776 PROCEEDINGS OF SECTION H. 



In tlie 50 yards flow from the man-hole to tlie tanks the 

 sewage and i'erozoue get well mixed together. The sewage 

 in the tanks may be said to be always stagnant, that is, in 

 the condition favourable to sedimentation ; for, as the sewage 

 pours out of a comparatively small sewer into a tank 100 feet 

 long by 60 feet wide, its i-ise in the latter is a very slow 

 motion. When one tank is full the sewage from the sewer 

 is turned into the other, which has been emptied to receive 

 it. The full tank is allowed to stand for two hours longer, at 

 the end of which time the water has become clear. As the top 

 water is naturally the clearest, in emptying the tank the water 

 is always drawn oft' from the top by a well known arrangement. 

 If the state of the tide permit, the whole tank is emptied by 

 gravitation. If the height of the tide does not permit this, 

 the water that cannot be so discharged is discharged by one 

 of Shone's ejectors ; and there is a special arrangement to 

 prevent it from discharging any of the precipitated mud — 

 the sludge — with the water. This efiluent water is superior 

 in purity to the effluent from the electrolytic process, for not 

 only is all the suspended matter in the sewage precipitated, 

 but with it 90 per cent, of the dissolved organic matter, as 

 compared with the before-mentioned 57 to 80 per cent. It is 

 also superior in purity to the effluent waters from the sewage 

 farms at Croydon and at Adelaide, according to analyses 

 kindly given to me by the engineers-in-charge, Mr. Walker, 

 the Borough Engineer of Croydon, and Mr. Bayer, the 

 Sanitary Engineer to the Government of South Australia. 

 And furthermore, this effluent water is deprived of its 

 liability to putrefy. I saw samples that had been kept for 

 months showing no signs of putrescence. 



I take it that 1 have thus shown how the watery part of 

 the sewage may be, and is, satisfactorily disposed of without 

 ]iossibility of creating a nuisance in a tidal river or the sea. 

 There is nothing left in it to be deposited on the shores, or to 

 form mud-banks ; and if pools of it are left stagnant they 

 will not ferment and make bad smells. The more solid part, 

 the sludge, has still to be dealt with ; and, in the first place, 

 it has to be got out of the bottom of the precipitating tanks. 

 As in describing how this should be done I have again to 

 refer to Shone's ejectors, I will make a little digression about 

 them, as from current talk, even among people who profess 

 to know^ all about them, their capabilities are but little under- 

 stood, and they are considered as part of Messrs. Shone and 

 A>dt's Hydro-Pneumatic Sewage System, and nothing else. 



