Accession No

0631

Brief Description

Gunter sector, 12-inch, by Jesse Ramsden, English, 4/4 18th Century

Origin

England; London

Maker

Ramsden, Jesse

Class

calculating; mathematics

Earliest Date

1775

Latest Date

1800

Inscription Date

Material

metal (brass)

Dimensions

length 326mm; breadth 82mm; thickness 6mm box length 345mm; breadth 109mm; height 26mm

Special Collection

Robert Whipple collection

Provenance

Purchased from T.H. Court on 05/11/1930.

Inscription

‘Ramsden
London’ (obverse)

Description Notes

Gunter sector, 12-inch, by Jesse Ramsden, 4/4 18th C

12-inch brass sector with folding friction leaf.
On the recto double scales of: ‘Lin’ (line of lines or equal parts) divided [0] - 10, numbered by 1, subdivided to 0.02; ‘Sec’ divided [0] - [75˚ 30´], numbered by 10 (and 75˚ marked), 0 - 10˚ subdivided to 5˚, 10˚ - 20˚ subdivided to 2˚, 20˚ - 30˚ subdivided to 1˚, 30˚ - 50˚ subdivided to 30´, 50˚ - 75˚ 30´ subdivided to 15´; ‘Cho’ divided [0] - 60˚, numbered by 10˚, subdivided to 15´; ‘POL’ (polygons) divided 12 - 4, numbered by 1. On the upper limb single scales of: ‘In. Me.’ (inclined meridian) divided [0] - 90˚, numbered by 10˚, subdivided to 1˚; ‘Cho.’ divided [0] - 90˚, numbered by 10˚, subdivided to 1˚; ‘Sin.’ divided [0] - 90˚, numbered by 10˚, 0 - 85˚ subdivided to 1˚. On the lower limb single scales of: ‘Tan.’, divided [0] - 45˚, numbered by 10˚, subdivided to 1˚; ‘Lat.’, divided [0] - 90˚, numbered by 10˚, 0 - 80˚ subdivided to 1˚, 80˚ - 90˚ subdivided to 5˚; ‘Hou.’ divided [0] - VI, numbered by I, subdivided to 5 minutes; ‘Cho’ divided 0 - 180˚, numbered by 10˚, 0 - 110˚ subdivided to 30´, 110˚ - 160˚ subdivided to 1˚, 160˚ - 170˚ subdivided to 2˚, 170˚ - 180˚ subdivided to 5˚. On the fully opened limbs, single scales of: [0] - [24] inches, numbered by 1, subdivided to 0.05; decimal foot divided [0] - 100, numbered by 10, subdivided to 0.5.
On the verso, double scales of: ‘Sin.’, divided [0] - 90˚, numbered by 10˚, 0 - 70˚ subdivided to 15´, 70˚ - 80˚ subdivided to 30´, 80˚ - 90˚ subdivided to 1˚; ‘tan’ divided 45˚ - [75˚ 45´], numbered by 10˚ (and for 75˚), subdivided to 15´; ‘Tan’ divided [0] - 45˚, numbered by 10˚, subdivided to 15´. On the upper limb single scale of ‘Rum.’, divided [0] - 8, numbered by 1, divided to 0.25.
On the lower limb single scale of ‘Lon.’, divided [0] - 60˚, numbered by 10˚, subdivided to 1˚. On the fully opened limbs single scales of: ‘Tan.’ (log tangents), divided [10´] - 45˚, numbered 1, 2...10, 20, 30, 40, 45, 10´ - 10˚ subdivided to 10´, 10˚ - 45˚ subdivided to 15´; ‘Sines’ (log sines) divided [10´] - 90˚, numbered 1, 2...10, 20...90, 10´- 10˚ subdivided to 10´, 10˚ - 40˚ subdivided to 15´, 40˚ - 60˚ subdivided to 30´, 60˚ - 80˚ subdivided to 1˚, 80˚ - 90˚ subdivided to 5˚; ‘V. Sines’ (log versed sines) divided [0] - [168˚ 30´], numbered by 10˚, 10˚ - 20˚ subdivided to 2˚, 20˚ - 90˚ subdivided to 1˚, 90˚ - 120˚ subdivided to 30´, 120˚ - end subdivided to 15´; ‘Num.’ (log numbers) divided 1 - 10[0], numbered 1, 2..9, 1, 2...10, 1 - 5 subdivided to 0.02, 5 - 1[0] subdivided to 0.05, 1[0] - 5[0] subdivided to 0.1, 5[0] - 10[0] subdivided to 1.
Friction leaf carries scratched name: ‘N. Grafton’ (owner ?)

Condition good; complete

References

Events