and purifying the Thames Water. 691 



the disadvantage of producing malaria in the neighbourhood of the basins 

 where the contents were left for settling, running off, filtration, and drying. 



Instead of one main sewer, or one aqueduct or more, form a well at 

 the mouth of every sewer where it enters the Thames; filter off whatever 

 is larger than an inch in diameter, and force through underground pipes, 

 of adequate capacity and strength, all the liquid contents of the sewers 

 several miles' distance into the ^country for evaporation and desiccation. 

 However expensive this might be, there can be no doubt of its practica- 

 bility. Notwithstanding the large size of the sewers, there are few if any 

 of them that deliver, at an average, more fluid matter than would pass 

 through a pipe of 2 ft. in diameter; the contents of some of them, we are 

 persuaded, would not, at an average, fill a pipe of 1 ft. in diameter. 



A better plan, and, we think, the best, would be to construct a building, 

 50 or 60 ft. high, rectangular, and from 50 to 100 ft. in diameter, over the 

 mouth of each sewer. In this building there might be 50 or 40 floors, at 

 about a foot apart, each floor being a grating or filter; commencing at 

 the top with a filter of wire with the meshes half an inch apart, and ending 

 with a floor of sponge. The contents of the sewer, after passing through 

 a grating to separate bones and other matter above an inch in diameter, 

 might be pumped up to the upper floor by the power of steam, every floor 

 being in, say eight divisions. The discharge from the pumps might easily 

 be so contrived as to be delivered for about five minutes at a time into the 

 top floor of each division. From this it would filter to the bottom floor, 

 gradually becoming purer and purer, leaving a deposit of different degrees 

 of fineness on each floor, and coming out pure water. This would give 

 half an hour to the deposit on each floor to dry, and to be brushed off by 

 machinery into vats or boxes, where it might be compressed into cakes for 

 sale. The bones and other bulky matter separated by the first filter or 

 grating, before the liquid matter entered the well from which it is to be 

 pumped, might be passed through a bone mill, to be worked by the same 

 machinery, and would be found not the least valuable part of the manure. 

 Perhaps it might be worth while to mix the ground bones, and other 

 bulky matters ground along with them, v^ith the finer matter pi-ocured by 

 filtration, adding a little quicklime; by this means the cakes would be less 

 liable to break by carriage. 



The average discharge of any sewer being ascertained, it would be easy 

 to determine the proportionate size of all the apparatus, and the whole 

 might be roofed in with glass to admit the influence of the sun, while the 

 sides might be formed of open weather-boarding, like the late horizontal 

 windmill at Battersea, in order to admit a free circulation of air. The 

 cakes of manure, or poudrette cakes, might be dried in a separate building, 

 or set up in walls and thatched in the manner of unburnt bricks, mushroom 

 spawn, or turves cut from peat bogs to be dried for fuel. 



After the water had passed through the last filter of sponge, it would at 

 least be free from all the impurities it held in mixture ; and though there 

 would remain the impurities held in combination, still these would be 

 nothing like what mix with the water of the Thames at present. 



We cannot help thinking that an apparatus of the sort contemplated, 

 placed at the Chelsea Dolphin, would pay as a manure manufactory : and 

 it may be worth while for the government and the water companies to 

 consider how far the establishment of similar manufactories, at the mouths 

 of all the sewers, would contribute to render the Thames water sufficiently 

 wholesome for domestic purposes, which it is acknowledged not to be at 

 present. Perhaps the time may come when the 140 sewers, which empty 

 themselves into the Thames between Deptford and Battersea, may be let 

 out to manure manufacturers by the city of London, as toll-gates now are. 



Y Y 2 



