screw is turned by a treadle, the connecting mechanism being such that it may be adjusted to turn a whole revolution or any desired part of a revolution by a movement of the treadle.
For this invention he received a reward of £ 600 from the British government, on condition of executing the divisions on the instruments of other makers at a fixed price for each instrument.
An instrument of this kind, by Troughton & Sims, is in the Coast Survey Building, Capitol Hill, Washington.
Hindley, 1740, had invented a dividing-engine, upon which this of Troughton is said to have been based.
It also served for cutting the teeth for clockwheels.
See also dividing-engine.
In addition to original graduation by the beam compass and engine, the dividing of a scale or a circle is performed (and this is the most common practice with regard to ordinary instruments) by means of a dividing-plate, which is itself originally graduated with great care.
This consists of a circle carrying a pivoted