MRA 1 tellurometer set, c 1960.
© Science Museum / Science & Society Picture Library
T L Wardley designed the tellurometer in 1957, to measure long distances over undulating countryside with an accuracy of a few centimetres in about 20 kilometres. A transmitter was set up at one end of the line and a reflector/retransmitter at the other re-radiated the mesage beam. These are master and remote instruments and accesories.