As the work progressed, its scope became broader, so much so that the author was induced to depart somewhat from the original idea, and arrange the plan in a more comprehensive form for general use. To condense a large amount of information in a few pages, so as to make it interesting as well as intelligent, is a work requiring patience and diligence. While the work may be of little service to the profession, it is hoped those connected with water-works and the general reader will find sufficient compensation for the time lost in its perusal. The authorities quoted are the highest, and the general facts are from the most reliable sources. Considerable space is given to pollution of water, believing it to be the most important question that bears on the subject before us. Water-works officials will find useful information in the work, which is so frequently desired and sometimes difficult to obtain. Due acknowledgments are made for information derived from the following works: Rivers Pollution Commission, (London,) 1874; Humber’s Water Supply of Cities and Towns; Fanning’s Water Supply Engineering, (New York,) 1876; History and Statistics of American Water-Works, by J. James R. Croes, C. E., Engineering News, (New York,) 1881; Hughes’ Water-Works, Weale Series; Hydraulic Engineering, Weale Series; Die Städtische Wasserversorgung, Von E. Grahn, (München,) 1878; Practical Hydraulics, by Thomas Box, (London,) 1873; Kirkwood’s Filtration of River Waters, (New York,) 1869; Ohio State Geological Works, 1870; U. S. Census Reports, 1881; The National Board of Health Bulletins; The Sanitary Engineer and Engineering News; Catch Water Reservoirs, by C. H. Beloe, London. January, 1882. T. J. B. HISTORY OF WATER SUPPLY. CHAPTER I. It is an historical fact that the water supply of Rome, during the first century of our era, was so abundant “that whole rivers flowed through the streets of Rome.” The quantity was estimated at 375 million gallons per day, an equivalent to 375 gallons for each inhabitant. This supply was conducted to the city through nine costly and marvelous conduits of brick and stone, that tunneled hills and crossed rivers and ravines in the boldest manner, presenting most skillful engineering ability. The number was afterwards increased to fourteen. The principal aqueducts were: Aqua Martia, erected B. C. 431, was 38 miles in length, part of which was composed of 7,000 arches. Aqua Claudia, a subterranean channel for 36¼ miles; 10¾ miles a surface conduit, 3 miles a vaulted tunnel, and 7 miles on lofty arcades, had a capacity for delivering 96 million gallons daily. New Anio was 43 miles in length. Some of these aqueducts were made of three distinct arches, one above the other, that conveyed waters from sources of different elevations.