Professor Andrew Fyfe FRSE FRCSE PRSSA PRMS was a Scottish surgeon and chemist. Following early studies on Fox Talbot's newly created photographic techniques he was one of the first (1839) to work out the theory behind positive rather than negative prints. He had an amateur interest in photography but appears not to have pursued his own theories and limited his experiments to ferns lying on chemical papers.

William Gregory FRCPE FRSE FCS was a Scottish physician and chemist. He studied under and translated some of the works of Justus von Liebig, the German chemist. Gregory also had interests in mesmerism and phrenology.