ox THE TREATMENT AND UTILIZATION OF SEWAGE. 135 



temperatures, and also at a red heat, at which latter temperature the resist- 

 ance Avas about three and a half times as great as at atmospheric tem- 

 peratures. After being heated, it was found that the resistance of the 

 pyrometer was slightly greater at a low temperature than it liad been at the 

 same temperature previously ; but the permanent change which thus took 

 place became smaller and smaller after successive heatings, so that the 

 instrument may be expected to reach a condition in which no further im- 

 portant alteration will be produced in it by exposure to a red heat. 



The Committee are, however, informed by Mr. Siemens that he believes 

 that the small amount of variation to which the pyrometer, as hitherto con- 

 structed, was thus found to be subject, may be considerably lessened, or 

 altogether prevented, by an easy alteration in the mode of enclosing the coil. 

 Under these circumstances it is considered desirable to postpone further trials 

 until the more perfect form of the instrument can be experimented with ; the 

 Committee, therefore, suggest that they should be reappointed, and that the 

 grant of =£30, made at the last Meeting, none of which has been expended, 

 should be renewed. ... 



Fourth Report of the Committee on the Treatment and Utilization of 

 Sewage, consisting 0/ Richard B. Grantham, C.E.,F.G.S. (Chair- 

 man), Professor W. H. Corfield, 31. A., M.D., *J. Bailey Denton, 

 C.E., F.G.S., Dr. J. H. Gilbert, FR.S., * John Thornhill Har- 

 rison, C.E., W. Hope, V.C, *Lieut.-Col. Leach, R.E., Dr. A. 

 Yoelcker, F.R.S., and Professor A. W. Williamson, F.R.S. 



N.B. — Those members whose names have an asterisk prefixed have not attended any 

 meeting of the Committee during the year. 



The Committee, since its reappointment at the last Meeting of the Associa- 

 tion at Edinburgh, has pursued the inquiry intrusted to it, and, as heretofore, 

 its investigations have been limited to such matters as have afforded the 

 promise of practical utility. Among the various methods of treatment or 

 utilization of sewage brought to the notice of the Committee, that of treating 

 sewage by Messrs. Weare's process at Stoke Union AVorkhouse, the precipi- 

 tation and conversion of the deposited matters into cement at Ealing, and 

 the system of intermittent downward filtration at Merthyr Tydfil have 

 appeared most important ; and they have accordingly been investigated, the 

 results appearing in Sections I., II., & VI. of this Report. A process known 

 as Whitthread's patent has been also examined by experiment on a suffi- 

 ciently large scale, and the result is given in Section III, 



The Committee having reported upon the sewage-farms at Tunbridge WelU 

 and Earlswood at the last Meeting of the Association, it was thought 

 advisable to iuspect them again, as the works were incomplete when the 

 Committee last visited them. 



The observations at Breton's Parm have been proceeded with uninter- 

 ruptedly, and are described in Section VII. of this Report. It is only neces- 

 sary to add here that these investigations have now extended over a period 

 of more than two years ; and the experience thus gained from the continuous 

 records of the flow, and sampling for analysis, of the sewage and effluent water, 

 of the application of the sewage to the various crops, of the results of such 



