The collection consists of correspondence and scientific papers of Schwarzschild which reflect his pioneering work in the use of giant balloons to hoist telescopes into the stratosphere for clearer pictures of the sun and other stars and planets. The bulk of the scientific papers is comprised of technical and engineering reports, business material, and catalogues of Stratoscope II, the second balloon system developed by Schwarzschild and his colleagues at Princeton in 1963. Also included is some material on Stratoscopes I and III and additions of academic and personal correspondence. Later additions include a glass plate negative of the great nebula in the constellation of Andromeda, a small reel of Kodakchrome movie film on the launch of the Stratoscope II balloon, and five medals (1960-1970) awarded to Schwarzschild, including the National Academy of Sciences' Henry Draper Medal of Discovery in 1960.