Scope and Contents: Large number (approx. 2,000) of 6 x 6, 9 x 12 and 8 x 8 cm slides used in lectures given by Niels Bohr and others at the Niels Bohr Institute. Topics include: optical spectra; X-rays and interference phenomena; atomic theory; isotopy; nuclear physics; fission; particle physics; apparatus for nuclear physics including, for example: cloud chamber, cyclotron, Van de Graaff generator. The collection is not catalogued.