This is a quartz prism from a small Cornu-prism ultraviolet spectrograph designed and built about 1943 to be flown from Peenemuende aboard a rocket. The German physicist Erich Regener had arranged to construct an instrument package for the A-4 ballistic missile, later renamed V-2, to measure temperature, pressure and density of the atmosphere at rocket heights. The instruments included an ultraviolet spectrometer that would determine the distribution of ozone at high altitude by measuring its absorption using the sun as background illumination. Data were to be recorded photographically and recovered after landing. Regener was probably picked for this contract work because he was the most prominent German physicist exploring the upper atmosphere with balloon-borne instruments. The war ended before the instrument package could be flown. These spectrometer parts were donated to NASM by Dr. Ernst Stuhlinger, a participant in the V-2 program, who brought them to this country when he was recruited by the U.S. Army in 1945.