Vernier, << VUR nee uhr, >> is an instrument used in measuring lengths and angles. It is named for Pierre Vernier, a French mathematician who invented it in the 1600’s.
The most common vernier has a short, graduated scale, or “ruler,” which slides along a longer scale. The subdivisions on the short rule are nine-tenths as long as the subdivisions on the long scale. Nine small divisions on the large scale are equal to 10 on the small scale.
In using the vernier, the large scale is laid along the material to be measured, a small pipe, for example. The small scale is slid until it reaches the end of the pipe. Now we check to see which of its divisions lines up with one of the divisions on the large scale. Suppose the 5, or fifth division from the zero end of the small scale, lines up with 25 on the large scale. Since each division on the small scale is one-tenth smaller than the large divisions, five divisions are equal to only four and one-half on the large scale. Therefore, the end of the small scale rests at 25 – 4.5, or 20.5 on the large scale.
Engineers often use calipers with a vernier attachment (see Caliper ). Some read to 1/1000 inch (0.0254 millimeter) without a magnifier. The caliper’s beam is divided into inches and tenths, and each tenth is divided into fourths. The vernier is divided into 25 parts. The beam may be divided into fiftieths of an inch. The vernier has 20 divisions to each of its 19.
