This instrument, the 34th example of the Pioneer Model 342, is compact and
light; its optical train uses prisms rather than mirrors; the bubble chamber is
placed in the optical path; and the dial is illuminated with radium paint, thus
obviating the need for battery and electric light. A tag on the side reads
"C. L. SEWARD." Jerry Seward donated it to the Smithsonian in 1993.
Ref: "Recent Developments in Pioneer Aircraft Instruments," Aviation Engineering 7 (Oct. 1932): 16-17.
Victor E. Carbonara, "Navigating Instrument," U.S. patent
Victor E. Carbonara, "Sextant," U.S. design patent #85,912.