Gunter's quadrant with nocturnal
Date: circa 1625
Inventory Number: 7361
Classification: Astrolabe Quadrant
Subject:
Attributed to: Elias Allen (circa 1588 - 1653)
Cultural Region:
Place of Origin:
Dimensions:
1 x 20 x 14.7 cm (3/8 x 7 7/8 x 5 13/16 in.)
radius: 14.2 cm (5 9/16 in.)
DescriptionThis is a variant of the Gunter's quadrant with a nocturnal on the reverse. It is made of brass. Moving from the apex to the limb, the quadrant has the following components:
Plumb line with bob wrapped in leather. The bob is a replacement. Sights are on the right-hand edge of the quadrant.
Calendar scale in four bands with months labeled in English abbreviations, and divisions into days.
Arc of solar declination running 0°-23 1/2° with divisions every 1°.
Equal hours are marked from IIII-XII-VIII, subdivided by 1/2 hours. The ecliptic is divided every 1° and marked with zodiacal symbols.
Lines of azimuth are inscribed 0°-120°, every 10°.
The shadow scale is of 100 parts, divided into intervals 0-10-0. The degree scale on the limb runs 0°-90° with subdivisions every 30'.
On the reverse, there is a nocturnal marked for hours I-XII twice by 1/8 hours around the edge of a volvelle. Along the outer limb of the volvelle, running adjacent to the hour scale, there is a calendar scale. It is divided into days and monthly intervals are indicated by English initials. The center of the volvelle has figures representing six constellations.
Plumb line with bob wrapped in leather. The bob is a replacement. Sights are on the right-hand edge of the quadrant.
Calendar scale in four bands with months labeled in English abbreviations, and divisions into days.
Arc of solar declination running 0°-23 1/2° with divisions every 1°.
Equal hours are marked from IIII-XII-VIII, subdivided by 1/2 hours. The ecliptic is divided every 1° and marked with zodiacal symbols.
Lines of azimuth are inscribed 0°-120°, every 10°.
The shadow scale is of 100 parts, divided into intervals 0-10-0. The degree scale on the limb runs 0°-90° with subdivisions every 30'.
On the reverse, there is a nocturnal marked for hours I-XII twice by 1/8 hours around the edge of a volvelle. Along the outer limb of the volvelle, running adjacent to the hour scale, there is a calendar scale. It is divided into days and monthly intervals are indicated by English initials. The center of the volvelle has figures representing six constellations.
In Collection(s)
Signedunsigned
FunctionThe Gunter's quadrant is a type of astrolabe quadrant devised by Edmund Gunter in the early 1620s. Like an astrolabe, it has a planispheric projection of the celestial sphere and local altazimuth coordinates, but these are "folded up" so as to be inscribed on a quadrant rather than a disk. The instrument was used for observations of the sun and stars, astronomical calculations, time finding, and surveying.
The nocturnal is an instrument for finding time at night by means of the rotation around the Pole Star by key stars in Ursa Major or other constellations.
The nocturnal is an instrument for finding time at night by means of the rotation around the Pole Star by key stars in Ursa Major or other constellations.
Curatorial RemarksAttribution to Elias Allen based on style of engraving and a similar Gunter's quadrant / nocturnal combination by him. See also nocturnal on compendium in MHS, Oxford, 36259.
First point of Aires is March 10. The shape of the 3's and 5's is consistent with 17th century engraving and 2's are consistent with the latter part of the 17th century. The use of three balls for marking intermediate divisions and the use of the Julian calendar supports the claim of English origin. The engraving is of high quality.
XRF analysis of the metals was done by Katherine Eremin and Sara Schechner in August 2007.
First point of Aires is March 10. The shape of the 3's and 5's is consistent with 17th century engraving and 2's are consistent with the latter part of the 17th century. The use of three balls for marking intermediate divisions and the use of the Julian calendar supports the claim of English origin. The engraving is of high quality.
XRF analysis of the metals was done by Katherine Eremin and Sara Schechner in August 2007.
