ON IUIL-K0AD5.

279

scarcely any limit, as our numerous manufacto-ries evince the difficulty of conceiving-to whatextent it may be carried. The result in theTable may be brought into very familiar com-parison with the performance of horses in thestage-coaches upon the turnpike-roads. Thedifference of resistance between carriages movedupon the common roads, and upon a Rail-way,is from observation found to be about as 7.5 :1 ;a horse will, therefore, draw ten tons upon aRail-way with the same ease that he can draw27 cwt. upon the common roads, travelling atthe rate of two or two and a half miles anhour. The resistance, or the energy of thepower which the horse exerts in both cases,will therefore be the same, and be equal to1121bs.

Let that pace be quickened to 6 miles an hour, and by theTable we should have for the energy of his power 37i lbs.,and in the case of the stage-coaches with 4 horses, 37 i X 4= 150 lbs. nearly, as the united effort of the 4 horses.Then, as 112 lbs. : 150 lbs. ‘27 cwt.: 3Gcwt., the load,which, according to the Table, we should have as the per-formance of 4 horses upon the common roads, conveyed20 miles a day. We may now apply this to the lcco-mo-tive engine; suppose the stage 20 miles, and that this is thedistance which 4 horses will daily convey, a stage-coach,weighing 36 cwt. upon the common road, or 36 X 7.5 =270 cwt., travelling at the rate of 6 miles an hour upon a