vernier

vernier (vûr`nēr), auxiliary scale, either straight or an arc of a circle, designed to slide along a fixed scale. Its unit divisions, usually smaller than those on the fixed scale, permit a far more precise reading. The vernier is attached to the scales of instruments employed for very accurate linear or angular measurements; these include the transit, sextant, barometer, compass, and caliper. It was devised by a French mathematician, Pierre Vernier, who described it in his Construction, usage et propriétés du quadrant nouveau de mathématiques (1631). Certain auxiliary control mechanisms used for fine measurements or adjustments are often called verniers.

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vernier

 or vernier caliper

Instrument for making very accurate linear or angular measurements. Introduced in 1631 by Pierre Vernier (c. 1580–1637), it uses two graduated scales: a main scale similar to that on a ruler, and a specially graduated scale, the vernier, that slides parallel to the main scale and enables readings to be made to a fraction of a division on the main scale.

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vernier

1. a small movable scale running parallel to the main graduated scale in certain measuring instruments, such as theodolites, used to obtain a fractional reading of one of the divisions on the main scale

2. an auxiliary device for making a fine adjustment to an instrument, usually by means of a fine screw thread

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vernier [′vər·nē·ər]

(engineering)

A short, auxiliary scale which slides along the main instrument scale to permit accurate fractional reading of the least main division of the main scale.