Portable Horizontal Sundial by Johann Martin

Portable Horizontal Sundial by Johann Martin

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Description
This octagonal, Augsburg-type dial consists of a brass base resting on 3 levelling screws and a dial made of silver-colored metal. There is some scrolling on the brass around the dial. The string gnomon folds up on a hinge. The string must be cut and retied in a different hole on the gnomon to read the dial at a different latitude. These holes are marked from 53 to 49. The outermost scale on the dial is calibrated from IIII to XII to VIII by I with stars at the half-hour points. The next scale (for the lunar month) is calibrated from 28 to 1. The innermost scale rotates for alignment against the lunar days. It is calibrated (in red) from 1 to 12 twice in succession. There is a glass-covered 4-point lettered compass with needle in a casing at the center of the dial. The compass abbreviations are for the directions in Latin: Septentrio, Occasus, Meridies, and Ortus. There is an extra arrow on the compass rose which points just west of north. There is a brass flower decoration screwed to the underside of the dial. It does not seem to support the gnomon arm even though it is underneath the arm. The list of cities and latitudes on the brass underside of the compass casing is probably in German. There is a leather-covered octagonal case for this dial. The case is stored in a separate bag within the same drawer.
Johann Martin (1642-1720) was born in Frankfurt on Main, but living in Augsburg by the time of his marriage in 1669. He dated instruments made in 1693, 1706 and 1710. Thus, although this instrument is undated, it is assigned a rough date of 1700.
Location
Currently not on view
Object Name
sundial
date made
1700?
maker
Martin, Johann
place made
Germany: Bavaria, Augsburg
Measurements
overall: 1.7 cm x 6.5 cm x 6.8 cm; 21/32 in x 2 9/16 in x 2 11/16 in
ID Number
MA.319074
accession number
236081
catalog number
319074
subject
Mathematics
Timekeeping
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Data Source
National Museum of American History
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