The principles of draught are in these works first set out with reference to the sledge. We are told that, from long experience, it is found if the traces are attached to the sledge so high that the trace is horizontal or parallel with the ground, and the sledge meets with any obstacle in a rough track, the runners will bite into the obstruction so as almost to stop the team, but if the traces are fastened lower, so as to form a straight line from the horse’s collar to the hind end of the runners of the sledge, then they will lift, as it were, at the obstacle, and glide easily over it. This theory appears quite correct. It is more readily discovered in a sledge than in a carriage upon wheels, but the principle is the same in each. Again, if the runners project in advance of the sledge it follows easier than if they begin to turn upwards beneath the weight of the sledge. This in wheel carriages is the same as if the weight of the carriage were mostly on the low front wheel, instead of upon the higher hind wheels. In the New York magazine we are asked, “Why will a team haul a load on a vehicle of four wheels easier than the same load upon two wheels?” and “Why will a team haul a load in a circle, which they cannot move straightforward?” The obvious answer is, that the same load presses on the ground in two places heavier than it does upon four places, and, secondly, that when moving in a circle the obstacles are less felt by the inner wheels than by the outer. But the magazine gives further ingenious reasons. When a load is resting upon a two-wheeled vehicle it is very seldom placed so as to balance just right. If correct for level ground, as soon as it ascends a hill, or descends, the balance is unsettled. When the wheels come to a hole, or a big stone, all the load must be raised with two wheels and only half when on four wheels. Again, an uneven road twists the horse that is between the shafts from side to side, when the load is on two wheels, more than when, on four wheels, the fore-carriage rotates on the perch-box. Again, on an incline the four-wheeler moves by its own gravity, whilst the two-wheel gives additional weight at once on the horse’s back. To the second question the magazine writer remarks that an experienced driver takes his load up hill zigzag, and not straight, and what is lost in time is gained in power. On the question of the height of the splinter-bar and whipple-trees, he gives his experience of twenty years that they should be, as a rule, a foot below the point of traction at the horse’s collar. He explains the advantage of splinters (like our leading-bars) for all the horses of a team, and not only the leaders, to be this--that if one horse is lazy, then the others draw their bars forward, and, consequently, his bar going back brings his traces tight again.