Dr Barrie Colvin is a specialist the chemistry and physics of polymers, having graduated with a doctorate degree from the University of Manchester. He worked as a senior research scientist for Shell Chemicals and now runs his own company. Barrie has been involved with the physical aspects of psychical research for over forty years. He has been active in the investigation of mental and physical mediums, including direct-voice, transfiguration and materialisation mediumship. Other projects have included include haunted houses, the human aura, and the evaluation of evidence in psychic detection cases. His principal interest recently has been the physics of poltergeist activity: he has developed new instruments to aid investigation and carried out a study of the acoustic properties of unexplained rapping sounds.