Accession No

1143

Brief Description

6-inch gunter sector, by Jesse Ramsden, English, 1760-1800 (c)

Origin

England; London

Maker

Ramsden, Jesse

Class

calculating; mathematics

Earliest Date

1760

Latest Date

1800

Inscription Date

Material

metal (brass); ivory

Dimensions

length 161mm; breadth 36mm; thickness 3mm

Special Collection

Robert Whipple collection

Provenance

Donated by Robert S. Whipple to the University of Cambridge in 11/1944 as part of the Whipple Museum of the History of Science’s founding collection.

Inscription

‘Ramsden,
London.’ (obverse)

Description Notes

6-inch gunter sector, by Jesse Ramsden, c. 1760 - c. 1800

6-inch ivory sector with brass hinge and shoulders.
Obverse has double scales of: ‘S’ (sines) divided [0] - 90˚, numbered by 10˚, 0 - 70˚ subdivided to 30´, 70˚ - 80˚ subdivided to 1˚, 80˚ - 85˚ subdivided to 2˚; ‘t’ (tangents) divided 45˚ - [75˚ 45´] numbered by 10˚ (and for 75˚), 45˚ - 50˚ subdivided to 30´, remainder subdivided to 15´; ‘T’ divided [0] - 45˚, numbered by 10˚, subdivided to 15´. On fully opened limbs single scales of ‘num’ (log numbers) divided 1 - 20[0], numbered ‘1, 2...9, 1, 2...10, 20’, 1 - 1[0] subdivided to 0.1, 1[0] - 3[0] subdivided to 0.5, 3[0] - 10[0] subdivided to 1, 10[0] - 20[0] subdivided to 2; ‘sin’ (log sinces) divided [50´] - [90˚], numbered 1, 2, 3...10, 20...70, 50´ - 6˚ subdivided to 5´, 6˚ - 10˚ subdivided to 10´, 10˚ - 20˚ subdivided to 15´, 20˚ - 30˚ subdivided to 30´, 30˚ - 70˚ subdivided to 1˚, 70˚ - 80˚ subdivided to 2˚; ‘tan’ (log tangents) divided [1˚ 25´] - 45˚ and back to 70˚], numbered 1, 2...10, 20, 30, 40, 45, 50, 60, 70, 1˚ 25´ - 6˚ subdivided to 5´, 6˚ - 10˚ subdivided to 10´, 10˚ - 30˚ subdivided to 15´, 30˚ - 45˚ subdivided to 30´.
Reverse carries double scales of: ‘L’ (lines or equal parts) divided [0] - 10, numbered by 1, subdivided to 0.05; ‘S’ (secants) divided [10˚] - 75˚, numbered by 10˚, 20˚ - 50˚ subdivided to 1˚, 50˚ - 60˚ subdivided to 30´, 60˚ - end subdivided to 15´; ‘C’ (chords) divided [0] - 60˚, numbered by 10˚, subdivided to 0.5; ‘Pol’ divided 12 - 4, numbered by 1. On upper limb single scales of: ‘I M’ (inclined meridian) divided [0] - 90˚, numbered by 10˚, subdivided to 1˚; ‘C’ (chords) divided [0] - 90˚, numbered by 10˚, subdivided to 1˚. On lower limb single scales of ‘L’ (latitude) divided [0] - [90˚], numbered by 10˚ (except 80), 0 - 70˚ subdivided to 1˚; ‘H’ (hours) divided [0] - VI, numbered by I, subdivided to 5 minutes. On the fully opened limbs single scale of inches, divided [0] - 12, numbered by 1, subdivided to 0.1.
Two brass pins to secure limbs together.

Condition good; complete

References

Events