Accession No

5387

Brief Description

slide rule and stylus adder in case, by A. W. Faber, German

Origin

Germany

Maker

A. W. Faber

Class

calculating

Earliest Date

Latest Date

Inscription Date

Material

metal (brass, other); plastic (?celuloid); paper (card); wood

Dimensions

box length 310mm; width 52mm; thickness 22mm

Special Collection

Provenance

Donated in 17/02/1999. Used by Denys Bliss, inventor of the segmented skirt (used in Hovercraft).

Inscription

‘A.W.FABER CASTELL Addiator 1/54A DARMSTADT’ (on rule under slider)
‘A.W.FABER
CASTELL-Addiator DRP
DARMSTADT 1/54A’ (on box)

Description Notes

Card slip case with plasticised green exterior. Wooden slide rule with plastic (celuloid?) scales, single double sided slide, colourless plastic sliding indicator. On the reverse of the rule a brass stylus adder (stylus held in hole in end of rule) labeled ‘SALDO NEG’.

Stock has three log scales- 1-1000, 0.8-120 and 0.9-11 and one marked √1-x2 0.995-0. One edge has sin 5.8-90 and cos 80-0 (in red on same scale) also tan 5.8-45 and cotan 80-45 (in red).

Opposite edge is bevelled, equal spaced inch scale 0-10 by 1/8th to 1/32th. Also equal spaced scale marked lg .0-(1).0 by .01 to .002.

Slide front has 2 log scale and one reverse log scale. 0.8-120, 0.9-11, 11-0.9. Reverse labeled ex; three scales 1.01 to 1.12, 1.1 to 3.2, 2.5-105.

Stock under slide has inch scale (13)-(23) by 1/8th to 1/32.

The back of the rule has faint traces of a table of data which has been removed or erased.

References

Events

Description
This slide rule incorporates another calculating aid, a stylus calculator. In fact, the stylus calculator was in competition with the slide rule during the mid 20th century.

This instrument is a cylindrical slide rule, a variation on the most common type, also shown in this drawer, and described below.

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:45759