160 Observations on the Cause of the Spouting 



Sell//, on the circumstance that the quantity of spouting water 

 is not diminished, when several wells have been bored quite 

 close to each other, whlbh induces him to think that the pres- 

 sure of the air must there be the cause of motion. 



The workings of mine» and quarries have shown, that, in 

 certain kinds of ground, the waters spread out into veins, 

 stripes, brooks, and even sometimes torrents, running through 

 the cracks, fissures, and natural perforations of the interior of 

 the rocky strata * ; while, in other kinds of ground, they form 

 sheets or expanses of various extent, in beds of sand, earth or 

 permeable stones, — and the moment the upper stratum is per- 

 forated, they rise and spring out with greater or less rapidity, 

 until they have attained the level from which they come. 



Such is the basis of our theory of the spouting of subterra- 

 nean waters : it is merely the result of what we daily see in the 

 Avorkings of mines. It is the application of the theory oi Jets 

 cTeau and syphons. It is, in fine, so simple, and so natural, 

 that it is hardly possible to offer one more satisfactory. 



The thermal waters which rise to the surface from the inte- 

 rior of primitive formations, owe their springing to the dis- 

 engagement of compressed gases which react upon the surface 

 of these waters, in the same manner as vapour acts upon the 

 water in the Eolypile, 



Brought over,... 82 feet. 

 At this depth of 82 feet water was found ; but as it was not 

 abundant, the boring was continued. 



Black slate, 1C8 



250 

 At the depth of 250 feet there was a plentiful disengagement 

 of hydrogen gas in the black slate, 32 



282 

 At the depth of 282 feet the water sprung up to the height of four feet 

 above the surface of the ground. 



• The quarries of Paris, and, in general, all large quarries, present fre- 

 quent examples of vestiges of subterranean brooks or currents now drj'-, 

 which must formerly have traversed the limestone mass at different heights, 

 by means of the fissures and tortuous cavities which intersect it in all 

 directions. 



