The Great Arc

The Great Indian Arc of the Meridian, begun in 1800, was the longest measurement of the earth's surface ever to have been attempted. Its 1600 miles of inch perfect survey took nearly fifty years, cost more lives than most contemporary wars, and involved equations more complex than any in the pre-computer age. Hailed as 'one of the most stupendous works in the history of science', it was also one of the most perilous. Through hill and jungle, flood and fever, an intrepid band of surveyors carried the Arc from the southern tip of the Indian subcontinent up into the frozen wastes of the Himalayas. William Lambton, an endearing genius, had conceived the idea; George Everest, an impossible martinet, completed it. Both found the technical difficulties horrendous. With instruments weighing half a ton, their observations had often to be conducted from flimsy platforms ninety feet above the ground or from mountain peaks enveloped in blizzard. Malaria wiped out whole survey parties; tigers and scorpions also took their toll.

Yet the results were commensurate. The Great Arc made possible the mapping of the entire Indian subcontinent and the development of its roads, railways and telegraphs. India as we now know it was defined in the process. The Arc also resulted in the first accurate measurements of the Himalayas, an achievement which was acknowledged by the naming of the world's highest mountain in honour of Everest. More important still, by producing new values for the curvature of the earth's surface, the Arc significantly advanced our knowledge of the exact shape of our planet.

"More extraordinary than any fiction."
CHARLOTTE CORY, MAIL ON SUNDAY

"A triumph."
ANDREW TAYLOR, LITERARY REVIEW

"This wonderful book – surely Keay's most compelling, and one of the most remarkable works of non-fiction to be published this year – is a fitting monument not just to Everest but also to the Great Arc itself."
WILLIAM DALRYMPLE, SUNDAY TIMES