A waywiser consists of a large wheel that can roll along a level surface, and
a dial that registers the distance traveled. The wheel usually measures 8.25
feet in circumference, such that 2 revolutions are equal to 1 pole. The larger
hand on the dial makes one sweep per mile (320 poles or 8 furlongs). The shorter
hand indicates the number of miles traveled. Waywisers became popular in England
in the 18th century, and were still in use in the United States in the late-19th
century. They were was also known as perambulators.
Ref: Jane Insley, "Odometer," in Robert Bud and Deborah Warner,
eds., Instruments of Science (New York and London, 1998), pp.423–424.