in the maintenance of one single plant. Add 

 to this, that the waters of the river Rungis will, 

 by calculation, rise to fifty inches ; and the 

 whole country from whence they are supplied 

 never receives fifty inches in the year by rain. 

 Besides this, there are many salt springs, which 

 are known to proceed immediately from the sea, 

 and are subject to its flux and reflux. In short, 

 wherever we dig beneath the surface of the 

 earth, except in a very few instances, water is to 

 be found ; and it is by this subterraneous water 

 that springs and rivers, nay, a great part of vege- 

 tation itself, is supported. It is this subterraneous 

 water, which is raised into steam by the internal 

 heat of the earth, that feeds plants. It is this 

 subterraneous water that distils through its in- 

 terstices ; and there cooling, forms fountains. 

 It is this that, by the addition of rains, is increas- 

 ed into rivers, and pours plenty over the whole 

 earth. 



