122 The Pai-is Sewage Irrigation at Gennevilliers. 
villiers from the two outlets of Clichy and St. Ouen may be 
computed at 44,000 tons from each, daily ; but only one-four!th 
of that quantity was used in 1874. 
The following Table shows the progressive rate of the 
quantities used since the commencement : — 
Number of Acres 
irrigated. 
Quantities used. 
3869 
16 
650,000 Tons. 
1870 
55 
810,000 „ 
1871 
War and Commune. 
1872 
128 
1,500,000 „ 
1873 
221 
7,200,000 „ 
1874 
289 
8,000,000 „ 
1875 
314 
The sewage, as already stated, is pumped up at Clichy to the 
level of the Genevilliers' embankment by means of powerful 
pumping-engines of 150-horse power. From the higher level 
to which the sewage is pumped up, pipes, 4 feet in diameter, 
bring it along the Clichy Bridge to the plain. The sewage of 
St. Ouen, commanding a higher level, simply flows by its own 
gravitation through a main 2 miles in length, and directed to 
the extreme end of the peninsula. Both streams are then united 
in an open channel, built in bricks and cement, more than a 
mile in length, and 7 feet wide, running along the Genne- 
villiers and Asnieres embankment. From that main, subsidiary 
canals of various widths and lengths, complete the distributive 
network. 
Before we examine the agricultural results which have hitherto 
been obtained from the direct application of the Parjs sewage 
to the land, it may be well to examine its chemical composition, 
in order to render possible a comparison with the sewage of 
English towns, and especially that of London. 
From the fact I have alrcadv stated, that the solid excre- 
mentitious matter is not allowed to pass into the sewers, it may 
be inferred at once that a notable difference may be expected 
between the sewage of both cities, especially as regards its 
manuring value. 
riiis difference exists to a remarkable degree between the 
Clichy and the St. Denis sewage-waters. At the latter place, 
where the great northern main discharges its contents, the refuse 
of the \^oTu\y jioudrctte manufactory falls into the sewer, and the 
numerous manure-works of that neighbourhood send their con- 
tjngent to the sewage ; and the consequence is that a much 
