Conical Prism

Unknown artist

This is a conical glass prism mounted on a brass base that, in turn, would fit on an optical bench. The “J. DUBOSCQ / A PARIS” inscription refers to Jules Duboscq (1817-1886), an optical instrument maker who began working on his own in the early 1850s, and who noted that this instrument produced a circular spectrum. This item was used by cadets at the U.S, Military Academy.