A horse-power is estimated as capable of raising 33,000 pounds one foot high per minute, and for this reason it is termed 33,000 foot pounds per minute. So we have 33,000 x 60 = 1,980,000 foot pounds per hour, as a horse-power. The best class of _compound condensing_ engines,[3] with all the modern improvements, require 1.828 pounds of coal per 1 h.p. per hour. Thus we have-- 12,175,984 x 1.828 .................22,257,699 Foot pounds in one h.p. .............1,980,000 ---------- Foot pounds lost per h.p. ..........20,277,699 Per cent utilized per h.p. ..............8.94 Per cent lost per h.p. .................91.06 ------ 100.00 [Footnote 3: "American Engineer," Vol. II., No. 10, page 182.] In the ordinary practice of stationary non-condensing engines, from three to four pounds of coal are required per horse-power per hour. Now, taking the best of this class at 3 pounds, we have-- 12,175,984 x 3 = 36,527,952 One h.p. 1,980,000 ---------- Loss per h.p. 34,547,952 Per cent utilized per h.p. 5.42 Per cent lost per h.p. 94.58 ------ 100.00 From these facts it may be assumed that after making due allowance for variable qualities of the coal, the steam engine process, as at present practiced, will not utilize more than from 5 to 10 per cent. of the energy contained in the fuel used. It will thus be seen that the process of converting static to dynamic caloric by luminous combustion, by means of the steam engine, is an exceedingly wasteful and costly method, and leaves much room for economy. Taking an ordinary grade of petroleum as consisting of 13 per cent. hydrogen, 78 carbon, 6 oxygen, 3 nitrogen and ash, we have as its energy in foot pounds per pound of oil-- 62,391 x 13 } ----------- = 8,110 H. } 100 } } 19,454 units. 14,544 x 78 } ----------- = 11,344 C. } 100 } 19,454 x 772 = 15,018,488 foot pounds. Thus, while our best coal contains twelve million, the petroleum contains fifteen million foot pounds of occluded energy in each pound, which is equal to 118,000,000 foot pounds, or 60 horse power for one hour, from one gallon of such oil.