Charles McCurdy "Mac" Mathias Jr. (1922-2010) was a Republican member of the United States Senate, representing Maryland from 1969 to 1987. He was also a member of the Maryland House of Delegates and the United States House of Representatives. The collection includes material from Mathias's service in both the House of Representatives and the Senate dating from approximately 1958-1988.

The collection consists of correspondence, two scrapbooks and other ephemeral material related to Gebelein's association with the Johns Hopkins University.

John Charles Geyer was as a teacher, writer, and consultant on environmental matters born in 1906. This collection consists largely of writings, subject files relating to environment consulting and teaching at Johns Hopkins University, and some personal items, spanning 1952-1980.

The Tau Beta Pi Association is the national engineering honor society. The records of the Maryland Alpha Chapter of Tau Beta Pi, a national engineering honor society, span the years 1919 to 1975.These records document the various activities Tau Beta Pi and reflect the relationship between the Maryland Chapter and the National Association, particularly since 1950.