military protractor
Date: circa 1940
Inventory Number: 2004-1-0374
Classification: Protractor
Subject:
Maker: Union Instrument Corporation
Cultural Region:
Place of Origin:
Dimensions:
instrument: 2.6 × 15.6 × 37 cm (1 × 6 1/8 × 14 9/16 in.)
case: 4.5 × 16 × 37 cm (1 3/4 × 6 5/16 × 14 9/16 in.)
Accessories: wooden case
DescriptionProtractor is stored in a rectangular wooden case, painted black, that opens with two hings along one long edge. The inside of the case is lined with black fabric and the leftmost edge is slightly extended such that the protractor will slide under the lip when stored.
Instrument consists of a brass semi-circular protractor with two pivoting brass arms attached to the center of the diameter. In the center of the diameter is a small brass circle with a window in the center marked with a black cross for accurate placement of the instrument. The circumference of the semi-circle is divided into degrees that are marked with two scales. The inner scale begins with 190° and reduces incrementally to 0° followed after ten increments by 350°. The outer scale begins with 350° followed after ten increments by 0° and then increses to 190° on the right.
Attached to the longest pivoting arm is a conical brass window piece that slides over the protractor circumference revealing the degree scales through the cutout window. This arm extends well beyond the circumference of the protractor and acts as a straight-edge. At its outer edge is a small round handle for rotation. The shorter pivoting arm extends the radius of the protractor. It has a spring mechanism and a handle attached on the top.
Instrument consists of a brass semi-circular protractor with two pivoting brass arms attached to the center of the diameter. In the center of the diameter is a small brass circle with a window in the center marked with a black cross for accurate placement of the instrument. The circumference of the semi-circle is divided into degrees that are marked with two scales. The inner scale begins with 190° and reduces incrementally to 0° followed after ten increments by 350°. The outer scale begins with 350° followed after ten increments by 0° and then increses to 190° on the right.
Attached to the longest pivoting arm is a conical brass window piece that slides over the protractor circumference revealing the degree scales through the cutout window. This arm extends well beyond the circumference of the protractor and acts as a straight-edge. At its outer edge is a small round handle for rotation. The shorter pivoting arm extends the radius of the protractor. It has a spring mechanism and a handle attached on the top.
Signedengraved on instrument arm: UNION / INST. CORP. / PLAINFIELD / N.J.
Inscribedengraved in instrument arm: MADE IN USA / 8" . U.S.
FunctionProtractors are mathematical instruments used to measure and plot angles. In each case, the center of the 180 degree to 0 degree crossbar must be aligned with the vertex of the angle in question. The long pivoting arm can be used as a straight edge when plotting an angle edge, or as a measurement aide, when aligned with an angle edge. With the added length of the long metal bar to which the protractor is attached, users can draw precise and larger angles.
Curatorial RemarksOthers like this one are found with stamp USCE (United States Corps of Engineers). This one only has US on it.
ProvenancePrivate Donor, Troy NY, 2004.