iDid Spouting Faiintuins. 213 



tity of water that passes under any of the bridges of this capi- 

 tal), has about 10,'30T,000 acres of superficies. The water 

 which descends into this basin, if it did not evaporate, nor pe- 

 netrate into the soil, and if it were quite horizontal, would sup- 

 ply it at the end of the year with a covering of water about 

 twenty inches deep. It is easy to discover that this mass would 

 consist in round numbers of about .677,000,000,000 (six hun- 

 dred and seventy-seven thousand millions) cubic feet of water. 

 Now, the average discharge of the Seine at the Bridge de la 

 Revolution is 7,537 cubic feet per second. 



652,740,000 day. 



234,585,140,000 annum* 



Which 4ast number is to the 677,000,000,000 which annually 

 fell into the basin of the river nearly as one to three. Thus the 

 volume of water which annually passes under the bridges of 

 Paris is not much above a third of that which descends in rain 

 into the basin of the Seine. Two thirds then of this rain either 

 reascends into the atmosphere in the way of evaporation, or sup- 

 ports vegetation and the life of animals, or finds its way into the 

 sea by subterranean communications. -|- 



' Cubic Feet 



per Second. 



' The smallest quantity ever known to pass (in 1767 & 1803) was 2,187 

 The average quantity when the river is low, . . 3,2o7 



The average quantity when the river is in its ordinary condi- 

 tion, ....... 7,171 



The quantity during the flood of January 1802 was . 23,282 



The greatest quantity ever recorded (1615), . . 40,838 



Thus, during the great flood of 1615, the Seine sent down a volume of water 

 nearly twenty times greater than when in its lowest state during the droughts 

 of 1767 and 1803. 



t On the road to Fontainebleau, at a place called Rungis, there is an abun- 

 dant spring, the waters of which, after uniting in a subterranean canal which 

 is constructed with much care, run, crossing the aqueduct of Arcueil, into 

 the reservoir of the Chateau (TEau, at the Observatoire, whence it is distributed 

 to various parts of the capital. Lahire states that it yields about fifty inches, 

 and, according to him, " the extent of ground whence the water is derived 

 ia not sufficient to feed so great a spring, merely by the rain which falls, 

 though not a drop of it was lost." But this opinion, unaccompanied with any 

 precise calculation of the extent of the ground, and the annual quantity of 

 rain, belongs to that class of vague notions of which science can take no acr 



7 



