Drawing Instrument, Coordinate Window

Drawing Instrument, Coordinate Window

Usage conditions apply
This small flat piece of translucent plastic has indicated on it a 10x10 grid of squares. The lines forming the grid are numbered from 0 to 10 along the base and along the left side of the grid. Units on the grid represent 100 yards, on a scale of 3 inches = 1 mile (e.g. one side of the grid represents 1000 yards).
The instrument was used – and possibly made - by Alfred J. Betcher (1887-1971), who studied engineering at West Point and went on to rise to the rank of colonel in the U.S. Army.
Reference: Accession file.
Currently not on view
Object Name
Drawing Instrument
overall: 10.4 cm x 11.5 cm; 4 3/32 in x 4 17/32 in
ID Number
catalog number
accession number
Credit Line
Gift of John A. Betcher
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Data Source
National Museum of American History
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