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Date: circa 1805

Inventory Number: 0067

Classification: Slide Rule

Subject:

Maker: W. & S. Jones (fl. 1791 - 1859)

User: John Farrar (1779 - 1853)

Cultural Region:

Place of Origin:

Dimensions:

82.6 x 6.5 x 1.1 cm (32 1/2 x 2 9/16 x 7/16 in.)

Bibliography:

The Apparatus of Science at Harvard, 1765-1800

Description:

This slide rule is in the shape of a long rectangle and is made of fruit wood. Its grooved central slide is held together at both ends by riveted brass clamps. The slide is fitted with two precision adjusting screws. The number of graduated lines is large: A, B, C, D, CF, DF, CI, K, S, T, SRUM, TRUM, VBIN, SIN, NUM, TAN, MER, MD, DL, CHO, STAN.

Another set of lines is called Gunter's scale. It was a set of lines designed by Edmund Gunter in the sevententh century to perform any number of calculations with logarithms. Following Gunter's design, the logarithmic scale was often in navigation, where it facilitated calculations of spherical triangles.

This slide rule also has a moving cursor or index, which was introduced in the second half of the eighteenth century by John Robertson, Librarian fo the Royal Society.

Another set of lines is called Gunter's scale. It was a set of lines designed by Edmund Gunter in the sevententh century to perform any number of calculations with logarithms. Following Gunter's design, the logarithmic scale was often in navigation, where it facilitated calculations of spherical triangles.

This slide rule also has a moving cursor or index, which was introduced in the second half of the eighteenth century by John Robertson, Librarian fo the Royal Society.

In Collection(s)

Signedengraved on brass end clip: W & S Jones / 30 Holborn London

FunctionThe slide rule did not generally perform addition or subtraction. It was rather used to perform multiplication and division, or any other "scientific" functions such as roots, logarithms, and especially trigonometry. This particular slide rule was outfitted with graduated lines that emphasized its use in navigation.

Historical AttributesIn W & S Jones's catalogue of 1822 one can read: "[Gunter's] Three-foot ditto [sliding navigation scales] improved by Robertson, with brass adjusting screws, &c. being the completest scale of the kind. [price] 1 15 0."

This is the same price Harvard paid when it received this particular slide rule in 1805, which was labeled in the following way in the invoice: "An improved Robertson's gunters with improved adjusting screw–1.15.0".

The slide rule also appears in an inventory of apparatus of the Hollis professorship of mathematics and natural philosophy, taken in 1807 when John Farrar became Hollis professor.

This is the same price Harvard paid when it received this particular slide rule in 1805, which was labeled in the following way in the invoice: "An improved Robertson's gunters with improved adjusting screw–1.15.0".

The slide rule also appears in an inventory of apparatus of the Hollis professorship of mathematics and natural philosophy, taken in 1807 when John Farrar became Hollis professor.

Primary SourcesW. and S. Jones, *A Catalogue of Optical, Mathematical and Philosophical Instruments* (London, 1822).

ProvenanceHarvard College, 1805 purchase.

Published ReferencesDavid P. Wheatland, *The Apparatus of Science at Harvard, 1765-1800* (Cambridge: Harvard University Press, 1968), 82.

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