In France it has been generally estimated at 19,195 litres (one inch) for 1,000 inhabitants. The Scotch engineers do not consider the supply complete at less lhan nine gallons a day for each individual in a city. If we compare the distribution of water in London with the population, the supply is at the jate of 20 gallons for each person. But there are no public fountains in that city, and the people receive no water but what is furnished by independent companies. At Paris, 4000 inches of water of Ourcq are appropriated for fountains and for cleaning streets, so that water is raised from the Seine for domestic use. The actual quantity thus used does not exceed 200 inches, (equal 135,584 cubic feet daily,) and it costs, from an accurate and detailed estimate, the enormous sum of 4,265,756 francs, equal to $767,836. To supply the want of Seine water, on account of its cost, pumps are employed in nearly all private houses, and spring and well water is used, although it does not possess the qualities suitable for mechanical industry.

66 PRELIMINARY ESSAY. " Great inconvenience arises among engineers and hydraulicians, from the want of a standard unit, to denote the quantity of water flowing in a given time. The fountaineer's inch (pouce d> eau de fontainier) is used by all French writers upon the subject, though admitted by most of them to be very indefinite. It is perhaps sufficiently correct for practical purposes, but not adopted in philosophical investigation. Genieys says, it is equal to the quantity of water a pipe an inch in diameter would furnish in a minute, so (