This has a brass frame, a scale that extends from -5o to +135o and an unusual flat micrometer that reads to 1' of arc. A similar micrometer appeared on a bubble sextant described by a Dr. Hartmann in 1912. Herman Haecke began in business as a nautical instrument maker in the 1870s, in an area of Berlin that would later be known as Neukölln. The U.S. Naval Observatory transferred this instrument to the Smithsonian in 1963.
Ref: Hartmann, "Ein Libellenquadrant in neuer Form," Deutsche Luftfahrer Zeitschrift 16 (Oct. 2, 1912): 495-496.
K. H. Beij, "Astronomical Methods in Aerial Navigation." Report of the National Advisory Committee for Aeronautics 198 (1924), p. 13.
