The papers, which are substantial, deal almost exclusively with Appleton's scientific work. There is little personal or private correspondence and almost no surviving material, apart from lectures, speeches and addresses, relating to his public life as scientific administrator or university principal. There are, however, a good run of diaries and engagement books and extensive folders of notes, research ideas, manuscript calculations and data from all periods of Appleton's career, as well as much additional data contributed by assistants or from observatories. The correspondence includes an extended exchange of letters with B. van der Pol, 1921-1924, on oscillations and non-linearity, and long and frequent exchanges with long-term friends and collaborators such as W.J.G. Beynon, R. Naismith and W.R. Piggott. Appleton's collection of reprints, preprints and limited circulation reports also includes some important items.