semi-circular protractor
Datecirca 1765
Inventory Number0064
ClassificationProtractor
Subject
Maker
Edward Nairne
1726 - 1806
User
Department of Physics, Harvard University
founded 1884
Cultural Region
Place of Origin
Dimensions0.5 x 30.5 x 17.4 cm (3/16 x 12 x 6 7/8 in.)
Material
Bibliography
DescriptionThe 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.
Keuffel & Esser Company
Date: 1900-1950
Accessories: original cardboard sleeve case
Object number: 1997-1-1625
Gabriel & Edward Davis
Date: 1830-1850
Accessories: circular mahogany case with one straight edge
Object number: DW0386
Elliott Brothers
Date: 1855-1870
Accessories: mahogany storage case lined with blue velvet
Object number: DW0460
French
Date: circa 1740
Accessories: fitted case with embossed leather exterior and coarse canvas interior
Object number: DW0731
Keuffel & Esser Company
Date: 1954-1969
Accessories: mahogany case; 3/4 inch wrench; extra knobs
Object number: 1997-1-1859
French
Date: 1700-1750
Object number: DW0656