By the time Isaac Fenn was granted a patent, in 1765, for his distance-measuring hodometer, the device had existed, in various forms and with various names, for centuries. In Roman times it was called an odometer and comprised little more than a wheel that could be pushed along, coupled to a mechanical system for counting the number of revolutions the wheel made, and thus the distance it had traveled.
The eighteenth and nineteenth century saw the mapping of India and the division of vast tracts of land into farms in regions such as the United States and Australia. Reasonably accurate surveying and distance measurement became important. The surveyor's perambulator wheel (the "waywiser" or trundle wheel) was in everyday use. The accuracy of this device was good on a smooth surface such as a pavement or macadamed road. On rough terrain, such as farmland, wheel bounce and slippage became a problem and .surveyors had to apply a series of corrections to the readings. For very accurate work, the surveyor had to resort to a tape or chain measure.
A typical eighteenth-century waywiser would have a wheel diameter of around inches (80 cm), equating to a circumference of around feet (2.5 m). This meant that two revolutions of the wheel would equate to one pole (an old English measure of length and area). A central dial with two hands, much like a clock, was attached to the unit. The bigger hand made one sweep every 320 poles—this marking 1 mile (1.6 km). The shorter hand indicated the total number of miles traversed.
Today, professional trundle wheels are extremely accurate and are likely to sport an LCD display and onboard digital storage/manipulation of data.
