In 1749 the British ‘Survey of India’ identified a lofty peak in the distant ranges of the Himalayas. It was called Peak XV, but it was not until 1849 that another survey set out to measure its height. When the survey was completed in 1852 it was confirmed that Peak XV was the highest mountain in the world.
Various names were suggested for it, including Devadhunga (Throne of Gods) and Guarishankar (Gleaming White Bride of Shiva). The Tibetans call it Chomolungma (Goddess Mother of the World). But the name approved by the Royal Geographical Society in London was suggested by Andrew Waugh, then Surveyor General of India. He thought it should be named after his predecessor – Sir George Everest.
Classical surveying techniques were used to calculate Everest’s height. First of all a baseline several miles long was measured along the ground at a known elevation above sea level. The top of the mountain could be seen from both ends of the line, and bearings were taken to the peak with theodolites – instruments which accurately measure angles.
From a knowledge of two angles and the length of one side of a triangle, the lengths of the other sides can be worked out – giving the distance of the peak from the baseline. Further calculations can then give the height. The surveyors measured Everest from six different sites – producing six figures ranging between 28,990 and 29,026ft (8836 and 8847m). The average came to exactly 29,000ft (8839m) – but because it sounded like an approximation they added 2ft (0.6m), and produced their authoritative answer – 29,002ft (8840m).
Everest’s position as the world’s highest mountain went unquestioned until 1986, when George Wallerstein, from the University of Washington, using a different method, claimed that another Himalayan mountain, K-2, might be 36ft (11m) higher.
Wallerstein’s claim was so startling that an Italian expedition visiting the Himalayas in 1987 decided to check it. They placed receivers part-way up Everest and K-2, and used Navstar signals to establish their exact height of the baseline on which calculations are based.
The team, led by geologist Ardito Desio, then calculated the heights of the two mountains using theodolites set up on the receivers’ positions. Their conclusion was that Wallerstein was wrong: Everest was measured at 29,108ft (8872m), a full 840ft (256m) higher than K-2.
Picture Credit : Google