View source for Nonius (nonfiction)

A '''nonius''' is a measuring tool used in navigation and astronomy named in honor of its inventor, [[Pedro Nunes (nonfiction)|Pedro Nunes]] (Latin: Petrus Nonius), a Portuguese author, mathematician and navigator. The nonius was created in 1542 as a system for taking finer measurements on circular instruments such as the astrolabe.

The nonius was used to improve the astrolabe's accuracy. This consisted of a number of concentric circles traced on an instrument and dividing each successive one with one fewer divisions than the adjacent outer circle. On a standard scale of 90 degrees, there are an additional 44-45 concentric circles with each divided into a specific unit size such that a scale unit on position ''n'' had an arc of 90/''n'' degrees. Thus, the outermost quadrant would comprise 90° in 90 equal divisions, the next inner would have 89 divisions, the next 88 and so on. When an angle was measured, the circle and the division on which the [[Alidade (nonfiction)|alidade]] fell was noted. A table was then consulted to provide the exact measure.

The astronomer [[Tycho Brahe (nonfiction)|Tycho Brahe]] applied the nonius to the astronomic quadrant.

The system was eventually adapted into the vernier scale in 1631 by the French mathematician [[Pierre Vernier (nonfiction)|Pierre Vernier]].

In numerically controlled machines, the nonius is part of several absolute encoders that measure linear or rotational displacements.

== In the News ==

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== Fiction cross-reference ==

* [[Gnomon algorithm]]
* [[Mathematics]]

== Nonfiction cross-reference ==

* [[Alidade (nonfiction)]]
* [[Mathematics (nonfiction)]]

External links:

* [https://en.wikipedia.org/wiki/Nonius_(device) Nonius (device)] @ Wikipedia


[[Category:Nonfiction (nonfiction)]]
[[Category:Computation (nonfiction)]]
[[Category:Machines (nonfiction)]]