The Jones Counter is a mechanical device used for measuring distances traveled by a bicycle. It was invented by Roy Jones, an American engineer and cyclist, in the 1930s. Jones was an avid cyclist who became frustrated with the lack of accurate distance measuring devices for bicycles. He developed the Jones Counter as a solution to this problem. The device consists of a series of gears and dials that are attached to the bicycle's front wheel. As the wheel rotates, the gears and dials register the distance traveled. The Jones Counter has been widely used by bicycle touring enthusiasts, race organizers, and transportation planners to measure distances for planning and mapping purposes.
I then tried Microsoft's Bing:
The Jones Counter is a device fitted to the front wheel of a bicycle that counts the revolutions of the wheel. It was invented in 1971 by Alan Jones in order to measure the length of road running race courses1. Almost all road running courses in the world are measured with this device1. The Jones Counter has been used to measure all Olympic Marathon courses since the 1976 Montreal Olympics except for the 1980 Moscow Olympics1.