FORMATION OF SPRINGS. 45 



to open springs by sinking wells, or by piercing 

 the earth, with the boring rod. If the boring 

 auger breaks into a reservoir of water, the contents 

 of the latter rise up the shaft, and flow out, often 

 gushing up as a fountain, if the reservoir below 

 derives its supplies from higher levels. Such are 

 the Artesian Springs or Spring Wells, which owe 

 their origin to the very same principles as do 

 artificial fountains. Geology teaches us the cir- 

 cumstances under which we may form conclusions 

 with the greatest probability of truth as to the 

 existence of subterraneous veins of water; and 

 therefore the experiment of boring for water, if 

 conducted by an experienced geologist, cannot be 

 considered as a speculation of mere hazard. 



One condition, that is universally requisite for 

 the formation of artesian spring-wells, is, that 

 there should he at some depth below the sur- 

 face a stratum having an inclination to the hori- 

 zon, and traversed with fissures (a feature which 

 belongs especially to the limestone rocks). An- 

 other is that this stratum must, at some higher 

 level, crop out to the surface or at least only be 

 covered with some light soil, which allows the 

 water to trickle through : and over its lower parts 

 must he some stratum through which water cannot 

 pass, as for instance a thick layer of stiff clay; 

 so that the rain water draining in from above may 

 fill the hollows, and may run down the slope of 



