"FOWLER TRICYCLE, 1880 U.S.N.M. No. 309257... photograph No. 784-D ; plate 11, b. Patent No. 224165... February 3, 1880, to Francis Fowler... for a tricycle equipped with a ratchet connection in the hub of each driving wheel. The purpose was to enable the outer of the two driving wheels to rotate freely on the crankshaft when the machine was making a sharp turn, thus performing the function of a modern automotive differential unit. This model... is constructed of metal with... wooden grips on the handle bars and leather straps on the pedals of the cranks... The frame consists of a curved bar at the rear, upon which a saddle is located, and a vertical forked frame at the front pivoting in the steering head of the bar. At the top of the fork is a horizontal bracket supporting a rod which serves as the handle bars. This rod is free to be rotated within its supports in the bracket. Rotating the rod tightens a cord running down the curved bar and causes a brake shoe to bear against the single rear wheel mounted at the lower end of the bar. ... An axle is mounted at the bottom of the fork. On each end of the axle is a wheel... Cranks connect the axle and the wheel hubs. Each front-wheel hub incorporates a pair of double-crown, ratchet gears held together by a spring in the hub. Forward movement of the axle drives the wheels, but when the cranking is halted and the axle is stationary the ratchets open and the wheels coast. ...[T]he outer wheel slips when the machine is making a sharp turn. Each intermittent opening of the ratchets would cause the wheels to be forced slightly apart and would occasion considerable wear of the teeth, as well as a clicking noise, deficiencies not found in the Van Anden velocipede, with its pawl-and-ratchet device in the hub of the front wheel."