Great Trigonometrical Survey
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The Great Trigonometrical Survey of India was a project that aimed to carry out a survey across the Indian subcontinent with scientific precision. It was begun in 1802 by the British infantry officer
Index to the Great Trigonometrical Survey
The first triangulations across the Peninsula
Measurement of the Calcutta baseline in 1832 based on a sketch by James Prinsep. This shows surveyors stretching a chain on coffers supported on pickets. The chain is housed under shade to reduce errors due to thermal expansion, and is aligned using a boning telescope.
A zenith sector was an upward-facing telescope with accurate angle measurement scales. A star close to the zenith of known declination from the Pole Star was used to determine latitude, as a direct measurement of the Pole Star could be affected by refraction.
Survey of India
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The Survey of India is India's central engineering agency in charge of mapping and surveying. Set up in 1767 to help consolidate the territories of the British East India Company, it is one of the old
Great Trigonometrical Survey
…under the auspices of the East India Company. Under the leadership of his successor, George Everest, the project was made the responsibility of the Survey of India. Everest was succeeded by Andrew Scott Waugh, and after 1861, the project was led by James Walker, who oversaw its completion in 1871. Among the many…
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William Lambton (1753 – 19 January 1823) started Great Trigonometrical Survey (1802–1852).