1922 Index of Great Trigonometrical Survey of India

The Great Trigonometrical Survey was a project that aimed to survey the entire

Indian subcontinent The Indian subcontinent is a physiographical region in Southern Asia. It is situated on the Indian Plate, projecting southwards into the Indian Ocean from the Himalayas. Geopolitically, it includes the countries of Bangladesh, Bhutan, India ...

with scientific precision. It was begun in 1802 by the

British infantry The Infantry of the British Army comprises 49 infantry battalions, from 19 regiments. Of these, 33 battalions are part of the Regular army and the remaining 16 a part of the Army Reserve. The British Army's Infantry takes on a variety of roles, ...

officer William Lambton, under the auspices of the

East India Company The East India Company (EIC) was an English, and later British, joint-stock company founded in 1600 and dissolved in 1874. It was formed to trade in the Indian Ocean region, initially with the East Indies (the Indian subcontinent and Sout ...

.Gill, B. (2001); "THE BIG MAN. Surveying Sir George Everest", in: ''Professional Surveyor Magazine'', Vol. 21 Nr 2. Retrieve
online
8 March 2016. Under the leadership of his successor,

George Everest Colonel Sir George Everest CB FRS FRAS FRGS (; 4 July 1790 – 1 December 1866) was a British surveyor and geographer who served as Surveyor General of India from 1830 to 1843. After receiving a military education in Marlow, Everest joined ...

, the project was made the responsibility of the

Survey of India The Survey of India is India's central engineering agency in charge of mapping and surveying.Andrew Scott Waugh, and after 1861, the project was led by James Walker, who oversaw its completion in 1871. Among the many accomplishments of the Survey were the demarcation of the British territories in

India India, officially the Republic of India ( Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the ...

and the measurement of the height of the

Himalaya The Himalayas, or Himalaya (; ; ), is a mountain range in Asia, separating the plains of the Indian subcontinent from the Tibetan Plateau. The range has some of the planet's highest peaks, including the very highest, Mount Everest. Over 10 ...

n giants:

Everest Mount Everest (; Tibetan: ''Chomolungma'' ; ) is Earth's highest mountain above sea level, located in the Mahalangur Himal sub-range of the Himalayas. The China–Nepal border runs across its summit point. Its elevation (snow ...

, K2, and

Kanchenjunga Kangchenjunga, also spelled Kanchenjunga, Kanchanjanghā (), and Khangchendzonga, is the third highest mountain in the world. Its summit lies at in a section of the Himalayas, the ''Kangchenjunga Himal'', which is bounded in the west by the T ...

. The Survey had an enormous scientific impact as well, being responsible for one of the first accurate

measurements Measurement is the quantification of attributes of an object or event, which can be used to compare with other objects or events. In other words, measurement is a process of determining how large or small a physical quantity is as compared ...

of a section of an arc of

longitude Longitude (, ) is a geographic coordinate that specifies the east– west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek let ...

, and for measurements of the geodesic anomaly, which led to the development of the theories of

isostasy Isostasy (Greek ''ísos'' "equal", ''stásis'' "standstill") or isostatic equilibrium is the state of gravitational equilibrium between Earth's crust (or lithosphere) and mantle such that the crust "floats" at an elevation that depends on it ...

. The native surveyors made use of in the Himalayas, especially in

Tibet Tibet (; ''Böd''; ) is a region in East Asia, covering much of the Tibetan Plateau and spanning about . It is the traditional homeland of the Tibetan people. Also resident on the plateau are some other ethnic groups such as Monpa people, ...

(where Europeans were not allowed), were called

pundit A pundit is a person who offers mass media opinion or commentary on a particular subject area (most typically politics, the social sciences, technology or sport). Origins The term originates from the Sanskrit term ('' '' ), meaning "knowledg ...

s, who included the cousins

Nain Singh Rawat Nain Singh (21 October 18301 February 1882), also known as Nain Singh Rawat, was one of the first Indian explorers (dubbed "pundits") employed by the British to explore the Himalayas and Central Asia. He came from the Johar Valley in Kumaon. ...

and

Krishna Singh Rawat Rai Bahadur Kishen Singh or Krishna (1850–1921) was a native Indian explorer, termed a ''pundit'' by the British, who was employed by the Survey of India. His code-name was 'A.K.' and his accomplishments would rival those of his famous cousin ...

.Peter Hopkirk, 1982, "Trespassers on the Roof of the World: The Race for Lhasa",

Oxford University Oxford () is a city in England. It is the county town and only city of Oxfordshire. In 2020, its population was estimated at 151,584. It is north-west of London, south-east of Birmingham and north-east of Bristol. The city is home to the ...

Press.Derek J. Waller, 2004,
The Pundits: British Exploration of Tibet and Central Asia
" University Press of Kentucky.Account of the Pundit's Journey in Great Tibet - Capt. H. Trotter, The Journal of the Royal Geographical Society (1877).

History

From its inception in 1600 to its domination of the entire

by the beginning of the nineteenth century, the

British East India Company The East India Company (EIC) was an English, and later British, joint-stock company founded in 1600 and dissolved in 1874. It was formed to trade in the Indian Ocean region, initially with the East Indies (the Indian subcontinent and Southea ...

gained more and more territory. With the acquisition of new territory, it employed several explorers and cartographers to provide maps and other information on its territories, most notably

James Rennell Major James Rennell, (3 December 1742 – 29 March 1830) was an English geographer, historian and a pioneer of oceanography. Rennell produced some of the first accurate maps of Bengal at one inch to five miles as well as accurate outlines of I ...

, from 1767 in

Bengal Bengal ( ; bn, বাংলা/বঙ্গ, translit=Bānglā/Bôngô, ) is a geopolitical, cultural and historical region in South Asia, specifically in the eastern part of the Indian subcontinent at the apex of the Bay of Bengal, predom ...

. As Rennell proceeded to make maps, the lack of precise measurement was noticed. In 1800, shortly after the Company victory over

Tipu Sultan Tipu Sultan (born Sultan Fateh Ali Sahab Tipu, 1 December 1751 – 4 May 1799), also known as the Tiger of Mysore, was the ruler of the Kingdom of Mysore based in South India. He was a pioneer of rocket artillery.Dalrymple, p. 243 He in ...

, William Lambton, an infantry soldier with experience in surveying, proposed to remedy precisely that, through a series of

triangulation In trigonometry and geometry, triangulation is the process of determining the location of a point by forming triangles to the point from known points. Applications In surveying Specifically in surveying, triangulation involves only angle ...

s, initially through the newly-acquired territory of

Mysore Mysore (), officially Mysuru (), is a city in the southern part of the state of Karnataka, India. Mysore city is geographically located between 12° 18′ 26″ north latitude and 76° 38′ 59″ east longitude. It is located at an altitude of ...

, and eventually across the entire

subcontinent A continent is any of several large landmasses. Generally identified by convention rather than any strict criteria, up to seven geographical regions are commonly regarded as continents. Ordered from largest in area to smallest, these seven ...

The Great Trigonometrical Survey of India started on 10 April 1802 with the measurement of a baseline near

Madras Chennai (, ), formerly known as Madras (List of renamed Indian cities and states#Tamil Nadu, the official name until 1996), is the capital city of Tamil Nadu, the southernmost states and territories of India, Indian state. The largest city ...

. Major Lambton selected the flat plains with St. Thomas Mount at the north end and Perumbauk hill at the southern end. The baseline was long. Lieutenant Kater was despatched to find high vantage points on the hills of the west so that the coastal points of Tellicherry and Cannanore could be connected. The high hills chosen were Mount Delly and Tadiandamol. The distance from coast to coast was and this survey line was completed in 1806. The East India Company thought that this project would take about five years, but it took nearly 70 years, well past the

Indian Rebellion of 1857 The Indian Rebellion of 1857 was a major uprising in India in 1857–58 against the rule of the British East India Company, which functioned as a sovereign power on behalf of the British Crown. The rebellion began on 10 May 1857 in the fo ...

and the end of

company rule in India Company rule in India (sometimes, Company ''Raj'', from hi, rāj, lit=rule) refers to the rule of the British East India Company on the Indian subcontinent. This is variously taken to have commenced in 1757, after the Battle of Plassey, whe ...

. Because of the extent of the land to be surveyed, the surveyors did not triangulate the whole of India but instead created what they called a "gridiron" of triangulation chains running from north to south and east to west. At times the survey party numbered 700 people. The Trigonometrical Survey was conducted independently of other surveys, notably the topographical and revenue surveys. In 1875, the decision was taken that the Survey budget should be reduced from 240,000 to 200,000 pounds. This resulted in a reorganization under Surveyor-General Colonel J.T. Walker to amalgamate the Great Trigonometrical, Topographical and Revenue Surveys into the Survey of India.

Instruments and methods used

Triangulation surveys were based on a few carefully measured baselines and a series of angles. The initial baseline was measured with great care since the accuracy of the subsequent survey was critically dependent upon it. Various corrections were applied, principally temperature. An especially accurate

folding chain Gunter's chain (also known as Gunter’s measurement) is a distance measuring device used for surveying. It was designed and introduced in 1620 by English clergyman and mathematician Edmund Gunter (1581–1626). It enabled plots of land to be ac ...

was used, laid on horizontal tables, all shaded from the sun and with constant tension. The early surveys made use of large and bulky

theodolite A theodolite () is a precision optical instrument for measuring angles between designated visible points in the horizontal and vertical planes. The traditional use has been for land surveying, but it is also used extensively for building and ...

s made by William Carey, a Zenith sector made by

Jesse Ramsden Jesse Ramsden FRS FRSE (6 October 1735 – 5 November 1800) was a British mathematician, astronomical and scientific instrument maker. His reputation was built on the engraving and design of dividing engines which allowed high accuracy measureme ...

and chains. Later surveys used more compact theodolites. Survey_towers_GTS

Great Trigonometrical Survey Tower - Sukchar - North 24 Parganas 2012-04-11 9482

Accurate instruments could not always be purchased through the standard system of government contract and Everest personally supervised the construction of instruments. He had a maker, Henry Barrow, set up an instrument company in Calcutta. Barrow was succeeded by Syed Mohsin from Arcot, Tamil Nadu, and after his death, the instruments were supplied by Cooke from

York York is a cathedral city with Roman Britain, Roman origins, sited at the confluence of the rivers River Ouse, Yorkshire, Ouse and River Foss, Foss in North Yorkshire, England. It is the historic county town of Yorkshire. The city has many hist ...

Correcting deviations

To achieve the highest accuracy a number of corrections were applied to all distances calculated from simple trigonometry: *

Curvature of the earth Spherical Earth or Earth's curvature refers to the approximation of figure of the Earth as a sphere. The earliest documented mention of the concept dates from around the 5th century BC, when it appears in the writings of Greek philosophers. ...

* The non-spherical nature of the curvature of the earth * Gravitational influence of mountains on

pendulum A pendulum is a weight suspended from a wikt:pivot, pivot so that it can swing freely. When a pendulum is displaced sideways from its resting, Mechanical equilibrium, equilibrium position, it is subject to a restoring force due to gravity that ...

s and plumb lines *

Refraction In physics, refraction is the redirection of a wave as it passes from one medium to another. The redirection can be caused by the wave's change in speed or by a change in the medium. Refraction of light is the most commonly observed phenomen ...

Height above mean sea level Height above mean sea level is a measure of the vertical distance (height, elevation or altitude) of a location in reference to a historic mean sea level taken as a vertical datum. In geodesy, it is formalized as ''orthometric heights''. The co ...

Superintendents

*1818–1823 – William Lambton *1823–1843 – Sir George Everest *1843–1861 – Andrew Scott Waugh *1861–1883 – James Thomas Walker *1884–1888 – C. T. Haig *1888–1894 – George Strahan *1894–1899 –

St George Corbet Gore Colonel St George Corbet Gore, (24 February 1849 – 1913) was an English army officer and Surveyor General of India from 1899 to 1904. Gore was born on 24 February 1849, the son of Rev. William Francis Gore, a male-line descendant of the Gore ...

*1899–1911 – Sidney Gerald Burrard *1912–1921 – Sir Gerald Ponsonby Lenox-Conyngham

References

External links

{{commons category * 1802 establishments in British India

Geodetic surveys Geographic history of India Surveying of India 19th century in India