The Parking Meter: A Coin That Unlocks a Clock

By the 1930s city streets were lined with cars parked all day, and shops lost the customers who could not stop. A parking meter rations the kerb: a coin buys a set time, and a signal shows anyone passing when it has run out. Carl C. Magee of Oklahoma City, assignor to the Dual Parking Meter Company, filed US 2,118,318, *Coin Controlled Parking Meter*, on 13 May 1935; it was granted 24 May 1938. Inside a lockable head on a post, a coin completes the winding mechanism; turning the handle winds a spring; an escapement-governed train runs it down; a signal shows while the time lasts and vanishes when it has elapsed. The last coin shows in a window, and the coins fall into a sealed container so the collections can be checked. Oklahoma City installed Magee's meters in July 1935. This rung designs the gear train and the spring for a one-hour meter and builds a coin-interlocked timer from a wind-up motor.