458 moleswoeth’ö pocket-book
Duty of Engines.
The duty of an engine is the number of pounds
raised 1 foot high by a bushel of Welsh coal, or
94 pounds (or by 1 cwt. in recent practice).
Average duty of Cornish engines 60,000,000
= 60 millions of pounds raised 1 foot high.
= 71J millions for 112 lb. standard.
I) = Duty of an engine in millions of pounds.
C = No. of lbs. of coni consumed per indicated
horse-power per hour.
T 186*12 „ . , , 221-76
D = ———- for bushels; = ■—~— tor cwt.
V
Fuel.
AVERAGE EVAPORATIVE POWER.
1 lb. of coke evaporated 9 lbs. of water.*
2 lb. of coal „ 9 „
3 lb. of slack „ 4 „
4 lb. of oak (dry) „ 4| „
5 lb. of piue ,, 2 j „
Coal loses about Ird of its weight in coking, but
increases in bulk ^th.
(Stationary expansive condensing- engines use from
4 to 7 lbs. of coal per indicated horse-power per
hour. Compound engines 1 f to 3 lbs.
Locomotives (passenger) from 20 to 30 lbs. per train
mile.
„ (heavy goods) „ 40 to 55 lbs. „
Wood-burning locomotives will run 24 miles with
1 cord of wood.
A cord of wood = 4 feet x 4 feet x 8 feet.
Navy allowance of stowage of coal = 2700 lbs.;
48 cube feet per ton. The bulk of wood is
about 6 times as much as an equivalent of coal.
An average of 27 kinds of Coal gave about 40g
cubic feet per top. .
* Feed-water supplied at 212° Fahr.