Gunter Quadrant

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Description
This brass Gunter-type horary quadrant has one brass sight on the top of the quadrant along one radius. There is no pinhole in this sight; it is completely solid. It appears that there was never a second sight. The plumb-bob and string which belong at the vertex are missing. The quadrant contains a geometric square marked from 10 to 50 to 10 in units of one degree, an hour arc (U-shaped) from I to VI to XI to XII and an azimuth arc from 30 to 90 to 120 by ten degrees, an ecliptic arc calibrated by zodiac symbol, a declination scale to 24 degrees, a horizon arc marked from 10 to 30, a second hour arc marked from VIII to I, a calendar arch lettered by month, and a circumference marked from 0 to 90 in units of one-half degree. There are suns between most Roman numerals on the hour arcs, moons on each side of the calendar arch, and sets of three dots at each 5-degree mark on the circumference. Five stars are charted: VH, BE, LH, A, PW. This dial was made for a latitude of approximately 52 degrees. There is no instrument maker with initials T. D. who worked around 1790 in Clifton, or in the inventory of the National Maritime Museum, Greenwich.
References:
Gloria Clifton, Directory of British Scientific Instrument Makers..., Greenwich: National Maritime Museum, 1995.
An Inventory of the Navigation and Astronomy Collections in the National Maritime Musuem, Greenwich, National Maritime Museum.
Location
Currently not on view
date made
1790
Physical Description
brass (overall materials)
Measurements
overall: .6 cm x 12.5 cm x 12.5 cm; 1/4 in x 4 15/16 in x 4 15/16 in
ID Number
MA.330843
catalog number
330843
accession number
305777
See more items in
Medicine and Science: Mathematics
Trigonometry
Data Source
National Museum of American History, Kenneth E. Behring Center

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