As to water, the gas motor takes 215 cubic feet per horse power
effective. A condensing steam engine uses five times as much.

The lubricating oil used at Rouen was a mixture of Russian oil at 430
fr. per ton, and Ferry and Heduit F.H. oil at 900 fr.; the average was
650 fr. per ton, or 2.8d. per pound. Wanner grease, at 6.4d. per pound,
was used for the moving parts. A steam engine requires less oil for the
cylinder, but the same quantity for the moving parts.

The attendance on the gas motor is too much for one man, not enough to
occupy two; reckon it at 4s. 9½d. a day.

These elements enable us to calculate the daily cost of the gas motor,
of 75 actual horse power, in comparison with a steam engine of the same
size.

_Steam Engine_.

s. d.
Upkeep, interest and sinking fund at 15 per
cent, on £1,292 = £193.8 = per day. 12 11
Cardiff coal, 2.643 pounds per actual horse
power per hour; 2.643 × 10 × 75 = in 10
hours 1,982 pounds coal at 22s. a ton. 19 5½
Oil, 3.36 pounds per day at 2.8d. per pound. 0 9½
Grease, 0.67 pound at 6.4d. 0 4½
Wages. 4 9½
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£1 18 4