Accession No

3043

Brief Description

slide rule by Tavernier Gravet, 1/2 20th C

Origin

19 Rue Mayet; Paris; France

Maker

Tavernier-Gravet

Class

calculating

Earliest Date

1900

Latest Date

1950

Inscription Date

Material

wood (plywood); glass; metal (white metal); paper (card); hide (leather)

Dimensions

length 282mm; breadth 34mm

Special Collection

Steward collection

Provenance

Collection purchased from member of the Steward family, 1974.

Inscription

‘REGLE - BEGHIN TAVERNIER-GRAVET MDEAILLES D’OR 1878–1889–1900 RUE MAYET 19, PARIS MODELE DEPOSE’ (reverse)

Description Notes

Plywood rule faced with white celluloid. One bevelled edge carrying centimetre scale divided 0 - 25, numbered by 1, subdivided to 0.1. Upper part of stock carries two scales: first divided [5˚ 30´] - 90˚, numbered 6, 7, 8, 9, 10, 15...40, 50...90. Second divided [0.31] - [3.2], numbered by 0.1 up to 2, then 3. This scale also appears on the slide, which carries two further scales both divided 1 - 1[0] but in opposite directions, numbered 1, [1.]1, [1.]2...2, 3...1[0].
Lower part of stock repeats lower scale.
Lower edge of rule carries scale divided 0 - 10, numbered by 1, subdivided to 0.02.
Perspex and white metal cursor.
Reverse carries various formulae and conversion factors.
Leather-covered card slip case.

Condition fair (celluloid coming away in one place); 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:42503