280

MOTIVE TOWER EMPLOYED

Rail-road: a loco-motive engine we have found travels atthis rate with 800 cwt.; therefore, if 270 cwt. required fourhorses, 800 cwt. will require twelve horses, so that we findthe united effort of twelve horses continually required toperform the work of one loco-motive engine, both travellingat the same rate of speed, and that speed six miles anhour.

, Suppose the quantity conveyed amount toforty tons, four horses travelling at the rate oftwo miles an hour will, in ten hours, convey thisweight twenty miles ; if a loco-motive engine beemployed, and travelling at the same speed, itwill in the same time perform a similar quan-tity of work, which will be that of four horses ;but, supposing that instead of the loco-motiveengine travelling two miles an hour, that itaverages a velocity of four miles per hour, thenin ten hours it will travel forty miles, and con-vey forty tons that distance, which is equal tothe performance of eight hours, travelling atthe rate of two miles an hour. And again, byfurther increasing the velocity of the loco-mo-tive engine, until it accomplishes a rate of sixmiles an hour ; then, in ten hours, it will travelsixty miles, and convey forty tons that dis-tance, which would require the united effort oftwelve horses.

It is, however, only on long stages where