60 A Solution of the Sewage Problem. [January, 



medium consists of 20 acres of land, drained 6 feet deep, 

 and divided into four areas of 5 acres each. Each of 

 these receives daily, for six hours out of the twenty-four, 

 the sewage of 20,000 persons, represented by 900,000 

 gallons, or at the rate of 73,000 tons per acre per annum. 

 To utilise advantageously, according to our present know- 

 ledge, the quantity of sewage thus dealt with, 200 acre s : 

 land are required, being at the rate of 1 acre for every 100 

 persons, or for 7,300 tons of this sewage."' Now for the 

 opinion of Dr. Frankland, who is an advocate of the irriga- 

 tion system, and a Rivers' Pollution Commissioner. " I 

 think it (this downward filtration) is an important part of 

 our knowledge; but although I have had so much to do 

 with it, I confess I am not very sanguine of its success as 

 applied to large volumes of sewage, and for this reason : you 

 collect upon the surface of your filters a large quantity of 

 suspended matter from the sewage, which is foecal matter in 

 a state of decomposition, and we should be afraid that this 

 matter so collected would be offensive to the neighbourhood. 

 No plant can live upon the filter which is deluged in this 

 way with sewage. This cannot be carried out along with 

 plant growth, and consequently you have not the removal of 

 those noxious constituents which accumulate on the surface 

 by r'.ant life, such as you have in irrigation." Thus, the 

 filtration of unprepared sewage leaves us with far higher 

 chances of miasma than do the evils of irrigation. 



The process known as Weare's is a true filtration process, 

 and is on a small scale said to be satisfactory. It has been 

 employed in the workhouse at Stoke-upon-Trent ; the fil- 

 tration being effected through vegetable charcoal and fine 

 ash, altogether a different method to the irrigation-filtra- 

 tion system. The filtering medium is placed in tanks 

 through which the sewage percolates. The effluent water, 

 however, still contains in solution a large proportion of 

 putrescible organic matter, and is below the standard 

 required by the Rivers' Pollution Commissioners, or by the 

 Conservancy of the Thames. 



But the evidence brought before the Parliamentary Com- 

 mittee on the Birmingham Sewerage Bill, in April and May 

 last, has, we think, given the death-blow to sewage filtration. 

 After fourteen days' hearing of the evidence of the leading 

 authorities in Chemistry, Engineering, and Agriculture, the 

 Select Committee attached to their approval of the Bill the 

 condition that "No sewage be put upon any land without ha 



s." 



The third scheme of getting rid of sewage, viz., that of 



