Accession No
1637
Brief Description
engineer’s slide rule, by G. Buck, English, c. 1900
Origin
England; London; 242 Tottenham Court Road
Maker
Buck, G.
Class
calculating
Earliest Date
1900
Latest Date
1900
Inscription Date
Material
wood (boxwood); metal (brass, steel)
Dimensions
length closed 315mm; breadth 41mm; thickness 3mm
Special Collection
Provenance
Purchased from Christopher Sykes Antiques, 11 Market Place, Woburn, Bedfordshire, England, on 16/10/1972.
Inscription
‘G.BUCK 242 TOTTENHAM COURT ROAD LONDON’ (obverse)
‘H.LEWIS [& CO]
109 Mount Street
W.’ (obverse)
Description Notes
Boxwood folding rule and slide rule with brass hinge and shoulders, and steel bindings at tips of limbs. Two brass pins to hold rule together when closed. Letters and figures all stamped.
Obverse: top limb with brass slider. On the stock, log scale marked ‘A’, divided [1] - 10[0], numbered 1, 2...1[0], 12, 2[0], 3[0]...10[0]. Similar log scales on slider, marked ‘B’ and ‘C’. On the stock, further log scale marked ‘D’ and ‘Girt Line’, divided [4] - 40 numbered by 1 with gauge points for ‘WG’ and ‘AG’. Reverse of slide has inch scale divided [0] - [12], numbered by 1, subdivided to 1/8. Lower limb has scales for 1/4 inch, 3/8 inch, 1/2 inch, 5/8 inch, 3/4 inch and 1 inch.
Reverse: inch scale divided [0] - [24], numbered by 1 (except 11, 12 and 13), subdivided to 1/8; 0 - 6 subdivided to 1/16. Inner edge of upper limb carries equal scale marked ‘E’ divided [0] - 36 numbered by 2 subdivided to 0.5. Inner edge of lower limb has equal scale marked ‘M’ divided 0 - 50 numbered by 2 subdivided to 0.5.
Outer side of each limb carries decimal foot scale divided [0] - [100], numbered by 10, subdivided to 1.
Condition fair (steel rusty, some staining, slider very stiff and one pin for moving slide is missing); 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:42265
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