On metal rails a horse can draw: One and two-thirds times as much as on asphalt pavement; three and one-third time3 as much as on good Belgian blocks; five times as much as on ordinary Belgian blocks; seven times as much as on good cobble-stone; thirteen times as much as on ordinary cobble-stone; twenty times as much as on an earth road; and forty times us much as on sand.

A modern compilation of engineering maxims states that a horse can drag, as compared with what he can carry on his back, in the following proportions: On the worst earthern road, three times more; on a good macadamized road, nine; on plank, twenty-five; on a stone trackway, thirty-three; and on a good railway, fifty-four times as much.