These weights include the carriages. It is usual, however, in heavy carriages, to reckon all their weight exceeding twelve cwt. as part of the load.
The most useful mode of applying a horse’s power is in draught, and the worst is in carrying a load. This is owing to the structure of the animal. It has been found that three men, carrying each 100 lb., will ascend a hill with greater rapidity than one horse carrying 300 lb. When a horse has a large draught in a waggon, however, it is found useful to load his back to a certain extent, this prevents him from inclining so much forward as he would otherwise do, and consequently frees him from the fatigue of great muscular action. The best disposition of the traces in draught is when they are perpendicular to the collar; when the horse stands at ease, the traces are then inclined to the horizon, at an angle of about 15°; but when he leans forward to draw, the traces should then become nearly parallel to the road. The most proper inclination, however, is determined from the relation which subsists between the friction, and the pressure, in every particular case.
When a horse is employed in moving a machine, by travelling in a circular path, the diameter of the path ought not to be less than twenty-five or thirty feet, and in most cases forty feet should be preferred: at all events, it must not be less than eighteen feet.
The following table shows the maximum quantity of labour, which a horse of average strength is capable of performing at different velocities, on canals, railways, and turnpike roads; but in comparing this table with practice at the higher velocities, it is reckoned necessary to add one-third more than the useful effect for the total mass moved.
| Velocities per hour. | Day’s work. | Force of traction. | Useful effect per Day for a distance of one Mile on a | |||
| Canal. | Level railway. | Level road. | ||||
| Miles. | Hours. | lb. | Tons. | Tons. | Tons. | |
| 2½ | 11·5 | } | { | 520 | 115 | 14 |
| 3 | 8· | } | { | 243 | 92 | 12 |
| 3½ | 5·9 | } | { | 153 | 82 | 10 |
| 4 | 4·5 | } | { | 102 | 72 | 9 |
| 5 | 2·9 | } | 83⅓ { | 52 | 57 | 7·2 |
| 6 | 2· | } | { | 30 | 48 | 6 |
| 7 | 1·5 | } | { | 19 | 41 | 5·1 |
| 8 | 1·8 | } | { | 12·8 | 36 | 4·5 |
| 9 | ·9 | } | { | 9 | 32 | 4 |
| 10 | ·75 | } | { | 6·6 | 28·8 | 3·6 |
Result of experiments with a light four-wheeled cart, weighing with its load 1000 lb., drawn upon different sorts of roads, (12½ lb. having been deducted from the force of traction for the friction at the axles, which were of wood).
| Turnpike-road, | hard, dry | 18 | } Force of traction |
| Do. | dirty | 26½ | } required to move the |
| Do. | new gravelled | 130½ | } carriage, independent of |
| Loose sandy road | 191½ | } the friction at the axles. | |
| Note.—An ox can draw about 4 cwt., and a pair of oxen 9 cwt., on a level road. | |||
MANAGEMENT OF DRAUGHT HORSES.
Whatever the difficulties of a road or ground may be, ten horses are as many as can be harnessed with effect to one carriage. It is difficult for a greater number to act at the same instant, even if the pull be straight.