Correspondence, notes, journals, publications, drafts of articles and books, certificates, slides, and other material pertaining to Siegel's work in physics and ultramicroscopy, his work on his book "Modern Developments in Electron Microscopy," and with Jewish philanthropies.

Two volumes of calibration data; includes certificates and instructions for apparatus used in the Physics Department at Cornell University.

College of Engineering photographic negatives, ca. 1945-1965, unidentified; seven lantern slides of field trips, 1870-1900, identified; photographs of Physics Dept. apparatus, 1870s-1880s, identified; five glass negatives and photographs of the construction of the Hydraulic Laboratory; glass slides depicting College of Engineering equipment and facilities (1870-1900); and photographs of John McMullen with a McMullen Scholarship brochure.