The control panel of the MRA2 Tellurometer It was in the late 1950s that the Tellurometer hit the surveying profession. Certainly it was not the first EDM instrument on the market, that title goes to the Geodimeter which appeared in 1947, but there was a difference. The Geodimeter worked on a light source and as such its maximum range was limited by visibility. The Tellurometer operated on a radiowave which could penetrate most weather conditions and achieved distances up to 100 miles. Since the early 1900s any long distance that was required to be measured as accurately as possible, e.g. a survey baseline, was determined using long tapes or wires suspended in catenary. Numerous baselines around the world were measured this way with each requiring 20 to 40 personnel over a period of several weeks. Then, suddenly, the profession had new tools that would allow such a task to be completed in 20 minutes by two persons. It was a revolution that completely changed the manner in which surveying operated.