Half-a-dozen English Sewage Farms. 407 
That roads should receive constant and unlntermitting atten- 
tion ; and that the employment of the labourers should be on a 
systematic plan by which each man should be made responsible 
for the care of a certain length of road — by which a spirit of 
emulation would be created amongst the men, and a check 
kept, without the necessity of such constant supervision as it is 
impossible for the surveyor in charge of a long length of roads 
to bestow. 
XV. — Half-a-dozen English Sewage Farms. 
By John Chalmees Morton. 
The agricultural value of town sewage has been frequently 
discussed in this ' Journal,' and its readers have been kept 
adequately informed on the subject, as experience and research 
have from year to year thrown increasing light upon it. In 1862, 
when a Parliamentary Committee was engaged in its investiga- 
tion, and enthusiastic men there and elsewhere were urging 
extravagant estimates on public attention, a lecture by Dr. 
Voelcker, reported in vol. xxiii., pointed out the fallacy inherent 
in the merely chemical valuations on which such estimates had 
been founded, that they took no account of many considerations 
by which the value of manures is determined, quite as much as 
by their chemical composition. Professor Hoffman had, indeed, 
valued ordinary town sewage at ^d. per ton, on the same grounds 
as those by which IIZ. per ton is justified as the price of 
Peruvian guano. But upon these same grounds, ordinary farm- 
yard-dung, which could be bought for Ss. to 5s. per ton, is worth 
13s. 6t?. ! Cumbered with much material of little value, making 
the application of the really efficient elements difficult or costly, 
or unfit except at certain times to certain crops, farmyard- 
manure is not worth in practice nearly so much as, on a theory 
omitting such considerations, might be supposed. Sewage in 
like manner, which, at prices* of 56Z. per ton for its ammonia, 
and 31/. per ton for its potash, and 11. per ton for its phosphate 
of lime, might be supposed to be worth so much, may be posi- 
tively of no value whatever, except in " special cases, such as 
that of land which has in itself little or no fertilising matter, 
but is porous." Even thus early, under the guidance of one of 
the few scientific men who are also practical agriculturists, a 
sound and sober judgment on this subject was then being given 
in these pages. 
* These were the prices quoted at the date of Dr. Voolcker's paper. 
2 E 2 
