Why in the News?

This newscard highlights the role of Indian assistants in completing the Great Trigonometric Survey (GTS), which began in 1802 to map India’s geography.

About the Great Trigonometrical Survey (GTS):

• Launch and Objective: The GTS was a massive scientific and cartographic initiative launched in 1802 by the British to map India with unprecedented precision using trigonometry and geodesy.
• Initiator: It was conceptualised by William Lambton, a British army officer, and carried out under the East India Company.
• Purpose: It aimed to measure Earth’s curvature, create accurate maps, and support colonial administration, scientific research, and military planning.
• Survey Method: It used triangulation, involving a network of interconnected triangles built from a known baseline to calculate distances and angles over large areas.
• First Baseline: The initial baseline was measured in 1802 at St. Thomas Mount near Madras (Chennai) and extended over 2,600 km up to the Himalayas.
• Instruments Used: The survey used massive theodolites (weighing up to half a ton) and measuring chains, requiring large teams for operation and transport.
• Scientific Outcome: It led to the formulation of the Everest Spheroid, a geodetic reference model still used for mapping in South Asia.
• Duration and Leadership: Although planned to take 5 years, the project lasted nearly 70 years (until 1871) and was led by successors such as George Everest (after whom Mt. Everest was named), Andrew Scott Waugh, and James Walker.

How did the GTS led to the Mapping of India?

• First Accurate Maps: It provided scientific maps that corrected earlier errors, enabling modern geodetic frameworks for administration and infrastructure.
• Survey Range: It mapped from southern India to the Himalayas, supporting large-scale development and scientific measurement.
• Great Arc Measurement: It measured the Great Arc (Chennai to Dehradun), a significant geodetic arc that helped calculate Earth’s curvature.
• Himalayan Heights: Using triangulation data, the survey measured 79 Himalayan peaks, including Mount Everest, K2, and Kangchenjunga.
• Mount Everest Identification: In 1852, Peak XV was identified as the world’s highest mountain, later named Mount Everest in honour of George Everest.
• Latitude-Longitude System: It produced precise longitude and latitude coordinates, crucial for navigation, military logistics, and administration.
• Infrastructure Impact: Survey benchmarks supported railways, roads, canals, and earthquake studies, many of which remain relevant today.

Contribution of Indians to the GTS:

• Syed Mir Mohsin Husain: A jeweller from Arcot who repaired critical instruments and was later appointed as an instrument maker in the Surveyor General’s office.
• Radhanath Sikdar: An Indian mathematician who calculated the height of Mount Everest in 1852, confirming it as the tallest peak globally.
• Indian Field Workers: Thousands of Indian flagmen, khalasis, and labourers undertook challenging tasks like carrying heavy equipment, setting markers, and working in hazardous environments.
• Logistical Support: Indian artisans and technicians repaired, calibrated, and adapted instruments, making the project feasible under Indian conditions.
• Role of Pundits: Trained Indian “pundits” conducted secret surveys in Tibet and politically sensitive regions, where British officers were restricted.

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