28 



THE POPULAR SCIENCE MONTHLY. 



Fig. 2. 





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 !!%>''^-;, 





I- 



ii 



character by the short passage through the rocks that intervene be- 

 tween them and the fault ; and hence they insist that the theory of 

 percolation is untenable. There are two methods of securing the 

 mineral springs of this locality : the first is shown at Fig. 2, and con- 

 sists in excavating to an extent of 

 twenty or thirty feet square surround- 

 ing the sjDOt where indications of min- 

 eral water are observed, and extending 

 downward through the various drift- 

 formations until the underlying rock 

 is reached. As the work j)rogresses, 

 a shaft or crib is sunk in order to pre- 

 vent the sides from caving in ; and, to 

 obviate the collection of water and 

 carbonic-acid gas at the bottom of the 

 shaft, powerful steam-pumps are kept 

 in constant operation, which effectual- 

 ly drain the excavation. After reach- 

 ing the fissured crevices in the rock 

 that environ the fault, and through 

 which the water issues, a pyramidal 

 wooden hopper, about one foot square 

 at the apex, and two or three feet at 

 the base, is placed on the rock directly 

 over that portion of the crevice from 

 which the water issues most abun- 

 dantly, its position being firmly secured by packing clay tightly around 

 its exterior. As rapidly as the work of filling in the shaft progresses, 

 a wooden tube, about one foot square, is accurately adjusted to the 

 hopper, from which the water gradually rises until it reaches the out- 

 let at or near the toj:). The depth at which the rock is located from 

 the surface varies from fifteen to fifty-seven feet. The flow of water 

 from springs secured in this manner averages from thirty to one hun- 

 dred and twenty gallons an hour. 



The second method (see Fig. 3) consists in drilling into the rock, 

 in close proximity to the fault, until mineral water is obtained, the 

 drill in the mean time being followed by an iron pipe, which effectu- 

 ally secures the flow, prevents the access of fresh water, and protects 

 the rock through which the drill passes from the combined disintegrat- 



incT action of both the water and carbonic-acid 



gas. 



Most of the 



springs secured in this manner are spouting in character ; their flow is 

 not, however, continuous, but spasmodic or intermittent. This pecul- 

 iarity is undoubtedly due to a pocket or cavity in the rock, as repre- 

 sented in Fig. 3. A is the tube leading from the pocket to the sur- 

 face. As the water flows into the pocket from the surrounding inlets, 

 it gradually rises above the outlet, which results in the compression of 



