180 POPULAR SCIENCE MONTHLY. 



system could be operated with less difficulty and with somewhat less 



expense. 



In 1896 the city of Pittsburg, Pa., appointed a commission to con- 

 sider the character of the water supply and the advisability of its puri- 

 fication by some means of filtration. The supply is taken from the 

 Allegheny and Monongahela rivers, streams which are often turbid 

 and which are subject to contamination by sewage. The conditions were 

 such that direct experiment was necessary to determine the most suit- 

 able system of purification. Accordingly, an experimental station was 

 located on the shore of the Allegheny Kiver and placed in charge of 

 Mr. Morris Knowles, under the direction of Mr. Allen Hazen, Consult- 

 ing Engineer. Arrangements were made for the comparative study of 

 sand filters and mechanical filters, and a laboratory was built and 

 equipped for making all necessary analyses. The plant was in continu- 

 ous operation for more than a year, and the results seemed to show that 

 while satisfactory clarification of the water could be obtained by either 

 system, the method of sand filtration could be depended upon to remove 

 more completely the effect of pollution. 



The report of a similar series of experiments made to determine the 

 feasibility of purifying the water of the Potomac River at Washington, 

 D. C, has been issued by the War Department. The work was carried on 

 in a manner similar to that at Cincinnati and Pittsburg, the object of 

 the studies being to find the best method adapted to the local conditions. 

 Col. A. M. Miller, XJ. S. A., had charge of the investigations, and Mr. 

 Robert Spurr Weston conducted the analytical work. Recently the 

 Department of Public Works, of Philadelphia, Pa., has established 

 a testing station near the Spring Garden Pumping Station for 

 the purpose of studying the problems of filtration incident to the con- 

 struction of filter beds for the water supply of the entire city, for which 

 the sum of ten million dollars has been already appropriated. The work 

 is in charge of Mr. Morris Knowles. Still more recently a testing station 

 has been established by the Sewerage and Water Board of New Orleans, 

 with Mr. Robert Spurr Weston as Resident Expert. 



In July,1899,the newly-constructed water filtration plant at Albany, 

 N. Y., was put in operation, Mr. Allen Hazen having been Chief En- 

 gineer of construction and Mr. Geo. I. Bailey Superintendent of Water 

 Works. In connection with this plant is a small laboratory in which are 

 made daily bacteriological examinations of the water before and after fil- 

 tration. Physical, chemical and microscopical examinations are also 

 made at frequent intervals. The results obtained indicate the amount 

 of purification that is taking place, and they already have shown that 

 the filter is rendering efficient service in protecting the community from 

 water-borne diseases. 



The combined work of these various laboratories of supervision and 



