According to marks on this small plastic instrument, it was “furnished” by the Sherrill Research Corporation of Peru, Indiana, and copyrighted in 1944. At that time, Sherrill was making compasses for the U.S. military and sold this calculator to easily correct compass readings. Instructions are on it.
According to a tag received with the object, Felsenthal made the instrument for the U.S. Army as the FAO-2 and sold it in 1943.
Our collection database is a work in progress. We may update this record based on further research and review. Learn more about our approach to sharing our collection online.
If you would like to know how you can use content on this page, see the Smithsonian's Terms of Use. If you need to request an image for publication or other use, please visit Rights and Reproductions.