Correspondence, manuscripts, notes, notebooks, diaries, photographs, lantern slides, printed ephemera, and books documenting Willard Leslie Severinghaus' career in the field of physics (thermodynamics and electricity), as well as exceedingly rich documentation of a personal/business trip to Europe in 1927 with his wife, Frances Orr Severinghaus. The cataloged correspondence includes letters from: Richard Bentley; Nicholas Murray Butler; Albert Einstein; A.A. Michelson; Charles Montagu, 1st Earl of Halifax; Robert Oppenheimer; John William Strutt, third Baron Rayleigh; and August Weismann. His own correspondence files consists of letters from family and friends, professional correspondence with international colleagues; letters to his wife and the Orr family in 1927, from Europe, letters of condolence to Frances Orr Severinghaus on his death, and his last will and testament of 1927.

Manuscript files include teaching notes and student lists; notebooks on physics, experiments, etc.; college notebook on biology and Willard Leslie Severinghaus notebooks and Frances Orr Severinghaus diary of their trip to Europe in 1927. Teaching materials, American Physical Society, lightning, Moores Hill College, and telephotographs are included in the subject files. Biographical information includes the wedding announcement of Willard Leslie Severinghaus and Frances Orr; his obituary and letters relevant to his wife's teaching appointments. There are photographs of Severinghaus, his family, other scientists, laboratory equipment, one identified group photograph of the "Cavendish Research" in 1926, 24 lantern slides (3 1/4 x 4 inches, glass) which appear to be a specially ordered lecture set on lightning and six slides for a lecture on thermodynamics. There is also a 75 item, A-Z student name and quiz grade card file, and 17 books from his library.