The Paris Sewage Irrigation at Gennevilliers. 
Ill 
efficacy of the agricultural system for thoroughly solving the 
sewage problem, I will now examine the economical principles 
upon which that system is based, and describe, with their re- 
sults, the processes resorted to by the Paris Sewage Commission. 
This will form, I hope, an interesting chapter in the history of 
sewage. An account of what has been done in this instance 
may be useful to other civic corporations, who are contemplating 
the application of the same system to the disposal of the sewage 
of their localities ; and it is with that view, although I may fall 
short of my purpose, that I have attempted the task of writing 
this paper. 
It may be said of the application of town-sewage to agricul- 
ture, that the thought of it arose more from the necessity of 
getting rid of a pestilential nuisance than from any want of fer- 
tilising matter felt by agricultural husbandry, or from a well- 
defined conviction that any great advantage would accrue there- 
from to the public weal, by promoting an extra growth of crops, 
or improving any large extent of unproductive land. 
The truth is, that so far as agriculture is generally concerned, 
the application of sewage is of slight interest; not, indeed, in 
respect to its effects on land, which, it must be admitted, are 
very remarkable, but from the fact that the available supply 
is so limited, that the extent of land that might be benefited is 
comparatively very narrow. 
For instance, the whole of the land which the sewage of the 
city of Paris, however large its bulk may be, could effectually 
irrigate, does not exceed 12,000 acres, the produce of which, 
enhanced though it might be under the influence of such an 
irrigation, would barely provide for the food of one-fifth of the 
city s population. 
But if the sewage question is but of small import to agricul- 
ture, it possesses a paramount interest in respect to the health of 
towns, and lies heavy in the responsibilities of civic corporations. 
The necessity of disposing of the offals of human agglomera- 
tions is a charge, the whole burden of which must exclusively 
fall upon the cities themselves. Agriculture is willing enough to 
bear a helping hand in laying out her fields for the purification 
of town-sewage, and is even thankful for the benefit it will un- 
doubtedly derive from it ; but the costly process through which 
the supply is made available to agriculture must naturally be 
left to the charge of municipalities, the boon to husbandry not 
being adequate to so large an outlay. 
The great merit of the application of sewage, so far as agri- 
culture is concerned, consists, then, in its simplicity. The fer- 
tilising stream must be brought within the immediate reach of 
the land, at a level that will allow its flow and self-distribution 
