A mathematical instrument is a tool or device used in the study or practice of
mathematics. In
geometry, construction of various proofs was done using only a
compass and
straightedge; arguments in these proofs relied only on idealized properties of these instruments and literal construction was regarded as only an approximation. In
applied mathematics, mathematical instruments were used for measuring angles and distances, in
astronomy,
navigation,
surveying and in the measurement of time.^{
[1]}

Overview

Instruments such as the
astrolabe, the
quadrant, and others were used to measure and accurately record the relative positions and movements of planets and other celestial objects. The
sextant and other related instruments were essential for navigation at sea.

The
Oxford Set of Mathematical Instruments is a set of instruments used by generations of school children in the United Kingdom and around the world in mathematics and geometry lessons. It includes two set squares, a 180° protractor, a 15 cm ruler, a metal compass, a 9 cm pencil, a pencil sharpener, an eraser and a 10mm stencil.

^Gerard L'Estrange Turner Scientific Instruments, 1500-1900: An Introduction ( University of California Press, 1998)
ISBN0520217284 page 8

External reading

J. L. Heilbron (ed.), The Oxford Companion To the History of Modern Science (Oxford University Press, 2003)
ISBN0195112296, Instruments and Instrument Making, pp. 408–411