426 DEAIISTAGE BY BOEING. 



they strike a stratum of gravel, tlirougli whicli tlie water readily 

 passes off. 



This practice has been extensively employed at Paris, not merely 

 for carrying off ordinary surface-water, but for the discharge of 

 offensive and deleterious fluids from chemical and manufacturing 

 •estabHshments. A well of this sort received, in the winter of 

 1832-'33, twenty thousand gallons per day of the foul water from 

 a starch factory, and the same process was largely used in other 

 factories. The apprehension of injury to common and artesian 

 wells and springs led to an investigation on this subject by Girard 

 and Parent Duchatelet, in the latter year. The report of these 

 gentlemen, pubhshed in the Annates des Ponts et Chaussees for 

 1833, second haK-year, is full of curious and instructive facts re- 

 specting the position and distribution of the subterranean waters 

 under and near Paris ; but it must suffice to say that the report 

 came to the conclusion that, in consequence of the absolute im- 

 mobility of these waters, and the relatively small quantity of 

 noxious fluid to be conveyed to them, there was no danger of the 

 diffusion of such fluid if discharged into them. This result will 

 not surprise those who know that, in another work, Duchatelet 

 maintains analogous opinions as to the effect of the discharge of 

 the city sewers into the Seine or the waters of that river. The 

 quantity of matter dehvered by them he holds to be so nearly 

 inflnitesimal, as compared with the volmne of water of the river, 

 that it can not possibly affect it to a sensible degree, and there- 

 fore can not render the Seine water unfit for drinking.* 



Meteorological Effects of Draining. 



The draining of lakes diminishes the water-surface of the soil, 

 and consequently, in many cases, the evaporation from it, as well 

 as the refrigeration which attends all evaporation.f On the other 



* Coste found, in his experiments on pisciculture, that the fermentation, 

 which takes place in the water of the Seine in consequence of the discharge 

 of the drains into the river, destroyed a large proportion of the eggs of fish 

 in his breeding basins. Analysis of Seine water by Boussingault in 1855, de- 

 tected a considerable quantity of ammonia. 



f The relative evaporating action of earth and water is a very complicated 

 problem, and the results of observation on the subject are conflicting. Schil- 

 •bler found that at Geneva the evaporation from bare loose earth, in the months 



