274 Springs and Artificial Fountains. 



In fact natural overflowing fountains are always formed, when there 

 exists a superior basin, from which the water can flow, through nat- 

 ural channels ; it is seen : 



1st. That a shaft, formed by boring, is really but an artificial issue 

 differing only from these natural conduits, by the regularity of its 

 sides and direction, which tend to facilitate the ascent of the water ; 



2d. That the success of boring will be much more certain, when 

 attempted in a region composed of impermeable strata, separated by 

 beds of sand or gravel, through which infiltrate the effusions of a 

 volume of subterranean water, or of superior basins. 



And 3d that there are fewer chances of success, in compact and en- 

 tirely impermeable formations, which afford only streams or subterra- 

 nean currents, which escape through the crevices, fissures or irregular 

 perforations of beds, or strata of stone and consequently render- 

 ing it uncertain what place to select for commencing boring. 



Plate I. represents the geological section of a region, in which the 

 primitive formation is covered in one part, by transition, or intermedi- 

 ary formations, partly compact, and in part crystallized, disposed in 

 inclined strata with crevices and fissures, which traverse tliese stra- 

 ta in different directions ; and in another part with secondary deposi- 

 tions, and by horizontal alluvial beds, which rest against the interme- 

 diary and transition formations, and cover them deeply. 



The superior parts of the region present at different heights, basins, 

 lakes, or rivers. A, B, C, sometimes placed upon the line of juxta-po- 

 sition of the alluvial and transition formations, and sometimes on the 

 last. 



When the waters of these basins, lakes, or rivers find crevices, 

 fissures or drains, below their beds, they lose themselves, or infiltrate 

 by these issues and are subterraneously diffused, and form the sheets 

 aa, a'a\ hh, h'h', in the sand or gravel, upon the clay or impermea- 

 ble formations, or constituting irregular streams, as presented by the 

 line of superposition cc, of transported earths upon those of deposi- 

 tion, — " sediment.'''' 



The bored shafts a', a" and a'", descend to the sheet of water 

 aa, supplied by the effusions of the basin a, yielding in the shaft a' 

 the ascending water, which reaches to the surface of the earth, while 

 in the shaft a" it spouts above, and in the shaft a'" it remains below 

 the surface, rising in each of these perforations, at a height propor- 

 tioned to that of the level of the basin A. 



