THE RECORD OF FILTRATION.
A review of the progress made in water works administration shows that no branch has equalled that of mechanical filtration. In an article in the convention issue of FIRE AND WATER ENGINEERING this remarkable advance was outlined and a table of filtration plants now in operation in the United States and Canada given which substantially bear out the statements of the engineers as to the efficacy of water purification by mechanical processes. Two decades have seen mechanical filtration advance from the point where it was still regarded somewhat in the light of an experiment to that where experts pronounce it as a most efficient method. With 550 plants in operation, all of which are giving satisfaction, it is evident the system has positive merit, for in these many plants a great variety of conditions, both as to character and extent of the work, have been met and successfully treated. George A. Johnson, C. E., stated that over thirteen million people in North America arc supplied with water filtered by mechanical filtration, and that during the past four years, plants to serve over four million people have been built, while Nicholas S. Hill, Jr., says: “Mechanical filtration has made very rapid strides in this country and has far outdistanced sand filtration in the number of plants installed and quality of water filtered.” In a paper read by George W. Fuller, C. E., on “The Croton Water Supply,” he took occasion to present much material favorable to mechanical filtration. These and other expressions by engineer experts indicate how American or mechanical filtration is gaining so rapidly in favor. This, however, is not remarkable when its adaptability to almost all conditions, low cost of construction and simplicity in operation are taken into account.