Universal Equinoctial Sundial

Universal Equinoctial Sundial

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Description
This brass equatorial (also called equinoctial) sundial is dated 1736. It consists of a rectangular base from which a vertical post extends. A quadrant of 10 cm radius, hour dial of 12 cm diameter, and calendar ring are at right angles to each other at the top of the post. The base is calibrated from 0 to 90 four times by single degree. The five and ten degree points are lettered. There is a small pedestal at the center of the base next to the vertical post which contains a pointer. This pointer is permanently set for variation to twenty-one degrees west of North. A decorative piece on top of the pedestal is for a missing plumb. The bob is tied with a string to an eyehole roughly two-thirds up the post. The quadrant is calibrated from 0 to 90 by single degree with the 5 and 10 degree points lettered. It can be set to the latitude by means of a brass clip. A pointer for the quadrant is screwed to the vertical post. A small steel pin sticks out of the top of the quadrant; its purpose is uncertain since the semicircle in which it is contained is not marked. The hour ring is calibrated from 1 to 12 two times by units, with hash marks at the half-hour points. The gnomon is a steel pin, 2.8 cm in length. The calendar ring is actually approximately a 3/4 circle. It is calibrated and lettered by month on one side and zodiac sign on the other. A sighting alidade is affixed to the center of the calendar ring. The alidade and gnomon are listed as missing on the original catalog card and so may have been added in a restoration. The earlier cataloguing also described this unusual sundial as a "Schinsauge composite mining instrument," probably from a Southern Germany mining town.
Location
Currently not on view
Object Name
sundial
Physical Description
metal (overall material)
Measurements
overall: 38.1 cm x 17.3 cm x 15.2 cm; 15 in x 6 13/16 in x 5 31/32 in
ID Number
MA.317351
accession number
230279
catalog number
317351
subject
Mathematics
Timekeeping
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Data Source
National Museum of American History
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