and Spouting Fountains. 225 



gulfed in the immense caverns of a mountain ; nor the rivers 

 which come out of such caverns, as happens in the cavern Gua- 

 charo. I wisl), on the other hand, to designate those streams of 

 water, which are, as it were, substituted for certain beds, for 

 certain deposits of the original strata, and of which they now 

 occupy the place. 



Some surprise may perhaps be experienced when I mention, 

 first of all, that under Paris and its environs, these subterranean 

 water-courses exist. We shall now, however, prove the truth of 

 this remark. 



It happened some time ago that some workmen perforated the 

 ground near to the barrier of Fountainebleau, in an establish- 

 ment which is known under the name of the Brewery of the 

 Maison Blanche. As usually happens in these instances, the 

 progress was slow and the work tedious ; but, in a moment, it 

 happened that the instrument with which they were boring the 

 earth, suddenly escaped from their hands, and they saw it fall 

 rapidly upwards of twenty feet. If the transverse handle had 

 not been at the lop of the first joint of the borer, the instrument 

 might have disappeared altogether ; but as the hole previously 

 dug was narrow, it was caught at the depth already mentioned. 

 When the workmen endeavoured to draw up the borer, it then 

 appeared that it was as if suspended, — that its lower end did not 

 rest upon any solid support ; in short, that a strong current be- 

 low was carrying it to one side, and causing it to oscillate. The 

 rapid ascent of the waters of this deep stream prevented the exa- 

 minaiion from being carried further. 



At die Port Saint Ouen, the Messrs Flachat recognised that 

 the third of the five sheets of water which their operations brought 

 under review, flowed in a cavity nearly twenty inches deep. 

 In truth, the borer sunk down suddenly in it more than a foot ; 

 and the current must have been very strong indeed, since it 

 impressed the whole borer with a very sensible oscillatory mo- 

 tion. This double result, viz. the existence of the current, and 

 its strength, may akso with certainty be deduced from another 

 curious fact. When the point of the boring instrument, filled 

 with debris of the rocks which it had been penetrating lower 

 down, came, in drawing it up, to the spot where this third sheet 

 of water was, it was not necessary to raise it any further; for in 



