252

MOTIVE POWER EMPLOYED

whole distance from the commencement to theend of the stage ; the other was, that part ofthe stage which the engine passed over, whenthe regular velocity was acquired, and before itwas again diminished at the end of the stage,to stop the train; the time given iu the Tablewas that which trauspired while the engine waspassing over that space, while the velocity wasuniform ; and may, therefore, be taken as ameasure of speed.

Experiments XXIX and XXX were made,to ascertain the effect with wheels of dif-ferent diameters. The engine was the same ineach experiment; the only alteration made,was taking the 3-feet wheels from off the axlesof the engine, and replacing them with wheels4 feet diameter. The stage was the same, andevery care was taken to make the experimentan accurate comparison of their relative effects.

Consumption of coals and weight propelledremained the same.

r 3-l'ect wheels 1 traversed the (36 milesNo. I. Engine ) > respective <

( 4 -feet wheels ) distances of (48.8 miles;

Whence we find, that, with a given quantity offuel, the distance traversed by the engine, withdifferent-shed wheels, is in the ratio of the dia-meter of these wheels, when the load is the samein both cases.

The consumption of fuel, when every cir-