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Mr. Binnie. spaces, he considered that no apprehension need be felt on this score, as percolation-beds of this type-for example, those at Cohmbus, Ohio-worked perfectly well a t temperatures very much lower than any which obtained in England. The question whether the degree of dilution affected the amount of filtering-material which should be employed was a very interesting one, and he considered that the experience a t Salisbury rather tended to endorse the view put forward by Mr. Martin. With regard to Mr. Jenkin's question whether the 7-inch pipe to which Fig. 6, Plate 7, applied had burst, as it was under a head of 47 feet, the Author would be very surprised to learn that this had happened. It was true that the difference in level between the two ends of the sewer was 47 feet, and therefore if the lower end of the sewer were blocked, all the intermediate manholes closed, and the pipe filled with water, it would be possible to put the lower end under a head of 47 feet : these, however, were conditions which hardly obtained in practice, as the static head was entirely converted into kinetic energy, so that there could be little or no static pressure on the inside of the pipe. With regard to the discrepancy pointed out by Mr. Jenkin between the total flow of crude sewage to the air-lift pump and of the effluent from the percolation-bed in the 24 hours in Tables I and 11, Mr. Jenkin appeared to have overlooked the foot-note to Table I, which stated that at 9 . 5 0 a.m. five beds were at work, and that the effluent from one of them was not measured. This would account for part of the discrepancy and would bring the figures as near as it was possible to get them within the limits of accuracy attainable by measuring the depth of discharge over the weirs. I n conclusion, he wished to thank Colonel Harding for his valuable contribution to the discussion, with which he thoroughly agreed.Correspondence.. Mr. Anderson.Mr. J. T. NOBLE ANDERSON remarked that it was evident the Authors of the two Papers had attained a measure of success remarkable even in England. Consideration of similar works abroad, and of their history, led him, however, to question the opening quotation made by Mr. Watson, that England's lead in such things was due to her necessity. I n America, and even in the sparsely populated Australian colonies and New Zealand, circumstances and Downloaded by [ University of Sussex] on [16/09/16].

Mr. Morton. delivered directly into his precipitation-tanks. With regard to the use of snifting-valves on large pumps, the statement in the Paper (p. 235) was perhaps too universal, and he was quite willing to say, " were often fitted." I n sewage-pumps the snifting-valve was very useful, but there was no necessity to use it t o such an extent as to seriously reduce the displacement efficiency of the pumps. The pumps described in his Paper could run quite well without snifting-valves. The question as to the efficiencies when the snifting-valves were open was fully answered a t the foot of p. 235. The trials carried out with the engines had been made scrupulously under working-conditions, with ordinary fuel, and without special preparation.