Accession No
0919
Brief Description
quadrant, by C. Blunt, English, 1st quarter 19th century
Origin
England; London; 38 Tavistock Street
Maker
Blunt, C.
Class
navigation
Earliest Date
1800
Latest Date
1825
Inscription Date
Material
metal (brass, oxidised brass); rope (string)
Dimensions
height 241mm; breadth 131mm; depth 145mm
Special Collection
Robert Whipple collection
Provenance
Inscription
‘C. Blunt Tavistock Strt. London’ (base)
Description Notes
Pierced brass quadrant mounted on stand which rotates over circular base with three brass levelling screws. Quadrant altitude mount on stand which moves in azimuth with index moving over degree scale on base divided 0 - 90 - 0 - 90 - 0, numbered by 10˚, subdivided to 1˚. Scale on quadrant divided 0 - 90, numbered by 10˚, subdivided to 1˚ and read by plumb-bob, consisting of string and brass bob. Pinhole and crosswire sights with sliding dark glass over pinhole.
Condition good; complete, plumb bob has snapped off.
References
Events
Description
Quadrant
A quadrant is a quarter of a circle, and there are different types of instrument that come under that description. The size of quadrants varied hugely from Tycho Brahe’s highly successful huge 2m radius one, to the more portable versions of the 18th century. In all examples it was important to keep movement, wear and flexure to a minimum, especially if results were to form part of an extended research program and to be compared with one another.
The quadrant was the principle measuring instrument of astronomy in the 17th and 18th centuries, being used in all major observatories. Plain sights (where the angle was simply read off by eye) were replaced by telescopic sights in more sophisticated examples.
18/10/2002
Created by: Saffron Clackson on 18/10/2002
FM:39649
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