Accession No

1881

Brief Description

6-inch gauging slide rule, Verie pattern, by E. Roberts, 4/4 18th C

Origin

Dove Court; Old Jewry; London; England

Maker

Roberts. Edward

Class

calculating

Earliest Date

1775

Latest Date

1800

Inscription Date

Material

wood (boxwood); metal (brass)

Dimensions

length 152mm; breadth 23mm; thickness 21mm

Special Collection

Provenance

Purchased from Harriet Wynter, 352 Kings Road, Chelsea, London, SW3 5UU, in 23/01/1974.

Inscription

‘* EDWD. ROBERTS Maker in Dove Court Old Jewry LONDON *’ (under slide on first face)

Description Notes

Boxwood six-inch Verie pattern gauger’s rule.
First face: single log scale divided 1 - 10, marked ‘A’ on stock and ‘B’ on slider, numbered by 1, 1 - 2 subdivided to 0.02, 2 - 5 subdivided to 0.05, 5 - 10 subdivided to 0.1; brass gauge points let in on stock at ‘MB’ (malt bushel) and ‘A’ (ale gallon), and on slider at ‘W’ (wine gallon). Lower part of stock has inverted scale marked ‘M:D’ (malt depth) divided [2.15] - [21.5], numbered 3, 4...10, 2[0]; 2.15 - 5 subdivided to 0.05, 5 - 10 subdivided to 0.1, 10 - 20 subdivided to 0.2, 20 - 21.5 subdivided to 0.5. Reverse of slide carries table of gauge points.
Second face: on the stock a single log scale divided 1 - 10, marked ‘D’, broken at 3.2 on either side of the slide, numbered by 1 (and also at 3.2), 1 - 2 subdivided to 0.01, 2 - 3 subdivided to 0.02, 3 - 10 subdivided to 0.05; brass gauge points let in at ‘WG’ (wine gallon), ‘AG’ (ale gallon), ‘MS’ (square malt bushel) and ‘MR’ (round malt bushel). Slide has single log scale divided 1 - [9.5], numbered by 1, 1 - 2 subdivided to 0.01, 2 - 5 subdivided to 0.05, 5 - 9.5 subdivided to 0.1. Verso of slide has table of gauge points.
First side: single log scale marked ‘Seg.Ly’ and ‘SL’, divided [0.1] - 100, broken at 4, numbered 1, 2, 3...10, 20, 30...100; 0.1 - 10 subdivided to 0.1, 10 - 100 subdivided to 1. On the slide a single log scale marked ‘C’ divided 1 - 10, numbered by 1, 1 - 2 subdivided to 0.01, 2 - 5 subdivided to 0.05, 5 - 10 subdivided to 0.1. Reverse of slide has table of conversion factors.
Second side: double log scale marked ‘Seg.St’ and ‘SS’, divided [0.8] - 100, broken at 8, numbered 1, 2, 3...10, 20, 30...100; 0.8 - 5 subdivided to 0.1, 5 - 10 subdivided to 0.2, 10 - 100 subdivided to 1. Slide has log scale marked ‘C’ divided 1 - 9, numbered by 1; 1 - 2 subdivided to 0.01, 2 - 5 subdivided to 0.05, 5 - 9 subdivided to 0.1. Reverse of slide has table of conversion factors.

Condition fair (one slide is very stiff and instrument is marked in various places); 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:39567