Accession No

5822

Brief Description

slide rule, unsigned, English, second half of the 18th Century

Origin

Maker

unknown

Class

calculating

Earliest Date

1750

Latest Date

1800

Inscription Date

Material

wood (boxwood); metal (brass)

Dimensions

length 330mm

Special Collection

Provenance

Purchased from Tesseract, Box 151, Hastings-on-Hudson, New York 10706, U.S.A., on or before 21/12/2000. Item No. 68 from Catalogue 68 Winter 2000/2001.

Inscription

Description Notes

slide rule, English, second half of the 18th century, unsigned. Brass bound boxwood with inset brass points. The rule incorporates two sliders each insertable for use on any of its four sides. There are sliding scales for the surfaces and volumes of complex shapes including Speroid Standing, Seg. parabolick Spind, Perip. Elipsis. Trigonometric and logarithmic scales are present (Tan, Sin. Chord, Square, Root, Cube etc.). One of the wide sides without slider is divided with a further eight geometric and trigonometric scales; the opposite side with fourteen Gunter's rule scales of navigation and sundial construction, including "Latitude, Hours, Meridians, Lea"

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:46227