Sewage- Farminrj. 
405 
number of persons can bo restored tlirou2:b tlie soil, that only 
our present ig^noranco prevents our securing crops which will 
pay ior such an application, but that vegetation is unable bene- 
ficially to appropriate a greater amount. With such differences 
of opinion, enough land should at any rate be secured ; and, for 
reasons which I shall presently enter into, I think the farmer 
should not estimate more than 40 or 50 persons to the acre, and 
possibly less than either of those numbers. 
The quantity of water supplied to the population will deter- 
mine approximately the strength and amount of sewage on 
which he has to depend, assuming that the storm-water is 
excluded from the sewers, and that they do not receive land- 
drainage to any extent. It is almost impossible for the farmer 
to deal satisfactorily with sewage which will be infinitely 
increased in quantity (at the same time that it is diluted in 
strength) when he least requires an addition in such a shape. 
Nevertheless, so little attention has been paid to this important 
point, that at Bedford, where the supply of water to the inha- 
bitants reaches but 150,000 gallons daily, the average quantity 
of sewage which reaches the pumping-station is no less than 
600,000 gallons. At Warwick the sewage amounts to double 
the quantity of water supplied to the population ; and at Dover, 
with 1,000,000 gallons of water-supply, the discharge from the 
sewers amounts to 3,500,000 daily. Where each inhabitant is 
supplied with 30 gallons of water per diem, a total of 50 tons per 
head per annum will be available for sewerage purposes ; and, as 
this is a fair and liberal but at the same time not excessive 
supply, we may take it as a basis for our calculations on the sub- 
ject. This quantity, where 50 persons contribute to each acre, 
will give a supply of 2500 tons of sewage per acre per annum, 
equivalent to a vertical depth of 25 inches, which, in dry districts, 
will fully equal that of the rainfall ; while taking lOO persons 
as contributors, no less than 5000 tons of sewage, containing 
ammonia of the value of upwards of 40Z. per acre, will have to 
be disposed of, and, I need hardly add, in a great degree wasted. 
But unsatisfactory as is this prodigality, far greater quantities 
than even the latter are lavished at present upon some sewage- 
cultivated land. When Mr. J. C. Morton published his ' Agri- 
cultural Experience of 800,000 tons of North London Sewage ' 
in 1867, he estimated that at Barking 100 tons of sewage would 
be required to produce one ton of rye-grass over and above the 
natural and unassisted growth of the land. What have been 
the facts? In 1870, a year of exceptional drought and heat, no 
less than 314 tons of sewage were used for every ton of grass cut ; 
while in one instance the prodigious quantity of 450 tons was 
applied for each ton of grass produced ! That is to say, 11,500 
