In the plains of the delta region of what was then Tanjore district, two centuries ago, when the biggest exercise of manual land survey was being undertaken, the three-foot tall, half-tonne behemoth of an instrument — ‘the great theodolite’, suffered an injury. The instrument, used to measure angles, took a great fall as one of the ropes meant to hoist it atop the 217-foot gopuram of the Brihadeeswarar temple snapped, falling and coming to pieces. But the shattering of the instrument didn’t deter William Lambton, the man instrumental in mapping the vast expanse of the country.
Read: Call to Add Trigonometric Survey In College Syllabus in Chennai Exactly 213 years ago, two ‘compaswallahs’ – the slang used for surveyors in the 19th century, Lambton and George Everest set out on a feat to measure the earth’s curvature and map India. But today, not many are aware of it. |
The accident to the great theodolite was just a small hiccup in the Great Trigonometric Survey or The Great Arc, the beginning of which saw its 213rd anniversary on Friday. Starting with a baseline of 7.5 miles at Saint Thomas Mount, the survey then moved to Cape Comorin (Kanyakumari) and then extended all the way to the heights of what is now Mount Everest, later travelling north to Kashmir.
Employing the method of triangulation, the company under Lambton’s helmsmanship dissected a part of country with triangles, using standard 100-foot chains, a motley crew of natives, load-carrying animals and a massive reserve of will.
Triangulation involves starting with measurement between two points, which then becomes the baseline. Once this is done, the angles and then subsequently the distance to a third reference point can be calculated using a theodolite. And Lambton used this method coming up with what is still considered accurate and one of the six greatest events of the era. “When you conquer a country, you want to know what there is in it, you want to know the shape of the land,” says S Muthiah, Madras chronicler.
Today, 213 Years Ago Began the Epic Survey That Sized up India From a spot on top of St Thomas Mount on April 10 began an epic 2,400 km journey that mapped the ends of the country. |
In 1799, Mysore Maharaja Tippu Sultan was defeated by Arthur Wellesley-led East India Company forces, following which a series of surveys were undertaken, including the topographic survey led by Colin Mackenzie who eventually became Surveyor General in 1815 and the Trigonometric Survey of the Indian Peninsula.
During this period, Madras was the most important city in India and major landmark events had their beginnings here, says Muthiah. The GTS too had its roots in the port city.
Herculean task
The physical difficulties of the survey that were braved by the troops boggles the mind of historians and surveyors even today, when sophisticated technology, air-conditioned vehicles and GPS have made processes simpler.
When the government of Madras sanctioned Lambton’s survey, he put together a company that spent weeks in the forests, months to clear vegetation in the hills to set up stations , and brave threats of germs like malaria.
It was in 1818 that Colonel Everest joined the expedition as second in command. There are records where Lambton has observed that “the entire native establishment was struck down with malignant fever. Many perished miserably at the roadside.” The story of their journey has been recalled both in the ‘Account of the Operations of the Great Trigonometrical Survey of India’ by the Survey of India, and in newspaper accounts. An article from The Argus newspaper in Melbourne in September 1873 cites journal records of Everest, who wrote the following when the survey extended to the Godavari-Krishna basin. “The climate,” wrote Everest, “Was very deadly. It is easy to conceive what a waste of life and health was caused by this exposure to the pitiless pelting of the tropical rains, in forest tracts teeming with miasma…” In addition to succumbing to such fevers and the ferocity of wild animals, in several places, tribals were up in arms against the company.
They also had difficulties getting permission from the local authorities and many a time Lambton was asked to do only one part of the survey and skip the verification that was done with a 65-foot chain. By some accounts, over the course of the entire survey lasting about 70-odd years, the number who died could outnumber the 18th century wars’ tolls in India.
Finding an elevated point to carry out measurements was another difficulty. Hillocks were a good option to mount the instruments, and in many parts of south India, temple gopurams were used. In the North, 60-foot towers were constructed. Platforms would have had to be built for the theodolite, and scaffolding constructed, says D H Rao, veteran civil engineer and Madras history enthusiast.
A typical company consisted of four elephants for the ‘tiger-wary’ principals, 30 horses for military officers and 42 camels for supplies and equipment. However, “Camels were not present in the South. They used pack bulls,” points out Muthiah. The 700 or so labourers traveled on foot.
Whenever the group entered a district where triangulation had not been done, the company would be asked to make a preliminary survey and also furnish sketches of any forts in the region, for military purposes. At one point, he was even asked to stop, as fear has arisen among the British officers about multiplying copies of the maps, and he was required to return all the maps. But this was soon overruled and he was back on his feet.
“He was still in the prime of life and and the full vigour of an unusually robust and energetic manhood, he was hardly known to have had a day’s illness,” say records, and so he remained, dedicated until he met his end at Maharashtra, where his body lies.
“Today, we do what is called rapid survey, and to do a 25 feet by 25 feet, it would take four people one month. You do the math,” says a Survey of India official. Records say that Lambton was even prepared to recognise influence of not only irregularities in earths surface but also varying densities beneath the surface.
Even 213 years later, the relevance is still intact – the great arc that cut across the lands still makes its mark – An indelible mark that mapped the area of 1.47 lakh square kilometres.