The cost of constructing water-works varies very much, according to local features, geological structure, and kind of scheme most suitable to the place. In Great Britain, gravitation schemes cost from $10 to $13, and pumping schemes from $7 to $10, per inhabitant. The average cost per head, for London, was $20; for Liverpool, $20; for Bradford, England, $35; for Halifax, England, $25; for Dundee, Scotland, $30; for Glasgow, $15; for Manchester and Sheffield (each) $12 per head.

The average cost for a supply of 20 imperial gallons per day, per head, for 66 towns of Great Britain having gravitation supplies, was $8; for 48 towns, with pumping system, $5.80; and for 11 towns, having both systems, $7. From the annual report of Chicago, for 1880, we take the following cost, per capita, for water-works construction: Detroit, $23.11; Newark, N. J., $19.08; Wilmington, Del., $20.73; Buffalo, $18.29; Cincinnati, $26.20; Milwaukee, $19.25; Columbus, O., $18.14; Louisville, Ky., $25.04; Cleveland, O., $16.84; Providence, R. I., $52.74; Boston (gravity supply), $44.46; Manchester, N. H. (water pumping power), $24.24; Hartford, Conn. (gravity), $35.60; New York (gravity), $34.38, St. Louis, $26.07; Chicago, $17.49.

The Engineering News, of New York, Vol. IX, No. 4, contains valuable tables on construction, and other valuable water-works statistics, from which the following is compiled:

REVENUE AND EXPENSE.

The average water-rent receipts, for 1880, per mile of water pipe in use, was $2,022 for Chicago, $3,200 for New York, $1,932 for Philadelphia, $2,730 for Boston, $3,307 for Brooklyn, $2,183 for Baltimore, $3,112 for St. Louis, $2,647 for Cincinnati, $1,600 for Louisville, $1,611 for Cleveland, $1,821 for Detroit, $2,060 for Buffalo, $1,500 for Milwaukee, $1,746 for Indianapolis; $1,128 for Columbus, Ohio, $3,556 for Pittsburgh, $397 for Washington, and $618 for Toledo, Ohio.

The cost of maintenance, for stand-pipe system, varies from 10 to 90 per cent. of revenue; for direct pumping, from 30 to 140 per cent. of revenue; for reservoir pumping, for large cities, from 12 to 37 per cent. of revenue; for small cities, from 12 to 120 per cent. of revenue; and new works, from 12 to 60 per cent. of revenue; for gravitation works, from 13 to 120 per cent. of revenue.

The revenue and the cost of maintenance (exclusive of interest), for each 1,000 gallons of water pumped, are respectively: Philadelphia, 5.77 and 1.28 cents; St. Louis, 6.91 and 2.55 cents; Chicago, 4.12 and 1.18 cents; Detroit, 4.09 and 82 cents; Buffalo, 3.50 and 1.00 cents; New York, 4.7 and one cent; Cleveland, 5.43 and 1.5 cents; Cincinnati, 7.01 and 2.6 cents.

The revenue received, for each 1,000 gallons delivered, is 15.52 cents at Liverpool, England; 14.35 cents at Berlin, Germany; 8.13 cents at Dresden, and 4 cents at Hamburg.

The comparative annual water-rent charges for a large house, in different cities, are as follows: Columbus, Ohio, $23.50; Lawrence, Mass., $20; Providence, R. I., $31; Brooklyn, $29.25; Buffalo, $43.50; Detroit, $23.25; Cincinnati, $28.73; Cleveland, $21.50; Chicago, $34; Philadelphia, $27.75; Pittsburgh, $71.50; Milwaukee, $34.50; Louisville, $51.50.

The meter rate charges, per 1,000 gallons, are 10 to 40 cents at Boston; 10 cents at Chicago; 10.2 at Cincinnati; 7 to 20 at Columbus, Ohio; 15 cents at Brooklyn; 13½ at Baltimore; 6 to 12 at Cleveland; 20 to 30 at Buffalo; 15 cents at Philadelphia; 7½ cents at New York; and 30 cents at Providence, Rhode Island.

The meter rates, per 1,000 U. S. gallons, at Stuttgart, Germany, are 11 cents for filtered river water, 5½ cents for lake water, and 15 cents for spring water. The rates, at Frankfort-on-the-Main, are 3.7 to 5 cents; at Hamburg, Germany, 8½ cents; at Leipsic, 7½ to 9¼ cents; at Berlin, Germany, 6½ to 25½ cents; at Dublin, Ireland, 6½ to 11 cents; and at Glasgow, Scotland, 15 cents per 1,000 U. S. gallons.

The average dividend paid by the water companies of Great Britain, in 1870, was 7 per cent.

WATER PIPES.

The different kinds of water pipes in use are made of wood, cast-iron, wrought-iron, and glass. For adapting wrought pipe to practical use, various methods have been resorted to, that of coating with asphaltum, enameling, galvanizing, and lining inside and covering outside with cement. The latter method has been adopted by a number of water-works; but the liability to corrosion, from imperfect work and material, has caused its abandonment in a number of places. The Spring Valley Water Company, of San Francisco, have in use a number of wrought-iron riveted pipes, coated with asphaltum, of 20 to 42 inches in diameter. They are made of No. 12 to 14 iron (Birmingham wire gauge), and have a hydrostatic pressure upon them of from 200 to 400 feet. Virginia City (Nevada) water-works laid two lines of wrought-iron pipe across the Washoe Valley, 7½ miles wide—one of 12-inch riveted pipe, and the other of 10-inch enameled, lap-welded tubes. The pressure on the pipe at the bottom of the valley is 750 pounds. The enormous pressure has caused a number of rivets to give out. On the test for the respective capacities, the 10-inch pipe delivered 2½ millions per day, against two millions for the 12-inch pipe.

Hard water has but little effect on cast-iron pipe, due to the carbonates; but soft water attacks it so vigorously, that it not only gives a turbid appearance to the water, but seriously weakens the pipe by corrosion, and the consequent formation of concretions that reduce the capacity of the pipe. Hard water also causes the formation of lime deposits, that offer great impediments to the flow of water. These obstructions are now removed by boring tools forced through the pipe by the hydrostatic pressure. The Superintendent of the Halifax (N. S.) Water-Works records the cleansing of a 12-inch main, 32,000 feet long, in three-fourths of an hour. The preservation of cast-iron pipes, and the prevention of these concretions, are now accomplished by carefully dipping the pipe, previously heated to a temperature of 300 degrees, in a bath of distilled coal tar, mixed, to a proper consistency, with linseed oil, or an oil of the tar.

The Rivers Pollution Commission condemned the common practice of using hemp in pipe joints, because it affords a nidus for the breeding, development, and decay of animalculæ. Turned joints were recommended.

The results of the observations of this commission prove conclusively than the commonly received opinion, that soft water necessarily acts upon lead pipes, is erroneous. The Loch Katrine water, which is notorious for dissolving lead in water exposed to the open air, yet no symptoms of lead poisoning have been discovered since its introduction, eighteen years ago. The water will act upon the lead at first, but will ultimately coat the inside of the pipe with a vegetable deposit that prevents further deterioration.

The frictional head, for a given diameter, is as the square of the velocity nearly; and, for different diameters, inversely as the diameters. Thus the loss of head, for each 100 feet of clean cast pipe, the velocity being three feet per second, is 1.35 feet for a 3-inch pipe; 1.02 for a 4-inch; .679 of a foot for a 6-inch; .407 of a foot for a 10-inch; .255 for a 16-inch, and .204 of a foot for a 20 inch pipe. The mean coefficient of friction, for cast-iron pipes of small size, with velocities of three feet, is .00644 for clean pipe; .0082 for slightly tuberculated pipes, and .012 for foul pipes.

WEIGHTS OF CAST-IRON PIPE,

WITH ALLOWANCE ADDED FOR BOWL AND SPIGOT ENDS.

Weights in columns per foot lineal. Iron .2604 per cubic inch.

WATER-WORKS STATISTICS

FROM REPORTS FOR 1880 AND 1881.