The U.S. National Bureau of Standards established an Aeronautical Instruments Section in 1918 in order to collect, evaluate, and develop instruments for American use. Working with the Navy, they designed an aircraft sextant that closely resembled one developed in Britain and favored by the Royal Air Force. The Bausch & Lomb Optical Co. produced this American instrument for the Bureau of Standards in 1924, and an improved version a few years later. Various features of this instrument were covered by patents issued to Franklin L. Hunt and Karl Hilding Beij, both of whom worked for the Bureau of Standards.
Ref: F. L. Hunt and K. H. Beij, "Aircraft Sextant," U.S. patent #1,531,615.
F. L. Hunt and K. H. Beij, "Liquid Level," U.S. patent #1,674,550.
K. H. Beij, "Means for Determining Altitude," U.S. patent #1,703,705.