Sprmgs and Artificial Fountains. 275 



As to the shaft A''" which is twice as deep as the preceding, not- 

 withstanding its greater depth, and the two sheets of water which it 

 has passed (a a and a'a^) the water does not rise higher than in the 

 shafts A', A'^, A"', because these two sheets of water are both sup- 

 plied by the basin A. 



It is the same with the shaft B. Finally the shafts C^ C'', C"', 

 supplied by the irregular stream cc, which has its origin in the basin 

 C, show 1st. that the shaft C, if it was only bored to the depth of the 

 shaft C would not yield water, because the stream pursued the irreg- 

 ular course of the surface of the inferior formation and that it is ne- 

 cessary to bore deeper to reach the water at C. And 2d. that the 

 shaft C'^ descending still lower, does not yield any at this depth, 

 in consequence of the elevation of the intermediary, or transition for- 

 mation which interrupt in this part, the flowing of the stream c c, or 

 that if this shaft afforded overflowing water it would rise from the 

 sheets b h and h'b' which it had intersected, and that thus, notwith- 

 standing the great depth of this shaft, the ascending water could nev- 

 er rise above that of the two shafts B', and B''. 



The plate II. represents, Hke the preceding, the section of an in- 

 termediary, or transition formation, upon strata of primordial rock, 

 but with this difference, that the strata of intermediary rock, are ele- 

 vated and inclined against the primitive, but as they descend deeper, 

 they become horizontal and are finally covered with tertiary formations, 

 or detritus {de transport) and alluvial in horizontal beds. 



There are seen in the superior regions, three basins A, B, C, and 

 at the junction of the transition and the detritus, a fourth basin Dj 

 finally, the four basins have the subterranean outlets AA, BB, CC,. 

 DD, between the impermeable strata. 



The shaft D', bored through the alluvial depositions, reaching only 

 the sheet of water DD, will not yield water above the surface of the 

 earth, as the basin D, from which this sheet proceeds, being in a region 

 of country of an inferior level to that where this shaft is bored. 



But the shafts C', B', and A' yield waters above the surface of 

 the earth, to a height equal to that of the basins C, B, A, in which 

 they have their origin. 



OBSERVATIONS. 



These two plates present only the application of all the figures of 

 jets d'eau and syphons, in our Treatise d'Hydrodynamique et d'Hy- 

 drauUque, to the over-flowing of water in shafts, formed by boring. 



