Christian James (C. J.) Lambertsen (1917-2011) worked as a professor of pharmacology, director of the Institute for Environmental Medicine, and the founding director of the Environmental Biomedical Stress Data Center in 1985 at the University of Pennsylvania's School of Medicine. He designed the Lambertsen Amphibious Respiratory Unit (LARU), which was the first widely used, closed-circuit Self-Contained Underwater Breathing Apparatus (SCUBA) in the United States. Types of materials include correspondence, reports, photographs, audio material, slides, lab books, lab data, experimental measures and procedures, diagrams, graphs, articles, manuscript drafts, grant proposals, newspaper clippings, and notes. Primary subjects include decompression, oxygenation, diving, decompression sickness, diving physiology, and underwater breathing apparatus. Materials range in date from 1930 to 2004.