The Man Who Proved Everest Was the World's Tallest Mountain — Without Ever Seeing It

In 1852, in a survey office in Calcutta, a 39-year-old Bengali mathematician named Radhanath Sikdar worked through a stack of trigonometric observations and arrived at a number: 29,000 feet. He had just calculated that a barely-named summit, recorded in the British survey ledgers only as "Peak XV," was the highest point on the surface of the Earth. He had never seen it. He never would.

Nepal was closed to foreigners for almost the entire 19th century, and Tibet was little more open — so no British surveyor could walk up to Peak XV, plant a theodolite nearby, and measure it directly, the way the Survey measured most Himalayan peaks. Instead, teams set up six observation stations scattered across the malarial lowlands of the Terai, in British India, each more than 150 kilometres from the mountain — the closest, at Sandakphu, still around 170 km away. Between November 1849 and January 1850, surveyors at each station recorded the tiny angle Peak XV made above the horizon. It was Sikdar's job, as the Survey's newly promoted Chief Computer, to turn those angles — plus corrections for the curvature of the Earth and the bending of light through miles of Himalayan air — into a height.

An inconvenient round number

Sikdar's arithmetic said 29,000 feet exactly. His superior, Surveyor-General Andrew Waugh, reportedly worried that a number that round would look like a rough estimate rather than a precise calculation — so he added two feet before making it official, announcing the height as 29,002 feet in March 1856. It was the first time anyone had stated, with real evidence, that this peak beat Kangchenjunga — until then assumed to be the world's highest — and every other mountain on Earth.

Waugh named the peak after his own predecessor, Sir George Everest — reportedly over Everest's own objection, since it broke the Survey's usual practice of keeping a local name where one was known. Sikdar had worked directly under George Everest for over a decade before Everest's 1843 retirement, then under Waugh; it was Sikdar's mathematics, not either Surveyor-General's, that actually found the mountain. Recognition came slowly and incompletely: an 1875 reprint of the Survey's technical manual dropped his name from chapters he had written, which one contemporary newspaper called "robbery of the dead." A German scientific society made him a corresponding member in 1864. India issued a commemorative postage stamp in his honour in 2004 — 152 years after his calculation, and long after the mountain he found had become the most famous on the planet.

Modern satellite and GPS survey work has since confirmed Sikdar right to within about 30 metres — a margin of error of roughly 0.1%, worked out with nothing but a theodolite, a notebook, and six sightlines from more than a hundred miles away.

Source: Wikipedia, cross-referenced with The Wire Science.

Cover photo: DesiBoy101 via Wikimedia Commons (CC BY 4.0).