U.S. Navy Bureau of Navigation Mark II Sextant — David White Co., Milwaukee — Serial No. 647-1939 — With Original U.S. Naval Observatory Certificate of Inspection, dated August 15, 1941

The Navy Mark II sextant by David White Company of Milwaukee was one of the principal instruments of U.S. Navy navigation throughout World War II. This example, serial number 647-1939, was inspected and certified by the U.S. Naval Observatory in Washington on August 15, 1941 — just four months before Pearl Harbor — making it a genuine pre-war/early-war service instrument. The limb reads to single degrees with drum micrometer to 1 minute, and vernier to 6 seconds of arc. Original mahogany dovetailed case with brass hardware and David White Company nameplate. Original inspection certificate with handwritten eccentricity corrections and inspector’s signature survives intact. Telescope present.