# 1960s Calculator

The mechanical calculating machine was widely used in the first half of the 20^{th} century, in office calculations and in scientific applications. The Warwick School Mathematics Department retained the machine used by Professor Watson to calculate the values of Bessel Functions.

Addition, subtraction, multiplication and division were all possible to a high degree of accuracy, though the result did not appear instantly. A considerable amount of handle-turning and carriage-shifting was involved in a big long division calculation, but a skilled operator could carry out such tasks surprisingly quickly. I can remember their use in my A-level exams in 1970, where the numerical methods questions could be answered with slide rule, logarithm tables or mechanical calculator, a different degree of accuracy being required for each option.

They were heavy and far from quiet, with a bell sounding to assist the process of division without looking at the machine, when the handle was turned too many times. Pupils quickly discovered this and the bells could be a nuisance in lessons.

We retained the machines well into the 1970s because it was felt that they were useful for showing that division was merely an efficient process of continued subtraction.

Peter O’Grady, WS Staff 1975-