"vernier scale." YourDictionary, n.d. Web. 20 January 2019. <https://www.yourdictionary.com/vernier-scale>.
vernier scale. (n.d.). Retrieved January 20th, 2019, from https://www.yourdictionary.com/vernier-scale
A small, movable auxiliary graduated scale attached parallel to a main graduated scale and calibrated to indicate fractional parts of the subdivisions of the larger scale. Vernier scales are used on certain precision instruments to increase accuracy in measurement.