King George III's model carriage wheel, one of fourteen model carriage wheels, by George Adams, Fleet Street, City of London, England, 1762. The wheels were used with the model carriage body which forms part of the inclined horse-way, apparatus made by George Adams for King George III, to imitate the motion of carts and carriages bearing various weights on roads of various inclines. A hay cart was placed on a cobbled 'horse-way', which has a channel cut to imitate a rut. The inclination of the horse-way could be varied, as could the diameter of the wheels and the weight in the cart. The weight needed to keep the cart stationary was a measure of the efficiency of the wheels.