The 30,000,000-gallon engine at the Chestnut Hill high-service station of the Metropolitan waterworks system, Boston, Mass., was designed and built by the Allis-Chalmers company, of Milwaukee, Wis. It is of the vertical, tripleexpansion, self-contained type, with three singleacting, outside packed plungers, having at contract speed (about seventeen and one-half revolutions per minute) a capacity of 30,000,000 U. S. gals, of water in twenty-four hours. The contract provided that it should perform a duty of 150,000,000 ft. lbs. for each 1,000 lbs. of commercially dry steam used by the engine and auxiliary pumps, the steam containing not less than one and one-half per cent, of entrained water, as determined by calorimeter measurement to be based upon plunger-displacement, with bonus of $1,000 for each 1,000,000 ft. lbs. and a forfeit of $2,000 for each 1,000,000 ft. lbs. or fraction below that guaranteed—the highest ever specified up to the time the contract was let. The official test of the engine showed a duty of 1715,497,000 ft. lbs. per 1,000 lbs. of dry steam, including steam used by all auxiliaries, working under a total lift of 140 ft., with steam at a pressure of 185 lbs.—earning thereby a bonus of $26,051.50. The following are statistics relating to the operation of the engine, showing the economy maintained from 1901 to 1904, each inclusive:

1900.—Total quantity pumped (1,000,000 gallons), 8,923.39; total coal used (lbs.), 5,627,514; gallons pumped per lb. of coal,–T,473.72; average head pumped against (ft.), 125.34. Cost of fuel, average per ton. 2,240 lbs., $4: cost per 1.000,000 gals, pumped to reservoir, including labor, repairs and renewals to engine, boilers and piping, oil, waste, packing and small supplies, $2,832; cost per 1,000,000 gals, raised one ft. high, including some items, $0,023.

1901.—Pumpage (1,000,000 gals), 8,584.11; coal used,6,346,061 lbs.; pumped per lb. of coal, 1.352.67 gals.; head pumped against, 126.31 ft.; cost of fuel, av. per ton, $4.44; cost per 1,000,000 gals, (as above), $3,168; per 1,000,000 gals, as above, $0,025.

1902.—Pumpage (1,000,000 gals.), 10,118.61; coal used, 8,078,166 lbs.; pumped per lb. of coal, 1,252.59; av. head pumped against, 128.43 ft. I cost of fuel, av. per ton, $4.85; cost per 1,000,000 gals., as above, $3,802; cost per 1,000,000 gals., as above, $0,030.

1903.—Pumpage (1,000,000 gals ). 9,631.32; coal used, 8,177,358 lbs.; pumped per lb. of coal, I,177,80; av. head pumped against, 127.63 ft.; cost of fuel, av. per ton, $5.34; cost per 1,000,000 gals., as above, $3,977; cost per 1,000.000 gals., as above, $0,031.

1904.—Pumpage (1,000,000 gals.), 10,522.75; coal used, 8,656,737 lbs.; pumped per lb. of coal, 1,215.56; av. head pumped against, 129.30 ft.; cost of fuel, av. per ton, $3.87; cost per 1.000,000 gals., as above, $2,810; cost per 1,000,000 gals., as above, $0,022.

The test lasted twenty-four hours. The diameter of the cylinders was 30-in.. 56-in. and 87-in.; stroke of engine, 66-in.; diameter ot plungers, 42-in.; stroke of plungers, 66-in.; piston speed per minute, 195.14 ft.; average revolutions per minute. 17.74; total water pumped during test, 30,313.911 gals.; total water fed to boilers. 201,589.5 lbs.; coal per T. H. P. per hour (including auxiliaries). 1.062 lbs.: total coal burned (twentyfour hours), 19,612 lbs.: total ashes and clinkers, 952 lbs.; total combustible. 18,660 lbs.

The same company has built two centrifugal pumps for the Thirty-ninth street pumping station at Chicago, Ill. Their capacity is 75 cu. ft. per second. Chicago has eleven pumps of this type installed; Boston ffor its sewerage system), nine, and Washington, D. C.. twelve. The engines for the Thirty-ninth street, Chicago, station are of the triple-expansion type, the three connecting rods being arranged to connect to a common crank-pin. the crank revolving in a horizontal plane. The cylinders are set at angles of 120°. this arrangement giving a steady effort to the crank-shaft and doing away with the necessity of a flywheel. The areas of the passages are so designed as to reduce the friction to a minimum and allow objects usually found in sewage to pass through, without choking the pump. The weight and thrust of the impeller and shaft are taken up bv a self-aligning and adjustable thrust hearing. Such pumps are necessarily operated against varying heads and must handle varying quantities of water. For this the steam engine is admirably adapted, as its speed is adjustable through very wide limits, thus enabling the pump to be run at its most advantageous speed under these varying conditions. The engines may be simple or compound, condensing or non-condensing, as desired, and can be built as high as 165,000,000 gals, per twenty-four hours.

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