I’M 1

264

MOTIVE POWER EMPLOYED

li.-"

maximum load, for, if any diminution of frictiontakes place in the engine, when employedin dragging a lighter load, the consumptionof fuel will be more than proportionablyreduced; and, though against the effect of theengine, will be the safe side in practice.

The consumption of coals in ExperimentXXXIII. was 587lbs. for conveying 975cwt.of goods, exclusive of the weight of the engineand convoy-carriage, 20020 yards upon a hori-zontal plane.

Reducing this to the consumption per mile, viz.

As 20020 : 1760 :: 587 : 51.55 lbs., the fuel consumedper mile in conveying 975 cwt.; the resistance of 975 cwt., asbefore stated, is 4801bs.and the friction of the engine 384 lbs.;therefore, the quantity of coals consumed, in overcoming aresistance of 480 + 384 = 864 lbs. for a mile is 51.551bs.

Let P — the friction of the engine = 384 lbs.

R = the friction of any number of carriages whichmay be taken as the 200th part of their weight;

Then, as 864 lbs., the friction of the carriages conveyed1 mile, I is to 51.55 lbs. the coals consumed in conveyingthose goods a mile, as per experiment; ” so is P + R, theresistance of any other number of carriages and engine ‘ to

51.56 x R + P

864

the quantity of coals required to convey any given weightof goods, whose friction or resistance is equal to R, thedistance of one mile upon a level Edge-rail-road.

The formula

51.55 X R + P864

will then represent the con-

sumption of coals with any load R, and if by a further