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The type of scale used on sextants to interpolate tenths of minutes on the micrometer drum. The vernier scale lies adjacent to the micrometer scale, with 9 units on the micrometer scale divided into 10 units on the vernier scale. With this clever arrangement, you read the proper fractional part of the minutes from the vernier scale by noting which unit of the vernier scale most closely aligns with any unit of the micrometer scale. The procedures with examples and graphics are in Chapter 2 of our Cel Nav Course.

Technically speaking, "vernier scale" may be redundant, since the word "vernier" has come to mean a type of scale, but this is not an important point, except we do not wish to minimize the great contribution of Pierre Vernier (1580 - 1637) and others who developed the idea. It was a crucial component of the Industrial Revolution.

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