semi-circular protractor
Date: circa 1765
Inventory Number: 0064
Classification: Protractor
Subject:
Maker: Edward Nairne (1726 - 1806)
User: Department of Physics, Harvard University (founded 1884)
Cultural Region:
Place of Origin:
Dimensions:
0.5 x 30.5 x 17.4 cm (3/16 x 12 x 6 7/8 in.)
Material:
Bibliography:
The Apparatus of Science at Harvard, 1765-1800
Description:
The protractor is constituted of a (originally silvered) brass half circle with a cross bar along the diameter and has beveled edges. There are two 180-degree scales engraved along the circumference in opposite directions such that 0° of one scale lines up with 180° from the other. Every tenth degree is marked with the appropriate engraved numeral. The outermost scale has a bold line subdivision every five degrees. At the outermost edge, there is a small line for each single degree.
Signedengraved on instrument: E. Nairne LONDON
FunctionThis protractor is used for measuring angles or circles in degrees. The flat base of the half circle can be lined up with an angle edge or with the diameter of a circle and desired angles can be measured on the scales.
ProvenanceFrom the Department of Physics, Cruft Laboratory, Harvard University.