Land of seven rivers: History of India's Geography

by Sanjeev Sanyal

Despite everything, Mandeville’s book had a very profound impact on the history of the world. He claimed that his travels had proved that the world was round and his book popularized the idea that it was possible to reach India by sailing west. Columbus planned his 1492 expedition after reading The Travels, and explorers like Raleigh read the book very carefully. Thus, one of the greatest discoveries of history was based on an elaborate lie!

It was during the campaign that Lambton came up with the idea of doing a survey of India using triangulation. Basically, this requires three mutually visible points as corners of a triangle. If one knows the length of any of the sides and can measure the angles, the length of the other sides can be established by trigonometry. The newly determined sides can then each be used to establish a new triangle and so on. It is tedious work but provides very accurate measurements. Lambton had another motive beyond just creating an accurate map of India. Using this methodology, he wanted to also use the measurements to establish the exact shape and curvature of the earth. This was not just scientific curiosity; it was of vital importance to a naval and commercial power like Britain. Lambton told Arthur Wellesley his plan, who in turn spoke to his brother the Governor General. Lambton got the job. The first thing that Lambton did was to order a state-of-the-art theodolite to help with the survey. A theodolite is basically a telescope that has been specially adapted to allow the very accurate measurement of angles needed for triangulation. The equipment Lambton ordered weighed half a ton and had to be shipped from England. On the way it was captured by the French and taken to Mauritius. However, when the French realized that it was a scientific instrument, they gallantly repacked and sent it to Madras. At last, Lambton could start on his work. Lambton began by establishing a baseline ...