Comprises: Papers relating to the coherer, c. 1897-1903 Papers concerning the magnetic detector, 1902-6 Papers concerning the Poulsen system and the Poulsen and Duddell arcs, 1906-28 Letter from I. Bowden reporting his satisfactory testing of instruments including coils, keys, receivers, inkers and jiggers, 1900 Annotated diagrams by…