Professor Arthur Frederick Brown, a Fellow of the Royal Society of Edinburgh for over fifty years, died on 9 October 2014 aged ninety-four. He was born in 1920 in Castle Douglas. In 1938 he was dux of Kirkcudbright Academy and then went to Edinburgh University where he did a degree in Natural Philosophy, graduating with first class honours and the Gold Medal in 1942. He was recruited by Professor Simon of Oxford University to work on the early development of atomic energy, particularly relating to the separation of uranium isotopes. After the war he held several fellowships at the Cavendish Laboratory in Cambridge. In 1952 he was appointed to a lectureship in Physics at Edinburgh University, where he thrived, setting up a research group on the physics of metals and issuing a steady stream of publications using his knowledge of radioactive isotopes to study surface and defect properties by diffusion. This work earned him a readership. In 1967 he accepted a chair in Physics at the City University in London, where he was able to bring in external funding and maintain a substantial research group working mainly on non-destructive testing. A notable achievement was the work on ultrasonic surface wave modelling for crack detection, supported by innovative transducer development. One of his research interests had been the failure of metallic surgical implants and perhaps this led him to his decision to leave his body to medical science. Elected to the Royal Society of Edinburgh in 1959, Professor Brown served on the RSE Council from 1963-67. He is survived by his wife Margaret and his son and daughter.