This instrument is constructed on the same principle as a slide rule. The treadwheel was a common method of punishment in 19th century prisons. The left-hand part of this calculator, which is fixed, contains the 'Feet Ascent' and 'Steps per Minute' scales. Prison governors would probably have a set of 'feet ascent 'per prisoner and time of running the wheel per day. They would need to know the proportion of prisoners to be put on at any time or the number of steps per minute required. The instrument can be used in various ways. Any one unknown could be found given the other information. This treadwheel labour calculator was made by R B Bate of London.
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