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…