1873 •] A Solution of the Sewage Problem. 59 



The abundance of crops produced on a given area has 

 been quoted in favour of the system of irrigation. The 

 finest manurial substances are possessed by the constituents 

 of sewage; but the irrigationist is so wasteful in their appli- 

 cation, that, in the majority of cases, there ensues not a 

 healthy crop, but a mass of overgrown, rank grass material, 

 of no more nutritive value than weeds ; for be it distinctly 

 remembered that this is not a question of manuring with 

 sewage when necessary, — but the compulsory application of 

 enormous quantities, in season' and out of season, till the 

 surfeited land is sick, and even then it has to take more 

 still. If this waste were prevented, by the conversion of 

 the sewage into a dry, portable, inoffensive manure, then 

 this manure might be stored until it could be employed at 

 the proper season without injurious effect ; but to dose 

 vegetation with equal quantities of manure, day by day 

 throughout the year, is an absurdity which of itself is suffi- 

 cient to condemn sewage irrigation. 



The second process, that of filtration, appears to be involved 

 in some obscurity, — that is to say, there are attached to the 

 term several meanings, of greater or less comprehension. 

 Not a little of the confusion appears due to the Rivers' 

 Pollution Commission having discussed " intermittent down- 

 ward filtration," without defining the term. We are told that 

 irrigation owes no inconsiderable amount of its success to 

 the contemporaneous effect of filtration of sewage through 

 the soil, and, confusion worse confounded, we are instructed 

 that '" irrigation involves filtration." We, however, will 

 take filtration to mean the passing of the sewage water 

 through an artificially-constructed bed of sand, charcoal, &c. 

 Filtration by itself is simply a method of disposing of sewage, 

 'not of utilising it, and therefore we hold it in no more 

 favour than the other; for we maintain that unless the 

 manurial elements are preserved for the land, as well as 

 from the river, the problem is but half solved. Filtration 

 processes do not profess to do the former, and as for the 

 latter we do not find that they are very successful, so far as 

 efficiency is combined with economy. 



Let us revert, for an instant only, to the filtration — 

 intermittent, or downward, or irrigation-filtration, or other- 

 wise — of the Rivers' Commission. We will first describe 

 the construction of such a filtering-bed, and will then 

 take in consideration of the efficacy of this quasi-filtration 

 the evidence of Dr. Frankland. The illustration is the 

 construction of the Merthyr Tydvil beds, described by 

 Mr. T. C. Scott, a strenuous advocate. " The filtering 



