Manuscripts, research notes, correspondence, reprints, and patents of Ralph V. L. Hartley. The manuscripts, research notes, and the majority of the correspondence cover such topics as wave mechanisms, classical electromagnetic theory, a mechanical system of theoretical physics, rotational ethers, McCullagh ethers, and relativistic classical ethers. The collection reflects little of the scientific and technological activity for which Hartley is known, instead dealing with Hartley's theoretical research from the later 1920s until his death. His various attempts to defend a classical mechanistic view of physical phenomena and to discard relativity theory and quantum mechanics are well documented, as is his often frustrating effort to find a audience in the official community of physicists and philosophers of science. Correspondents include David Bohm, Louis de Broglie, Charles W. Churchman, Lloyd Espenschied, Samuel A. Goudsmit, Herbert E. Ives, Henry Margeneau, Thomas Marshall, Marvin G. Moore, Harry Nyquist, John T. Tate, and Carl Wiley.