Copy letter from Herbert Rix, to Dr Archibald Geikie, Foreign Secretary of the Royal Society Rix states that Dr Hugo Müller suggests that Mr Allan [Brugh] Dick's microscope with spectroscopic arrangement for the examination of minute crystals of minerals would be suitable for a Soirée exhibit. Müller says that Geikie will know about the matter, and that Dick often works at Jermyn Street. Rix asks that Geikie assist in providing his address or getting the exhibit sent. 16 April 1891