How Five Men Measured Mount Everest — The Six‑Decade Quest to Find the World's Highest Peak

How Five Men Measured Mount Everest

Summary: The identification of Mount Everest as the world’s highest mountain was not a single dramatic discovery but the result of decades of painstaking surveying by the British Survey of India. Beginning with a coastal baseline in 1802 and ending with detailed computations and publication in the 1850s, five central figures played distinct and indispensable roles.

From a Coastal Baseline to a Continental Survey

On 10 April 1802 Lieutenant William Lambton of the East India Company began measuring what would become one of surveying’s most celebrated baselines: a little over 12 km between St. Thomas Mount and Perumbauk, using a 30.48 m steel chain compensated for temperature. Lambton’s team measured each section three times in each direction and achieved a final probable error under 5 cm. From this single baseline he began the Great Trigonometrical Survey — a chain of triangles intended to span from Cape Comorin to the Himalayan snows.

Discipline and Instruments: George Everest

Sir George Everest (1790–1866) inherited Lambton’s project and transformed it into a model of methodological rigor. Appointed superintendent of the Great Arc in 1823 and Surveyor General in 1830, he raised standards: discarding unreliable triangles, introducing compensation bars for thermal expansion, insisting on multiple-night angle observations, and requiring at least two independent observers at each station. He also supervised the use of the massive Great Theodolite (nearly 1.5 m tall, with a 1 m horizontal circle and an accuracy to one second of arc), an instrument so large it sometimes needed 30 porters or even elephants to move.

Fieldwork in the Terai: James T. Nicolson

The final field phase that made measuring the highest peaks possible took place from the Terai — a malarial belt at the Himalayan foot — because Nepal was closed to Europeans. In the winters of 1849–51, Captain James T. Nicolson led parties that erected 20–30 m bamboo towers and observed faint angular rays to distant peaks (usually 160–190 km away). Nicolson selected key stations (including Sandiakaphu) and recorded thousands of angle measurements under difficult and dangerous conditions. The work exacted a terrible toll on his health; he later died young, but his field books survived.

Computing the Heights: Radhanath Sikdar

At the computing offices in Mussoorie and Dehradun, Indian 'computers' converted Nicolson’s raw angles into heights. Radhanath Sikdar (1813–1870), a gifted mathematician recruited to the Survey, led these reductions as Chief Computer. The calculations required corrections for instrumental error, temperature and pressure, Earth curvature, atmospheric refraction (which could change readings by several minutes of arc), and even the gravitational deflection caused by the Himalayan mass. Using seven‑figure logarithms and laborious hand reductions, Sikdar concluded in 1852 that Peak XV was about 150 m higher than Kangchenjunga and very near 8,839 m above the mean sea level at Calcutta.

Verification and Announcement: Andrew Waugh

Andrew Scott Waugh, Surveyor General and Everest’s former deputy, insisted on exhaustive checks: new observations, re-measurements, and independent recomputations. After careful verification he published the height as exactly 8,839.8 m in a March 1856 letter to the Royal Geographical Society and proposed naming Peak XV Mount Everest. George Everest, then living in England, expressed a preference for a native name but accepted the decision politely.

"It was not the triumph of a single person but of a long chain of skilled men and rigorous methods."

Refinements and Modern Measurements

The 8,839.8 m figure stood as the official height for nearly a century, with small refinements in the early 20th century and the 1950s. Later advances — closer theodolite triangulation, photogrammetry, satellite geodesy, GPS and gravimetry, and the convention to measure to the top of the permanent snow cap — produced the modern consensus of 8,848.86 m (China–Nepal joint announcement, 8 December 2020).

Legacy

The discovery of Everest’s height was the product of six decades of institutional skill: from Lambton’s steel chain in 1802, Everest’s methodological overhaul, Nicolson’s hazardous fieldwork, Sikdar’s rigorous computations, to Waugh’s painstaking verification and publication. Each role was essential to turning scattered observations into a world‑changing geographic fact.

Further Reading: John Keay, The Great Arc.