Diptych Sundial

Description:

This rectangular wooden diptych sundial consists of two pieces of wood joined with two metal fasteners. A hook at the backholds the instrument open (at something less than 90 degrees) and one at the front holds it closed. Paper scales and tables with black ink and red, green, and yellow coloring are glued to the faces. Leaf 1a is a latitude table for thirty-two European cities from Amsterdam to Zurich (complete list in accession file). Leaf 1b contains holes for latitudes of 40, 42, 44, 46, 48, 50, 52, 54, and 56 degrees, although only the holes 46-54 are drilled completely through the leaf and therefore functional. The string gnomon is missing. Leaf 1b also contains an equinoctial dial calibrated from VI to XII to VI by I. Leaf 2a contains a horizontal dial calibrated twice from 4 to 12 to 8 by 1 with divisions for each thirty-minute interval and once from VI to XII to VI by I with dots for each thirty-minute interval. There is also an inset compass (23 mm diameter) with glass, needle, and four labeled cardinal points inside the dial. The needle is a distinctive arrow with a brass piece bearing a cross atop the center of the needle. The compass is offset roughly 10 degrees west for variation. Leaves 1b and 2a are decorated with flowers and swags. The latitude table and compass directions on this dial mix German, French, and English terms (for example: Nord, Ost, Sud, West). This dial likely dates to the last quarter of the 1700s.

Location: Currently not on view

Subject: MathematicsTimekeeping

Subject:

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

Exhibition:

Exhibition Location:

Credit Line: Gift of The Reverend William Markley

Data Source: National Museum of American History

Id Number: MA.330854Catalog Number: 330854Accession Number: 1988.0532

Object Name: sundial, horizontal portablesundial, diptych

Measurements: overall: 1.8 cm x 4.5 cm x 8 cm; 23/32 in x 1 25/32 in x 3 5/32 in

Guid: http://n2t.net/ark:/65665/ng49ca746a8-d6f4-704b-e053-15f76fa0b4fa

Record Id: nmah_997123

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