Equinoctial Sundial by Thomas Tretsch


This brass universal equinoctial ring dial consists of a meridian ring, hour ring, rotating crosspiece or bridge, and suspension ring / handle. The meridian ring is calibrated on one side for solar altitude by a nautical quadrant from 0 to 80 by single degree. The hour ring is calibrated on one side from I to XII x 2 by I. The bridge contains a pinhole gnomon sliding over a calendar scale calibrated and lettered by month, with zodiacal sign on verso. The opposite side of the meridian ring contains a list of several European towns and latitudes which are carelessly and faintly engraved. The suspension ring is screwed into a ferrous metal casing which fixes it at 33 degrees. This support casing may not be original since 33 degrees is well south of the cities given on the dial. Tretsch was a maker from eastern Germany or Austria. Although there are some attempts at decorative work on this dial, including a metal fish screwed to the reverse side, the workmanship overall is poor.

Maker: Tretsch, Thomas

Location: Currently not on view

Subject: MathematicsTimekeeping


See more items in: Medicine and Science: Mathematics, Science & Mathematics


Exhibition Location:

Data Source: National Museum of American History

Id Number: MA.336093Accession Number: 316529Catalog Number: 336093

Object Name: Sundial, Equinoctial

Measurements: overall: .5 cm x 7.6 cm x 9 cm; 3/16 in x 3 in x 3 17/32 in

Guid: http://n2t.net/ark:/65665/ng49ca746aa-a71e-704b-e053-15f76fa0b4fa

Record Id: nmah_1121607

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