 FACT: Elevations of climbable mountains werent then and arent now  determined by triangulation to known landmarks; it would have been  done by "spirit levelling," which is, more or less, a local  measuring of ones vertical change along a path from an already  established elevation which, in turn, is ultimately tied to sea  level. Elevations determined by sightings to remote landmarks, as in  this film, would be very imprecise because of atmospheric  refraction. Indeed, if such a technique could have worked, the hill  elevation could already have been determined by measurements from  the supposed reference landmarks. A resurvey of a hill that might  have turned it into a mountain would have been a differential  measurement. The surveyor would only have had to measure the  elevation change between a nearby point that he had already passed  through on the way to the summit, and the modified summit.