Circular slide rule performing trigonometrical calculations - has coloured scales, square grid and pointers providing variety of mathematical functions

摘要

A slide-rule is used for the demonstration of mathematical functions. It consists of a square card carrying a set of circular scales and a cursor with a cruciform pointer arrangement. The slide rule may perform calculations in elementary trigonometry. The function F(X):Y = aX + b may be studied, with the function F(X) : y = c. In addition to the circular scales the slide rule card carries a rectangular grid which is of use in the trigonometrical calculations. The various scales and pointers are colour coded for ease of identification.