Steam:
Its Generation and Use

were necessarily lost in starting and hauling fires. On this basis the water was evaporated in 12.4 hours, or at the equivalent rate of 13,919 pounds per hour for feed water at 180 degrees. On the basis that any good engine under fair conditions will require but 30 pounds of water per horse- power per hour, your boilers, during this experi- ment, though not forced to their utmost, devel- oped under condition agreed upon, 13919 -s- 30 — 464 horse-power, or 104 horse-power in excess of the guaranteed power. The coal required per horse-power per hour is evidently dependent in any case upon the econ- omy of the boiler and engine jointly. With an of 89.4 pounds from a temperature ioo° per lb. of Cumberland coal; yet the engine was so economical that there was required but 1.69 lbs. of coal per horse-power per hour. The equiva- lent evaporation of your boilers from the same temperature with anthracite nut coal, much in- ferior to Cumberland, on the basis of the trial above mentioned, is 8.547 pounds of water per pound of coal; so if your boilers were used in connection with that particular pumping engine, there would be required but 1.64 pounds of the inferior coal per horse-power per hour. The economical performance of your boilers could undoubtedly be rendered still greater by Boilers. Boiler House and Economizers, with Blast Flue and Ash Tunnel, made for Lombard, Ayres & Co., Seaboard Oil Refinery, Bayonne, N. J.t 15 orders, 2,246 H. P. evaporation of 9.252 pounds of water per pound of coal, and 30 pounds of water per horse-power in the engine, there would be required per horse- power per hour 3.24 pounds of coal. This boiler performance, however, is rarely obtained in ordinary7 practice, so generally a low cost of power in fuel is due to using an excellent engine with a fair boiler. For instance, during the offi- cial trial of one of the most prominent pumping engines in this country, the boilers, which were specially designed to secure economy, actually evaporated but 8.31 pounds of water ata pressure reducing the rate of evaporation. The more fuel burned per square foot of heating surface in a given time the greater the quantity of heat lost in the chimney, so that, within certain limits, using proper proportion, the economy increases as the rate of evaporation is diminished, though in a much less ratio. To accomplish this result to the fullest extent, however, the boiler would probably need to be so proportioned that it would not develop a maximum of 464 horse-power, or up- ward, as in its present form. Very truly, yours, Chas. E. Emery. 84