192 Sewage and Sewerage. | April, 
sells for about 87. per acre; it is used chiefly for stall-feeding dairy 
cows. The expense of laying out the surface for irrigation was 
stated to be from 62. to 100. per acre, of which the Local Board 
paid 4/.; the cost of the rough filtration is nearly defrayed by the 
sale of the deposit, which fetches about 1s. 6d. per load.” 
To this we may add that the success of Croydon has been 
rivalled at Carlisle and Edinburgh ; and that in all three of these 
cases, the soil on to which the sewage has been discharged has been 
a more or less light loam, or even, as at Craigentinny, barren 
sand ;* and, finally, that from none of these places has any evi- 
dence as yet been gathered as to the applicability of sewage to root 
or grain crops. The history or rather the natural history of 
Croydon furnishes a curious proof of the thoroughness of the 
purifying to which sewage is subjected by irrigation. At p. 51 of 
the Report just quoted we read :—“ Before the present arrangements 
were in force, the Croydon board had to meet numerous law-suits, 
on account of the pollution of the river by the sewage; but so 
efficiently is the sewage now purified, that those having the right 
of fishing in the river have found it worth while to fix gratings to 
prevent the fish going up the main outfall from the sewage irrigated 
land.” We believe, however, that, though putrid sewage is poisonous 
under all circumstances, alike to man and beast, perfectly fresh 
sewage is, even when wholly unfiltered, far from bemg destructive 
of fish and of other (especially invertebrate) forms of aquatic life. 
The pike haunted the mouths of Agrippa’s main drains; and a bold 
explorer may readily satisfy himself of the identity in this respect of 
the habits of modern English and of ancient Roman fish. Fish 
thus fed were considered in the time of Juvenal, and may be con- 
sidered also in ours, as exceedingly proper food for the parasites or 
hangers-on or henchmen of the rich man; but fat and well-liking 
though such fish are, we should be sorry to see them set before any 
other class of the community. They pick out, it is true, from the 
solid matter of sewage, fragments and particles which would other- 
wise have to undergo a long series of dismemberments into simpler 
and simpler compounds, till some kindly vegetable should deign to 
re-compound them, and they build up these débris at once imto 
their own substance, but this substance or flesh of theirs, we submit, 
can scarcely seem attractive when its history is considered, and we 
believe besides that persons who, being superior to prejudices, will 
venture upon it, will find other than sentimental reasons for abjuring 
its use. 
It is the solids of sewage which, though containing perhaps but 
a sixth or aseventh part of its valuable elements, make it so difficult 
to deal with. They cannot be allowed to spread or smear them- 
selves over the vegetable growths, to which either as grass in the 
* «Third Report,’ Appendix, p. 199. 
