Vernier scale

de:Nonius fr:Vernier (mesure) ja:ノギス nl:nonius A vernier scale lets one read more precisely from a measurement scale. It was invented in 1631 by the French mathematician Pierre Vernier (1580-1637).

A vernier has two scales, an indicating scale and a data scale. These move past each other, usually on a slide. When the measurement is taken, the zero point of the indicating scale lies at the true datum of the measurement. This will usually be between two gradations of the data scale and the indicator scale is used to ascertain where between the two it lies.

The vernier's indicating scale has a series of gradations at a slighty different spacing to those on the data scale. One of these will align exactly with a gradation on the data scale. The indicator scale number at this aligned point will be the extra digit of the measurement.

In instruments using decimal measure the indicating scale would have nine gradations covering the same length as the ten on the data scale. Only one will align with a mark on the data scale and it is the number of this one which indicates the next decimal place.

Verniers are common on sextants, machinists' measuring tools (all sorts, but especially calipers and micrometers) and on slide rules.

For the village in the Canton of Geneva, Switzerland, see: Vernier GE.