This sextant was probably made for use in World War I. Brandis termed it
a "U.S. Navy surveying sextant, 6 inch radius, reading 30 seconds of
arc." New it cost $120. The frame is anodized brass. The silvered scale is
graduated every 10 minutes from -5o to +182o and read by vernier with tangent screw and magnifier. The words "U.S. Navy-N-4705" are scratched onto the arc.
Ref: Brandis & Sons Mfg. Co., Catalogue No. 20. Instruments of
Precision (Brooklyn, n.d.), p. 298.