Accession No

5991

Brief Description

gunter quadrant, by Isaac Carver, English, 1706

Origin

England

Maker

Carver, Isaac

Class

dials

Earliest Date

1706

Latest Date

1706

Inscription Date

1706

Material

wood (boxwood); metal (brass)

Dimensions

139mm radius; 10mm thickness

Special Collection

Provenance

Donated on or before 24/03/2004. The donor suggests that their Mother purchased the quadrant on King's Road, Chelsea, about 1960.

Inscription

'ISAAC CARVER fecit 1706' (obverse)
'GEORGE LASON 1706' (obverse; ownership inscription)

Description Notes

Boxwood Gunter quadrant with rectilinear network on reverse, stamped markings, and maker's and owner's inscriptions.
Although the design follows that found in Gunter's De Sectore et Radio (1623), and boxwood Gunter-type quadrants are common dating from the late seventeenth century and early eighteenth century, this particular quadrant is notable for a number of reasons. Wooden quadrants of this type are normally blank on the reverse but this quadrant carries a sinical quadrant; star tables normally carry only the right ascension, but this quadrant includes additional values for declination, arc, and 'months', i.e. the date at which the star crosses the meridian at midnight; this quadrant lacks a shadow square, but includes both the scale of the shadow square and a 'line of shadows' as described in Collins The Sector on a Quadrant; the azimuth lines are drawn for every 5˚ rather than the usual 10˚.
Obverse: Gunter’s projection for 52˚ N. Ecliptic arc, divided to zodiac sign, subdivided to 1˚. Horizon arc divided [0] - [40˚], numbered by 5˚, subdivided to 1˚. Declination scale divided [0] - [23˚ 30´], numbered by 10˚, subdivided to 1˚. Curved hour lines divided 6 - 12, 12 - VIII (summer) and 6-12, 12 - 5 (winter); half-hour lines also marked. Curved azimuth lines divided [0] - 125˚ for every 5˚; 10˚, 20˚, 30˚, 40˚, 50˚ also marked below. Circumference degree scale divided [0] - 90˚, numbered by 10˚, subdivided to 30´. Scale of the shadow square divided 0 - 100 - 0, numbered by 10, subdivided to 1. Line of shadows divided 50 - 20 - 10 - 5 - 4 - 3 - 2 - 1 (at 45˚) and back to 50 in like manner; subdivided to .1 between 1 and 4, to .5 between 4 and 5, 4 divisions between 5 and 10, to 1 and then 5 between 10 and 20, to 15 between 20 and 50. Date scale divided to named month, subdivided to 2 days (5 days at solstices); decorated with a fleur-de-lys at either end. 5 stars marked 1 to 5 plotted on the projection; listed with months, right ascension, arc, and declination in a table at the apex of the quadrant (surrounded by a fleur-de-lys at each side): 1 Pega.W [Pegasus's Wing tip], 2 Artur [Arcturus], 3 Lion.H [Lion's Heart], 4 Buls.Ei [Bull's Eye], 5 Vul:H [Vultures Heart]. Pierced brass plug at apex to hold plum-line.
Reverse: sinical quadrant with rectilinear network divided at either edge [0] - 60, numbered by 10, subdivided to 1; network circumference divided [0] - 8, numbered by 1, subdivided to .25; line inscribed between apex and '4' (45˚) at the circumference. Quadrant circumference degree scale divided [0] - 90˚, numbered by 10˚, subdivided to 30´.

Condition: good (obverse: long stain originating around 50˚ on the circumference and crossing the projection; reverse: one dark stain on right hand side of network); incomplete (both sights, plumb-line and bob missing).

References

Boris Jardine; 'A Gunter quadrant and practical knowledge'; Explore Whipple Collections online article; Whipple Museum of the History of Science; University of Cambridge; 2008: https://www.whipplemuseum.cam.ac.uk/explore-whipple-collections/astronomy/maps-heavens/gunter-quadrant-and-practical-knowledge

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