Accession No

0384

Brief Description

slide rule, 20th Century

Origin

Maker

Class

calculating

Earliest Date

1900

Latest Date

1970

Inscription Date

Material

wood; plastic (ivorine, perspex); metal (white metal); paper (card); hide (leather)

Dimensions

length 520mm; breadth 38mm; thickness 13mm case length 531mm; breadth 46mm; thickness 17mm

Special Collection

Cavendish collection

Provenance

Hutchinson Collection

Inscription

‘D.R.G.M. 41294’ (under slide)

Description Notes

Wooden slide rule faced with ivorine. Perspex cursor bound in white metal.
Obverse: identical double radius log scales on upper part of stock and slide, divided 1 - 10[0], numbered 1, [1.]1...2, 3...2[0], 3[0]...10[0]. Identical single radius log scales on lower part of stock and slide, divided 1 - 10, numbered 1, [1.]1...2, 3...10.
Reverse of slide has scale of tangents, marked ‘T’, divided [35´] - [45˚], numbered 1, 2...20, 25...40. Also scale of sines, marked ‘S’, divided [35´] - [90˚], numbered 1, 2...20, 25...50, 60, 70, 80. Also central scale of equal parts, divided [0] - 1000, numbered by 20, subdivided to 1.
Underneath slide is centimetre scale divided [52] - [104], numbered by 1, subdivided to 0.1.
Bevelled edge has scale of inches, divided 0 - 20, numbered by 1, subdivided to 1/16. Other edge has scale of centimetres divided [0] - [52], numbered by 1, subdivided to 0.1.
Reverse plain.
Card slip case covered with leather.

Condition good (part of ivorine chipped off one edge); complete.

References

Events

Description
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. To multiply, for example, you place the start of the second scale at the log of the first number you are multiplying, then find the log of the second number you are multiplying on the second scale, and see what number it is next to on the first scale.

FM:42516