Accession No

1266

Brief Description

repeating circle (astronomical), by Troughton, English, 1810 (c)

Origin

England; London

Maker

Troughton

Class

astronomy; surveying

Earliest Date

1810

Latest Date

1810

Inscription Date

Material

glass; metal (brass, silver, gold); ivory

Dimensions

radius 240mm; height 800mm

Special Collection

Provenance

On loan from St. John's College, University of Cambridge, from 09/1953. Donated by Thomas Catton (1760-1838) (F.R.S. 1821) to St John’s College. Gunther no. 226.

Inscription

‘Troughton London’

Description Notes

Repeating circle (astronomical), Troughton, England, c. 1810, brass.

Circle divided on silver 0 - 360˚ by 1˚, subdivided to 10’. Two 2ft telescopes, both with OG covers with apertures and pivoted covers, screw-in OGs rack and pinion focus, screw-in eye ends give access to cross hairs, screw-in eyepieces with slots for shades. One telescope linked to 4 index arms, each with type-B verniers on silver, one with clamp and tangent screws. Two reading microscopes pivoted to arm which in turn pivots about centre of circle. Second telescope linked to back of circle by clamp, with tangent screws. Connected also to bubble level with ivory scale above and semi-circle divided on brass 100 - 0 & 0 - 100 by 1˚, subdivided to 20’. Circle has clamp and tangent screws. Semi-circle (no scale) with clamp for setting inclination of circle. Transverse bubble level. Counter-weight. Fork mount linked by 2 screws to pillar stand. Flat tripod base with three levelling screws, horizontal circle with gold scale divided 0 - 360˚ by 1˚, subdivided to 10’. Reading microscope on pivoted arm.

Condition: good.

References

Joshua Nall; ‘Famine and Astronomy’; Explore Whipple Collections online article; Whipple Museum of the History of Science; University of Cambridge; 2020: https://www.whipplemuseum.cam.ac.uk/explore-whipple-collections/astronomy-and-empire/famine-and-astronomy

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