WAGON, a vehicle for the conveyance of goods or passengers, is mounted on four wheels, but varies considerably in the construction of its other parts, according to the species of the traffic in which it is to be employed. Since the wagon has four wheels, it is quite unnecessary that any part of the weight should be sustained on the shafts, and accordingly these latter are hinged to the fore-part of the frame, so as to be raised or let down at pleasure. Wagons being generally drawn by two horses abreast, two pair of shafts are employed; and when three horses are yoked abreast, the center one is the shaft horse, the right and left " wheelers" are yoked by traces to the wagon-frame; and each of the latter is attached by a chain from its collar to a shaft, so as to preserve the parallelism of its action. Most wagons are set on springs, on account of the weight of the vehicle, and the absence of the steadying weight of the horse, owing to the shafts not being immovably attached to the frame. For facility in turning, the fore wheels are occasionally smaller than the hind ones; and in addition, the fore axle of the lighter kinds of wagon is attached to the body of the wagon by a swivel-joint, the shafts or pole being in this case attached to the fore axle; but the diminution of the size of the wheels is open to grave objection, on account of the greater friction. It being almost impossi ble for the beasts of draught to control and subdue the momentum of a heavily-loaded wagon descending a slope, it is necessary to employ a drag of some sort; the rudest forms of which are a thick cylinder of tough wood inserted between two spokes of the wagon which, being carried upward in the wheel's revolution, is " jammed" against the under side of the wagon-frame, and stops the wheel's rotation; and the which was merely a chain firmly fastened at one end to the wagon-frame between a fore and a hind wheel, and furnished at the other end with a large hook, to hold the tire of the hind wheel; the method of chaining the fore and together was also employed.
But in the bettei class of wagons, the shoe and break (see DRAG) are now employed. The various forms of wagon in common use are the brewer's dray, the railway lorry, the agricultural wain (in common use in England and on the continent), and the bullock cart of s. Africa. The comparative merits of a vehicle in which the horse has merely to ,draw, and one, as the cart, in which he has to carry' as well as draw, have often been discussed, though never sufficiently tested; but it seems to be generally believed that, despite the distress arising from his confined position7in the comparatively immovable shafts of a cart, a horse can transport a greater weight to a moderate distance by the same exertion of muscular force in a cart than m a wagon.