Accession No

0189

Brief Description

Boxwood slide rule, by Robert Brettell Bate, English, 1/2 19th C

Origin

London; England

Maker

Robert Brettell Bate

Class

calculating

Earliest Date

1803

Latest Date

1847

Inscription Date

Material

wood (boxwood); metal (brass)

Dimensions

length 940mm; width 51mm; thickness 10mm

Special Collection

Provenance

Inscription

‘BATE LONDON’ (obverse)

Description Notes

Boxwood slide rule, by Robert Brettell Bate, English, 1/2 19th C.

Obverse: four identical double radius log scales, two on stock and two on slide, each marked ‘NUM’, divided 1 - 100, numbered 1, [1.]1, [1.]2...10, 11, 12...100.
Reverse: upper part of stock has scale marked ‘plus’ and ‘sines’ divided [0.6] - 250 and back to 29000, numbered 1, 2...20, 25, 5[0], 10[0],...50[0], 10[00]...50[00], 10[000], 11[000]...29[000]. Slide carries scale of sines divided [0.6] - 90, numbered 1, 2...60, 62...70, 80, 90 (also numbered in reverse for cosines); also scale of tangents, marked ‘tan’, divided [0.6] - [45], numbered by 1. Lower part of stock has scale marked ‘sines’ and ‘minus’, divided as on the upper part of the stock.
One edge has inch scale divided [0] - 36, numbered by 1, subdivided to 0.1.

Condition good; complete.

References

Events

Description
This boxwood slide-rule was made by the London scientific instrument maker Robert Brettell Bate (1782–1847). Developed during the seventeenth century, the modern slide rule is based upon the design by William Oughtred (circa 1630). It is one of many calculation devices that is based on the logarithmic scale, a calculation method invented in 1614 by John Napier.

Before the rise of the pocket electronic calculator in the 1970s, the slide rule was the most common tool for calculation used in science and engineering. It was used for multiplication and division, and in some cases also for ‘scientific’ functions like trigonometry, roots and logs, but not usually for addition and subtraction.

A logarithm transforms the operations of multiplication and division to addition and subtraction according to the rules log(xy) = log(x) + log(y) and log(x/y) = log(x) - log(y). The slide rule places movable logarithmic scales side by side so that the logarithms of two numbers can be easily added or subtracted from one another. This much simplifies the alternative process of looking up logs in a table, thus greatly simplifying otherwise challenging multiplications and divisions.

For more on Bate’s life and works, see Wh.6262.

FM:42277