Correspondence and manuscripts. The collection (bulk dates 1900-1938) offers a wealth of sources on early physics history, in particular, radium research and the life and personality of Stefan Meyer. It contains some 2300 items of correspondence with over 400 correspondents around the world, including 35 Nobel prize winners. Also contains 95 manuscripts of contributors from all over the world to a Festschrift on the occasion of Ludwig Boltzmann's 60th birthday. Correspondents include Ernest Rutherford, Frederick Soddy, William Ramsay, Otto Hahn, and Bertram Boltwood.