^ ECONOMIZING PKECIPITATION. 471 



yards, not above one-half of wliich, lie tliinks, would be lost, 

 and, of course, the other half would remain available to supply 

 the spring. I much doubt whether this expectation would be 

 realized in practice, in its whole extent ; for if Babinet is right 

 in supposing that the summer rain is wholly evaporated, the 

 winter rains, being much less in quantity, would hardly suffice to 

 keep the earth saturated and give off so large a surplus. 



The method of Palissy, though, as I have said, similar in prin- 

 ciple to that of Babinet, would be cheaper of execution, and, at 

 the same time, more efficient. He proposes the construction of 

 relatively small filtering receptacles, into which he would conduct 

 the rain falhng upon a large area of rocky hillside, or other slop- 

 ing ground not readily absorbing water. This process would, in 

 ^1 probability, be a very successful, as well as an inexpensive, 

 mode of economizing atmospheric precipitation, and of compelling 

 the rain and snow to form perennial fountains at will. 



Economizing PrecijpitaUon. 



The methods suggested by Palissy and by Babinet are of lim- 

 ited application, and designed only to supply a sufficient quantity 

 of water for the domestic use of small villages or large private 

 estabhshments. Dumas has proposed a much more extensive 

 system for collecting and retaining the whole precipitation in 

 considerable valleys, and storing it in reservoirs, whence it is to 

 be drawn for household and mechanical purposes, for irrigation, 

 and, in short, for all the uses to which the water of natural springs 

 and brooks is applicable. His plan consists in draining both sur- 

 face and subsoU, by means of conduits differing in construction 

 according to local circumstances, but in the main not unlike those 

 employed in improved agriculture, collecting the water in a cen- 

 tral channel, securing its proper filterage, checking its too rapid 

 flow by barriers at convenient points, and finally receiving the 

 whole in spacious, covered reservoirs, from which it may be dis- 

 charged in a constant flow or at intervals as convenience may 

 dictate.* 



• M. G. Dumas, La Science des Fontaines, 1867. — See article Pontinh 

 Mabshes, in Johnson's CyclopoBdia. 



