vernier

A small, movable auxiliary graduated scale attached parallel to a main graduated scale, calibrated to indicate fractional parts of the subdivisions of the larger scale, and used on certain precision instruments to increase accuracy in measurement.

An auxiliary device designed to facilitate fine adjustments or measurements on precision instruments.

Of, relating to, or having a vernier.

A small movable scale, running parallel with the fixed scale of a sextant. theodolite, barometer, or other graduated instrument, and used for measuring a fractional part of one of the equal divisions on the graduated fixed scale or arc.

A short scale made to slide along the divisions of a graduated instrument, as the limb of a sextant, or the scale of a barometer, for indicating parts of divisions. It is so graduated that a certain convenient number of its divisions are just equal to a certain number, either one less or one more, of the divisions of the instrument, so that parts of a division are determined by observing what line on the vernier coincides with a line on the instrument.

a gauge with a graduated bar and a sliding jaw bearing a vernier, used for accurate measurements.

a surveyor’s compass with a vernier for the accurate adjustment of the zero point in accordance with magnetic variation.

a surveyor’s transit instrument with a vernier compass.

A secondary scale with finer graduations than the primary scale of a measuring device; the vernier measures between graduations of the larger scale.