Horizontal dial

Horizontal dial for latitudes 35°-45° North. The dial is contained in a gold painted rectangular tin. There is an hour scale around the edge of the dial-plate for 35°, an octagonal ring with an hour scale for 40° and an inner circular ring with an hour scale for 45°. Pivoted at the centre is a brass strip gnomon which folds into a slit on the dial-plate when not in use. The compass is missing. To the north of its hole is a scale for magnetic variation, divided 40°-[0°]-40°. Inside the lid is a table of towns and cities in the United States together with the corresponding magnetic variation, latitude and longitude, and the time difference from the relevant time zone. The right hand side contains a table giving the Equation of Time.

This instrument was probably intended for American boys and was based on the sundial design created by Ansonia. The information in the lid provides the means to adjust the clock time to any of the listed places. Another example of the US version of this sundial can be found at the History of Science Museum, Oxford (object number 48194), complete with the original paper slip-case and a booklet of instructions. Painted on the dial-plate is the following: 'M'F'D. BY OUTDOOR SUPPLY CO., INC., N.Y., U.S.A. PATENTED APR. 20. 1920 155244 SUNWATCH PATENTED MAY 10, 1921 1418936'.

A British and Irish version of the sunwatch was also manufactured and examples of this can be found in the collections of the Science Museum, London (object numbers 1996-229 and 1974-100) and the Whipple Museum, Cambridge (object number Wh:0389). Another version was designed for use in Australia and New Zealand.

For more information regarding this dial please refer to the OUP & NMM catalogue, 'Sundials at Greenwich'.

Object Details

ID: AST0196
Collection: Astronomical and navigational instruments
Type: Horizontal dial
Display location: Not on display
Creator: Outdoor Supply Co. Inc
Date made: 1921-1930; 1921-30
Credit: National Maritime Museum, Greenwich, London
Measurements: Overall: 9 x 50 x 75 mm

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