These files were collected in 1939, as part of Mildred Howie's research for a student paper on cyclotrons. The files include 6 letters, 2 article reprints, and one student paper titled "Cyclotron." Correspondents include: Kenneth T. Bainbridge, Harvard University; James Chadwick, University of Liverpool; L.A. (Lee Alvin) DuBridge, University of Rochester; John R. Dunning, Columbia University; and R.C. (Roswell Clifton) Gibbs, Cornell University. Some of the files include photographs of cyclotrons. All photographs were removed to the Emilio Segre Visual Archives; photocopies of the images remain in the collection.