After the United States declared war on Germany on April 6, 1917, American leaders realized that the best optical instruments came from German shops. Thus, to obtain the spy glasses, binoculars, range finders, and other optical instruments needed by its fighting forces, they commandeered the resources of private optical and instrument shops. And they authorized the establishment of a new optical shop at the Washington Navy Yard. That facility, later termed the Naval Weapons Plant Optical Shop, gave this illuminating prism for rangefinders to the Smithsonian in 1961.
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.