Accession No

1874

Brief Description

slide rule, excise / gauging, by Dring and Fage, English, 19th Century

Origin

England; London

Maker

Dring and Fage

Class

calculating

Earliest Date

1800

Latest Date

1900

Inscription Date

Material

wood (boxwood); metal (brass)

Dimensions

length 1142mm; breadth 48mm; thickness 79mm

Special Collection

Provenance

Purchased from Peter Delehar, 146 Portobello Road, London in 31/10/1973.

Inscription

‘DRING & FAGE LONDON MAKERS TO THE CUSTOMS & EXCISE’ (reverse)

Description Notes

Slide rule, excise / gauging, by Dring and Fage, English, C19th.

Boxwood slide rule bound in brass with one slide. Brass holder for moving slide and brass holder at one end of stock.
Obverse: upper part of stock: logarithmic scale divided [17] - 300, numbered 18, 19, 20...60, 65, 70, 75...100, 110, 120...300; 17 - 60 subdivided to 0.25 and to 0.02, 60 - 80 subdivided to 0.25, 80 - 100 subdivided to 0.5, 100 - 300 subdivided to 1. Lower part of stock has inch scale divided [45] - [1], numbered by 1, subdivided to 0.1. Slide has four scales. Logarithmic scale divided [14] - 64, numbered by 1, subdivided to 0.1. Continuation of inch scale divided [45] - 76, numbered by 1, subdivided to 0.1. Also a foot scale divided [12] - [0], numbered by 1, subdivided to 0.1; and another equal scale marked ‘SPHD’ divided 8 - [0], numbered by 1, subdivided to 0.1.
Reverse: three logarithmic scales, ‘A’ on stock and ‘B’ and ‘C’ on slide. ‘A’ divided 10 - 1000, numbered 10, 11, 12...50, 5, 60...100, 110, 120...200, 250, 300...1000; 10 - 80 subdivided to 0.25, 80 - 200 subdivided to 1, 200 - 400 subdivided to 2, 400 - 1000 subdivided to 5. ‘B’ divided 10 - 1000, numbered 10, 11, 12...50, 55, 60...150, 160, 170...500, 550, 600...1000; 10 - 40 subdivided to 0.2, 40 - 150 subdivided to 0.5, 150 - 200 subdivided to 1, 200 - 400 subdivided to 2, 400 - 1000 subdivided to 5. ‘C’ divided 1 - 100, numbered 1, 1.1, 1.2...3, 3.5, 4. 4.5...10, 11, 12...20, 25, 30, 35...100; 1 - 20 subdivided to 0.1, 20 - 40 subdivided to 0.2, 40 - 100 subdivided to 0.5. Lower part of stock has logarithmic scale marked ‘Segt Ly’ divided 0.1 - 100, numbered 0.1, 0.2, 0.3...1, 2, 3...30, 35, 40, 45...100; 0.1 - 10 subdivided to 0.1, 10 - 20 subdivided to 0., 20 - 50 subdivided to 0.5, 50 - 100 subdivided to 1.

Condition good; 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:42155