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"BRANDIS & SONS, BROOKLYN, N.Y." and "5296"
and "U.S. NAVY NO. 2977"
radius 6 inches
Three Navy-Curtiss (NC) flying boats took off from Rockaway, Long Island, in early May 1919. Three weeks later, after stops in Nova Scotia, Newfoundland, the Azores, and Lisbon, the NC-4 landed in Plymouth, England, thereby becoming the first plane to fly across the Atlantic. Richard Evelyn Byrd, later famous as a naval aviator, designed the sextants for this important adventure. This is one of those instruments. P. V. H. Weems, Byrd’s colleague and classmate, donated it to the Smithsonian in 1963.
This is a standard marine sextant modified for aeronautical use. The frame is brass. The silvered scale is graduated every 20' from -5o to +185o and read by vernier with tangent screw and magnifier to 30" seconds of arc. A bubble level mounted on the frame below the filters for the horizon glass serves as the artificial horizon. There is a telescope with a "specially constructed lens" for use with the bubble, and electrical illumination for taking bubble observations at night. A certificate in the box shows that the U.S. Naval Observatory inspected this instrument on March 16, 1919.
Ref: "New Devices Aid Navy Seaplanes," New York Times (May 12, 1919), p. 1.