I read a lot of history; I review a lot of history books; I read a lot of history book reviews; and I read a lot of book catalogs selling history books so not a lot slips by me. However this is a case of that happening, and I am simultaneously embarrassed (for missing it for 15 years) and overjoyed (for having discovered it.)

John Keay’s The Great Arc: The Dramatic Tale of How India was Mapped and Everest was Named (published in 2000) is the story of the Great Arc of Meridian Project. This project, envisioned by the quiet British Army surveyor William Lambton, was to survey a baseline from the tip of southern India to the Himalayan mountains. The project took most of the 19th century to complete, going on long after the death of its originator, making famous such figures as the rather obnoxious Sir George Everest. It was an overwhelming job requiring surveyors to criss cross thousands of miles of jungles, rivers, mountains and deserts, dragging along all their heavy bulky equipment. This project became the basis for the mapping of the rest of India, the laying out of infrastructure, the establishment of a tax assessment system and ultimately the means of projecting English power over the whole Indian subcontinent.

Such an overwhelming task suggests an overwhelming book, but Keay gets it all in under 200 pages. Not only does he cover the stories of the surveyors and their unsung Indian crews but he also explains the laborious process by which the the Great Arc was laid out using triangulation. The explanation of triangulation is done so well that even I (who am an absolute failure at even basic math) could understand it. He deftly explains the technical equipment used by the survey teams, including a theodolite (a tool for measuring angles) that weighed half a ton and was the height of a short man. In short, the book is a nice mix of people, places, events and easy to follow math and science. It will appeal to both history buffs and cartography enthusiasts.