This is about surveying—specifically, about a major surveying project with a lofty goal and some unexpected results.
In 1802, the East India Company authorized the “Great Trigonometric Survey.” Its aim was to define a meridian (north-south measuring line) and baseline (east-west measuring line) that could be used to survey all of India. Eventually this task would bankrupt the company. They thought it would take 5 years. It took over 60. When finished, the principal meridian was over 1,400 miles long.
By the 1830s, the surveyors had reached the foothills of the Himalayas and began to estimate the heights of the taller peaks. In 1847, one peak caught the attention of a surveyor because it appeared to be taller than Kangchenjunga, then believed to be the world’s tallest mountain. Averaging out a series of measurements and accounting for atmospheric distortion gave a height of 29,000 feet exactly, which was announced to be 29,002 feet to keep people from assuming the measurement was approximate.
These measurements were carried out anywhere from 108 to 140 miles away from the summit of Everest. The distance to Everest was calculated using trigonometry based on the angles and distances between the measuring points and the meridian. The elevations of the individual measuring points themselves were based on countless estimates of elevation performed during the survey of the meridian.
(Everest as seen from India)
In testimony to the accuracy of those hundreds of measurements, the estimated height of Everest using modern technology is only .1% higher than the 1857 estimate.
By the way, George Everest did not want this mountain named after him. He preferred the use of local names.
Read More: The Great Arc