Diptych Pocket Sundial

Astronomy

Accession Number: 2019.ast.261

Description:

This is a small rectangular wooden instrument covered on the top in decorated paper. It consists of two rectangular sections of wood that are hinged at one end, and can be closed with a small hook latch. A length of red string is connected to the outer edge of the base block and passes through a small hole in the top block; on the exterior of the top the string is wound around a small metal peg.

Set in the bottom piece of wood there is a small round compass covered by a glass cover. Visible inside is a freely rotating needle, and painted on the base of the compass a compass rose, which is labelled in the four cardinal directions “NORD” “OST” “SUD” “WEST” around the rim. On the surface of the bottom section of the instrument, around the edges of the recessed compass, there is a decorated paper dial with hours indicated in Arabic numbers on radiating lines. “12” is located at the top.

On the inside surface of the top half of the opening section there is another paper dial, indicated in Roman numerals, with “XII” at the base. Through the top of this, with the gnomon string passing through it, there are is a list of pairs of numbers, each of which has a small hole through wooden block the centre. The gnomon string can be set at different angles by passing it through a different hole. The numbers indicated here range from 40 at the bottom to 56 at the top. There is a small metal pin set in the face of the dial; this fits into a small hole on the underside of the top box.

Written on the top of the upper block are a list of European cities, listed in alphabetical order, and their respective latitudes.

Alternative Name: Diptych Sundial

Primary Materials:

Wood, Textile: Cotton?, Paper, Metal: Copper Alloy

Markings:

On the base of the compass: “J.G. Kleininger fec[?]”

Handwritten on pencil on the base: “Berlin 19[5?]2” (could be “1932”)

Function:

This instrument was designed to be a portable tool that would permit the user to tell the time by shadows cast by the sun. The compass would assist with correctly orienting the instrument. The gnomon is adjustable to enable calibration of the instrument by latitude for accurate usage.

Condition:

Very Good: The top surface of the instrument is somewhat worn, particularly at the ends of the blocks, where the paper cover is damaged. The other exterior surfaces are in good condition, with small dirty marks. The latch and hinges still function well.

The interior of the instrument is in good condition, with a little yellow discolouration on the white portions of the paper faces. The glass of the compass dial is somewhat dirty. The string gnomon is intact.

Manufacturer: J.G. Kleininger

Date of Manufacture: c. 1775

Provenance:

This instrument was acquired as an antique by Reynold K. Young, former Director of the David Dunlap Observatory (1935-1946), likely as a display object. Since, it has been either on display at the department or in storage at the David Dunlap Observatory in Richmond Hill, or at the Department of Astronomy and Astrophysics building on the St. George Campus at the University of Toronto.

Additional Information and References:

Information about sundials of this type can be found at compassmuseum.com. [17/10/19]

Information about the maker was found at adlerplanetarium.org. [17/10/19]