282 MOTIVE POWER EMPLOYED

fifty-four successive weeks, and, in that time,exclusive of Sundays, the engine, from want ofgoods to convey, was at least twenty days oil'work ; so that, in 304 days, the performancewas 446.815 tons conveyed one mile, or 1470tons one mile each day ; on a stage, only2541 yards. This engine had 3-feet wheels,which were calculated for a rate of about fourmiles and a half an hour ; with larger wheels,and where the distance to be traversed isgreater, the difference of effective speed be-tween horses and loco-motive engines, willbe correspondingly increased. In the worstcases, therefore, the relative performances,when the speed is the same as that of horses,will be represented by column 6, and, whenthe distance and nature of the work is such,that these engines can accomplish an averagerate of speed equal to six miles an hour,then the relative performances in the time-column 10, will bo represented by column13, when they will attain their maximumeffect. The range of their utility will there-fore lay between those two results, and, asthe distance and nature of the work permitthem to approximate towards either of them,their utility will assume the one character orthe other. The least performance of a loco-