Vernier scale

A graduated auxiliary scale that measures fractions of the smallest divisions on a fixed scale by comparing the alignment of its marks.

Least count: The smallest measurement increment an instrument can resolve. A vernier’s least count is set by the difference between its scale divisions.
Graduation: A mark or interval on a measuring scale used to indicate quantity. Vernier scales refine readings by comparing two sets of graduations.
Vernier caliper: A length-measuring instrument with sliding jaws and a vernier scale. It uses the vernier principle to measure external, internal, and depth dimensions.
Nonius scale: A scale arrangement attributed to Pedro Nunes for reading fractions of a graduated scale. It is a historical predecessor whose name is sometimes used loosely for vernier scales.
Main scale: The primary graduated scale on a measuring instrument. The vernier adds fractional readings to this fixed scale’s graduations.
Length measurement: The determination of distance between two points using a defined unit. A vernier scale is a method for increasing the precision of length measurement.
Micrometer microscope: A microscope fitted with a calibrated movable scale for measuring small distances. A vernier can subdivide its stage’s fixed graduations for finer position readings.
Micrometer screw gauge: A measuring instrument that converts screw rotation into precise linear displacement. It resolves small lengths through screw pitch rather than comparing aligned scale marks.
Vernier constant: The difference between one main-scale division and one vernier-scale division. This interval determines how much each successive alignment changes the reading.
Ratio: A comparison of two quantities expressed by division. The scale’s division counts are chosen so their interval difference is measurable.

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AlidadeRelated: Many alidades use it to read angles more finely than the main graduation permits.