422 ARTESIAN WELLS. 



It appears that there are extensive districts in various parts 

 of Europe, where, under certain conditions of geological 

 structure, and at certain levels, artificial fountains will rise 

 to the surface of strata which throw out no natural springs,* 



Notices scientifiques par M. Arago. Annuaire, pour f'An. 1835. 



Von Bruckmann xlber Artesische Brunnen. Heilbronn am Neckar, 1833, 



* The Diagrams in PI. 69. Figs. 1 and 2. are constructed to illustrate the 

 causes of the rise of water in natural, or artificial springs, within basin- 

 shaped strata that are intersected by the side of Valleys, or traversed by 

 Faults, 



Supposing a Basin (PI, 69 Fig. 1.) composed of Permeable strata, E, F, G. 

 alternating with impermeable strata, H, I, K. L. to have the margin of all 

 these strata continuous in all directions at one uniformly horizontal level, A, 

 B, the water which falls in rain upon the extremities of the strata E, F, G, 

 would accumulate within them, and fill all their interstices with water up to 

 the line A, B; and if a Pipe were passed down through the upper, into either 

 of the lower strata, at any point within the circumference of this basin, the 

 •water would rise within it to the horizontal line A, B, which represents the 

 general level of the margin of the Basin. A disposition so regular never exists 

 in nature, the extremities or outcrops of each stratum are usually at different 

 levels, (Fig. 1, a. c. e. g.) In such cases the line a. b. represents the water 

 level within the stratum G; below this line, water would be permanently 

 present in G ; it could never rise above it, being relieved by springs that 

 would overflow at a. The line c, d. represents the level above which the 

 water could never rise in the stratum F ; and the line e, f, represents the 

 highest water level within the stratum E. The discharge of all rain-waters 

 that percolated the strata, E, F, G, thus being effected by overflowing at 

 e. c. a. 



If common wells were perforated from the surface, i. k, 1. into the strata 

 G, F, E, the water would rise within them only to the horizontal lines a b, 

 c d, e f. 



The upper porous stratum C, also, would be permanently loaded with water 

 below the horizontal line, g, h, and permanently dry above it. 



The theoretical section, PI. 69. fig. 2. represents a portion of a basin inter- 

 sected by the fault H, L, filled with matter impermeable to water. Sup- 

 posing the lower extremities of the inclined and permeable strata N, O, P, 

 Q, R, to be intersected by the fault or dike H, L, the rain-water which 

 enters the uncovered portion of these strata between the impermeable clay 

 beds, A, B, C, D, E, would accumulate in the permeable strata up to the 

 horizontal lines, AA", BB", CC", DD", EE". If an Artesian well was 

 perforated into each of these strata to A', B', C, D', E', through the clay 

 beds A, B, C, D, E, the water from these beds would rise within a pipe ascend- 

 ing from the perforations of the levels A", B", C", D", E", 



