1XXX. ABSTRACT OF PROCEEDINGS. 



Mr. J. M. Smail, m. inst. c.e.. read a paper entitled "Fil- 

 tration of Water." 



The author described the filtration systems of some of the 

 principal waterworks in Great Britain, Europe, and America 

 recently visited by him, pointing out the characteristic 

 features in each. He dealt with the subject under two 

 heads: first, European method or "Slow Filtration," second 

 American method, " Rapid or Mechanical Filtration." 

 Tables were given shewing the constructive character of 

 the filter beds employed by the London Water Companies 

 and some of those in use on the Continent of Europe and 

 in America, the capacity of the London subsiding and stor- 

 age reservoirs and the average rate of filtration per square 

 foot per hour. After explaining the processes of sand 

 filtration the author quoted the regulations of the German 

 Government drawn up under the direction of Dr. Koch for 

 maintaining the efficiency of filtration beds. 



He dealt with the rate of filtration, the amount of puri- 

 fication required, the cleansing and filling of the filters and 

 other important details in the management of waterworks. 

 The results of bacteriological examinations of water were 

 given for the London and other waterworks in England. 

 The question of preliminary roughing filters was alluded to 

 witli special reference to those in use in Paris. The depth 

 of sand, the quality and size of the grains, and the various 

 methods adopted for the selection and the measuring of the 

 uniformity of the sand in Europe and America was described. 

 He described the American practice of Slow Filtration 

 giving a detailed account of the works at Lawrence, Mass. 

 Under the heading of Rapid or Mechanical Filtration he 

 treated of the aggregation and deposit of suspended matter 

 by means of coagulants ; he also gave a lucid description 

 of a large installation at Little Falls for the supply of the 

 City of New Jersey, detailing the works, the washing of 



