In 1900 some of the waters in their natural state carried too large a number of bacteria for safety, but since that time it is possible that some of the recent processes of purification may have been utilized. The ozone process is adequate to rid such waters of their pathogenic germs. In 1911 modern Rome daily consumed 120 gallons of water for each of its 542,000 inhabitants. During the Roman era it consumed approximately 32,000,000 gallons daily. The remains of Roman aqueducts still exist in Asia Minor, Algeria, France, Spain and else where, showing that the Romans took great pains and went to great expense to provide their cities with the best natural waters obtainable. Some of the aqueducts were of superb con struction, as were the Pont-du-Gard, the aque duct at Segovia and the Aqua Claudia, extend ing along the Roman Cam Naples obtains its suTin part from ground waters collected infiltration galleries 2,000 feet or more in length, constructed in a stratum of gravel 30 feet below the surface, wherein are daily collected *000,000 gallons. Five parallel tunnels have been formed in the old quarries of Capodimonte for impounding such waters. The Apulian aqueduct in the southeastern part of Italy is of masonry con struction for 151 miles. Its main trunk line and lateral branches altogether are 1,690 miles in length. Its waters supply 152 service reser voirs and nearly 2,000,000 of people. Italy has both the Alps and the Apennines to intercept the vapor-laden clouds. whose waters supply it many streams and its dense population.
Paris has two general systems for supplying water under different pressures, namely. (1) a high-pressure system for its domestic or potable supply, (2) a low-pressure system for industrial, street-cleaning and general municipal, other than potable purposes.
1. Paris obtains its high-pressure supply for domestic pit/poses from four sources, namely, (a) from the springs that are tributaries of the Vanne River 106 miles distant, conducted through the Vanne aqueduct into the two-story reservoir at Montrouge 262 feet above sea level; from springs that are tributaries to the Loing and Lunain rivers, whose waters are conducted through the Loing and Lunain aque duct into the Monsoons reservoir (that sup ply and the Syphon aqueduct are described and illustrated in Derivation du Sources du Loing at du par Beckmann et Babinet, published at Paris 1905); (c) from the Dhuis springs 82 miles distant, flowing from the east through the Dhuis aqueduct into reservoirs at Meniontant having an elevation of 354 feet above the sea, and (d) an additional supply for domestic purposes from the springs of the Awe, 63 miles west of the city, flowing through an aqueduct into Saint Cloud reservoir. Dur ing the World War the Dhuis supply was cut off and the demands on the other sources were greatly increased.
2. Paris obtains its low-pressure supply for industrial and general municipal, other than potable, purposes from the Seine pumped at Ivry and at other places on that river and from the Marne at Saint Maur and from the Ourcq Canal and from artesian wells, and water is also obtained through the Arcueil aqueduct from Rungis.
The works at Saint Maur include sedimenta tion basins, sand filters, ozone sterilizers and a bacteriological laboratory. In pre-war 1914 conditions, the raw Manic water carried 12,000 B. coli per cubic centimeter. After passing the sand filters these were reduced to 300, which disappeared as the water passed through the ozone sterilizers. An additional supply for domestic purposes was found neces sary and river water was thoroughly treated, purified and used The entire supply for do mestic and potable before the World War was about 40 Ions per day for each resident of the city.e supply for other mu nicipal purposes is three times per capita the amount used for domestic and potable pur poses. Since the World War, the Marne and other rivers in northeastern .France, in which are countless human remains, have carried a great increase of pathogenic and other bacteria. The water supply of the entire war zone has been polluted.
The ozone treatment was so successful at Saint Maur that it was adopted by the mu nicipality of Paris to purify the water of the Seine, taken to supplement itsgeneral mu nicipal water supply. Miguel in 1896 found 300 bacteria per cubic centimeter in the Seine above Paris and Clichy found 200.000 bacteria per cubic centimeter in the Seine below Paris.
The Belleville reservoir has two stories. The upper receives water from the Dhuis aque duct and the lower from the river. The Mont rouge receives water from the.Vanne aqueduct into its upper stories and water from the riser into its lower story. The Montmartre reservoir receives spring water into its three upper stories and river water into its lower story.
The %amr supply of the city of London is obtained from the yield of the watersheds of the Thames. the Lea and the New River, com prising an area of 620 square miles and from springs and many wells in those watersheds sad in the chalk deposits of Kent. Formerly aght or more companies pumped the water from the Thames, the Lea and the New rivers and from springs and wells into 65 or more reservoirs. Some of the principal ones were included in the works of the New River Com palsy. the East London Waterworks Company, The Southwark and Vauxhall Water Company, die Company of the West Middlesex Works, the Company of Proprietors of Lambeth Water works, The Gqvernor and Company of Chelsea V‘'aterwork.s_ The Grand Junction Waterworks CnaaPliny, The Company and Proprietors of the Kent Waterworks and The Staines Reser scars Joint Committee, supplying Kempton Park reservoir. In the literature on the subject these utles are omitted and the popular names of particular companies are used.