The Great Survey Saga – Part -II

The Great Arc


In the pre-computer age, the concept of trigonometry and triangulation was pretty hard to grasp, even though the basic principle is simple: Assume that you know the exact distance between points A and B (AB) in the triangle ABC. Then, you can further assume that by measuring the angles CAB and CBA, you can calculate the distance AC and BC. AC and BC is accepted as baselines (for further measurements). If you extend this method to generate huge web of triangles across the country, then you have exact distances. Really simple isn’t? Yeah, only in paper. Further, the measurement gets tricky, in surveying hills and depressions.

Lambton measured base lines during March 1806 at Coimbatore, 1808, at Tanjore (the top of Brihadeshwara Temple was chosen to form the apex of the triangle. During the process theodolite fell and crashed into the gopuram (tower). The theodolite was damaged but the sculptures seemed to have survived. On 1809 it was at Palayamkottai, 1810 and 1811 at Ooty. The area covered by the trigonometrical operations during Colonel Lambton‘s aggregated 165, 342 square miles. He was also had to make his way up in the face of adverse criticism. He was forced several times to demonstrate the scientific validity and utility of his work before both administrators and scientists.



The Great Trigonometrical Survey

After Lambton’s death in January 1823, George Everest continued the programme in carrying out the great arc northwards in difficult tracts. In 1862, after 60 years, the “Great Indian Arc of the Meridian” was established. To put it simply, the result was map of India as we see it today.

The hardships in conducting this survey were immense: Infectious diseases, wild animals, unpassable rivers, and hostile local people. According to one account, the lives lost during this survey surpassed the mortalities in the wars of 19th century India.

Still, there is one question, which needs to be answered: Why the British geologists were resolutely determined to conduct this project? Mackenzie (the man who surveyed Mysore) and Lambton fought in the Anglo-Mysore war and defeated Tippu Sultan. With that defeat, the British considered that it is high-time for East India Company to control rest of India. It was essential for them to have a complete geographical knowledge of the country for their revenue and administrative purposes.

The purpose might have paralleled British’ forces military success, but still the survey seems significant.  The surveyors contributed enormously in enriching the knowledge about our country. The next time you see an Indian map, remember the sacrifices of Lambton, Everest, Waugh, Walker, Radhanath and thousands of unknown heroic workers.

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