The driver's seat is fixed in the interior of a wide ring to which are fastened the shafts. This ring revolves, by the aid of three pulleys or small wheels, within the large ring resting on the ground. It will be seen that when the horse is drawing the vehicle, the friction of this large wheel against the ground being greater than that of the concentric one within it, the latter will revolve until the center of gravity of the whole is situated anew in a line vertical to the point at which it bears on the ground. The result of such an arrangement is that the driver rolls on the large wheel just as he would do on the surface of an endless rail. As may be conceived, the tractive stress is, as a consequence, considerably diminished.
There are two side wheels which are connected by a flexible axle to the seat of the carriage, but these have no other purpose than that of preventing the affair from turning to one side or the other.

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