~With Discussion by Messrs. Allen Hazen, George A. Johnson,Morris Knowles, George C. Whipple, F. F. Longley, and E. D. Hardy.~ The Washington filtration plant has already been fully described.[2] At the time that paper was written (November, 1906), the filtration plant had been in operation for only about 1 year. It has now been in continuous operation for 5 years, and many data on the cost, efficiency, and methods of operation, have accumulated... more...