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Bubble Sextant

Catalogue number:
NASM 1957-388

Inscriptions:
"BRANDIS & SONS, INC. / BROOKLYN, N.Y. / 206C-109" and "AERONAUTICAL OCTANT / MARK 1 MODEL 4 / BU. AERO SERIAL 15-31." The telescope is marked "BRANDIS & SONS, INC. / BROOKLYN, N.Y" and "AERONAUTICAL OCTANT / MARK I MODEL 4 / BU. AERO SERIAL 15-31" and "WILLSON TELESCOPE / PATENT 1705146 / OTHER PAT. PENDING 206C-109"

Dimensions:
radius 5.25 inches

Discussion:
This is a small left-handed octant with a Willson bubble telescope, a Fischer rapid release lever, a drum micrometer, an electric light over the bubble and divided arc, a battery in the handle, and a radium illuminator for star observations. Since the legs are on the front of the frame, the octant can be set down with the handle uppermost. The Navy Bureau of Aeronautics designated this the Mark I, Model 4. The pending patent has not been identified.

This was the 109^th example of the Model 206C, and the 15^th example made for the Navy in 1931. The National Bureau of Standards transferred it to the Smithsonian in 1963.

Ref: R. W. Willson, "Instrument Including Means for Determining the Horizontal Direction," U.S. patent #1,705,146

Pioneer Instrument Co., "Aircraft Octant, Type 206 with Willson Bubble Telescope, Instructions," and "Appendix to Instructions for Octant Mark I, Model 4," both accompanying this instrument.

Further Information:

Brandis
Aircraft Sextant