Holding two degrees in Aeronautical Engineering, Dr John E Hesselgreaves has had many years' experience in fan and pump design and heat transfer research, and has taught Thermodynamics at Heriot-Watt University and the University of Glasgow. He has authored many papers in Heat Transfer and has published a specialist book on Compact Heat Exchangers (Elsevier, 2001). His current technical interests are in aircraft propulsion and enhanced heat transfer surfaces, and in the latter he acts as an industrial consultant. He has had many years' experience on church vestries, and on leading house groups...