GENERAL DATA.—DinienSi.0118 of Important Parts of Corliss Engines.—James B. Stan wood, in his paper on Stationary-Engine Practice in America, Engineering, June 12, 1801, gives the following table: Limit of in a nen-Cylinder Compound Enyine.—John G. .flair (Proc. fast, 31. B. February, 1887) says, with regard to the number of expansions that could advantageously be made in an ordinary two-cylinder compound engine, the following were the results of experiments that he had made with a raising the boiler-pressure from 60 till to 1:20 lbs. per sq. in. above atmosphere while working throughout at practically the same speed : Boiler-pressure, lbs. per sq. in. above atmosphere. 60 80 100 120 Number of expansions_ Thermal units used per indicated horsepower per minute T14 :327 325 330 These figures showed that, after obtaining somewhere about 10 or 12 expansions, there was no economy in going to any higher expansion with two cylinders, as the saving in heat ex pended was not sufficient to make up for the increased frictional loss due to the larger cylin ders required.
Water-Consumption of Different Types of Enyine.—The following are common figures for t he usual performance of stationary engines used in electrical work in 1800 -Vanua' of the Steam-Engine): lligh-speed, 35 to 40 lbs. water,
" compound, non-condensing 25 to 47 " " condensing 19 to 21 " "" .. 16 to 17 " " 2; to 29 compound. 15 to 16 " " triple • 13 to 14 " " In common practice, with 150 lbs. steam, the temperature being equalized, the ratios of cylinder volumes in the triple-expansion engine are about Possible Impmrements in the Steam-Enyine.—Prof. Thurston says that comparison of results of experience leads to sneh final conclusions as follows: 1. Experilnent, experience, and the philosophy of the steam-engine combine to indicate that the of possible advance in them economical application is now so nearly approached that further progress to be both slow and toilsome.
2. That the range left for such further improvement upon the hest and most efficient of existing engines is probably smell, and the difficulties arising in Lhe attempt to reduce it are incrensimg in a higher ratio than progress in its reduction.
3. That, while wasteful engines may be Unproved by various expedients. including the substitution of other working fluids than steam, either wholly or partly., no other vapor has yet been found to give an economical performance exceeding on the whole, or even equaling. that obtained with the best steam-engines.