Equinoctial Sundial by Dion Geerts

Equinoctial Sundial by Dion Geerts

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This brass universal equinoctial ring dial consists of a meridian ring, hour ring, rotating crosspiece or bridge, and sliding suspension ring/handle. One side of the meridian ring contains a nautical quadrant calibrated for solar altitude from 0 to 80 by single degree. The hour ring is calibrated on one side from I to XII x 2 by I. The hour ring is also calibrated along its inside edge from 1 to 12 x 2 by 1. The bridge has a pinhole gnomon sliding over a calendar scale calibrated and lettered by month and by zodiacal sign on verso. A previous cataloguer commented that: "Cursor track not long enough to allow cursor to reach winter solstice mark. Capricorn and Cancer apparently drawn outside annual path of sun. First point of Aries taken as midpoint of scale." Both sides of the meridian ring and one side of the hour ring are engraved with a list of 40 European cities and latitudes from Copenhagen to Malta and Dublin to Moscow. There is some artistic engraving on the gnomon and bridge.
Currently not on view
Object Name
sundial, equinoctial
Geerts, Dion
overall:.5 cm x 7.1 cm x 8.5 cm; 3/16 in x 2 25/32 in x 3 11/32 in
ID Number
catalog number
accession number
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Medicine and Science: Mathematics
Science & Mathematics
Data Source
National Museum of American History
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