The men who measured Earth’s curves
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For much of 1966, John Keay wrote pamphlets and newsletters to persuade Londoners to hire the One Number Service’s plumbing, gardening and household services.
From his table stacked with mass mails in London’s West End, Keay, the marketing director at One Number Service, began a journey halfway across the world and unearthed and narrated historical stories from all over Asia. He discovered that the world’s highest peak was named after a man who had neither seen the peak nor had any interest in mountains.
Keay’s unlikely journey began when a friend suggested that he might want to visit Kashmir in India for his summer vacation in 1966. Keay took the bait, and soon jumped on a plane to Srinagar. He rented a houseboat on the Nagin Lake, leaving it only to go hiking in the mountains and fishing in the streams nearby.
After two weeks, he flew back to London. But Kashmir’s mountains and streams refused to relinquish their hold on his thoughts.
Keay had grown up with a great love of reading and writing. “But I wasn’t presumptuous enough to think I could make money through writing books for a living,” he said. But now he wondered—did he really want to sell gardening and mopping services all his life? “All I wanted to do was to go some place and stay there long enough to find out if I could write and if I could get stuff published,” he said.
In July 1968, two years after his first glimpse of Kashmir, Keay finally pulled the trigger. He handed in his resignation, and flew into Srinagar again.
Keay then edited and revised the guidebook A Handbook For Travellers in India, Pakistan, Nepal, Bangladesh And Sri Lanka. In 1973, he wrote his first book Into India, an introductory book for Western travellers. After all, someone writing for The Economist couldn’t be bad, publishers told themselves. Over the next couple of decades, he would write more than 20 books on the history of India, West Asia and South-East Asia, and become an authority on the region.
Keay’s first big leap into writing was inspired by what he saw all around him in Kashmir—the Himalayas. He wondered how these cold, hostile mountains had been first explored. He asked around, pored over books and manuscripts, and wrote the story of the early explorers of the Himalayas in his 1977 book When Men And Mountains Meet.
Yet, over the years, he realized that his research only illuminated a part of the story. Sure, these pioneers had explored these mountains, but they hadn’t measured these mountains’ heights. That had happened much later—but how had this measurement been done?
Surely you could not drag a measuring tape up thousands of metres while you dodged rocks raining down beside you. If you were gasping for scarce oxygen, or were clutching your mittens to keep your fingers from being lopped off by frostbite, ascertaining your altitude would be the last thing on your mind. So how did these men from an era before GPSes and barometers measure the heights of mountains?
When Keay sought answers, he found a story of a scientific undertaking of Herculean proportions. The epic tale he discovered began 2,000 miles away from the Himalayas—and had nothing to do with the Himalayas or their altitudes.
In 1802, after the British had conquered Mysore by defeating Tipu Sultan, William Lambton, a lieutenant colonel under Arthur Wellesley, began a survey to map the entire British territory from Madras to Mangalore.
His methodology was straightforward. He picked the distance between a flagpole on the beach at Madras and the grandstand at the Madras racecourse as his “baseline”—he measured its 5.85km length with a 100ft-long chain.
He then picked a hill tens of miles away, and measured its angle of elevation and horizontal angle from both the beach and the grandstand. From the length of the baseline and the horizontal angles, he calculated the distance of the hill from the beach and race course using trigonometric formulae. From this horizontal distance and the vertical angles of the hill’s top, he would calculate the hill’s height using trigonometric formulae (or what he called triangulation).
And so Lambton would continue, walking from hill to hill with his team, fixing the position of each hill along his way, until he had mapped with pinpoint certainty places and distances along the 660km distance from Madras to Mangalore.
It took three years to complete this East-West mapping, yet this was only the beginning. Lambton and his team now marched south from Bangalore, to plot locations and elevations of places along a north-south line. Lambton wanted to map the north-south span of British India, starting from India’s southern tip Kanyakumari.
Lambton’s ambitions had grown way grander than mere mapping of British territory in India. He wanted to “determine by actual measurement the magnitude and figure of the earth”. He wanted to find out if Earth differed from a spherical shape, and if so by how much, and thus answer a fundamental scientific question.
To do this, he would measure locations of stars in the night sky from different places whose locations he was also measuring by triangulation—and calculate the latitudes of these locations. With these latitudes, Lambton would calculate the length of a degree of latitude in miles.
By comparing this length of a degree at various locations on India’s north-south “arc”, Lambton would calculate how much Earth deviated from a perfectly spherical shape. He called his project the Great Indian Arc of the Meridian, and his team was called the Great Trigonometrical Survey of India.
The adjective “great” may have appeared immodest, but given the unprecedented ambitions of Lambton’s quest, it hardly seems inappropriate in hindsight.
His team grew over time to more than 150 escorts, signalmen, porters, mahouts and runners who lugged instruments, pitched tents, cooked food, and planted flags atop hills whose positions they observed from theodolites placed on other hills or points. They hacked their way through impenetrable jungles and thick undergrowth, sometimes taking weeks to cross tens of miles.
They built boats to cross rivers in spate. They braved wild animals, insects, rain and strange diseases, to which they gave names like “Malabar ague” and Yellapuram fever. Often they left behind team members afflicted by fevers, injuries and death. Lambton and his intrepid band roughed it out for years, leaving behind cities, towns and comfortable beds and food for the wild outdoors of a country they had no idea about, to chase a dream of solving a problem in abstract science that few people understood or cared for.
Sometimes, there would be no hills nearby—and Lambton’s team would improvise by lugging the theodolite up gopurams of temples to take measurements. Once, while hauling the theodolite up the Brihadeshwara temple in Tanjore, the massive instrument slipped and crashed down. Its finely calibrated surfaces were smashed to a crumpled mess. The Great Trigonometrical Survey of India seemed to have fallen off the tightrope it was perched on. Lambton’s head slumped, but only momentarily. He sat inside his tent for weeks, repaired the entire instrument by himself, and resumed the journey with the repaired theodolite.
Once readings were taken, Lambton had to perform incredibly complex calculations to ascertain positions, distances, heights and latitudes, all with pen and paper, without computing devices. He would take more than 200 astronomical observations in addition to trigonometric observations to calculate the latitude of each place. It was estimated that the entire project involved 9,230 unknowns and “unwieldy equations exceeding anything of the kind ever attempted”. Producing a fair copy of a report often took Lambton as long as five months.
By 1818, Lambton and his men had crawled from Kanyakumari to Hyderabad, measuring, recording, calculating—and chasing an incredible dream over 13 years (16 if you include the three-year-long march from Madras to Mangalore). They had traversed 700 miles (around 1,020 km), or 10 degrees of latitude, by foot, the “longest that has ever been measured on the surface of the globe”, easily surpassing other such surveys in France and England.
Lambton had not only mapped south India, but had also done it with inch-perfect accuracy. When he physically measured a 6-mile- long baseline in Bangalore, the difference between the triangulated distance and the actual distance was a mere 7.6 inches—an error rate of 0.002%. He had discovered that Earth was not spherical or egg-shaped, but grapefruit-like—and he had calculated the compression of Earth’s spheroid to be 1/310 from the 10 degrees of latitude he had measured.
Aided by Everest and his growing team’s support, Lambton continued to soldier on up the length of India, hoping to advance to Nagpur and eventually Agra. Lambton, although estimated to be just under 70, was in the pink of health, and had hardly ever fallen sick in India.
In 1822, in Hinganghat near Nagpur, Lambton, who had just recovered from a rare bout of tubercular cough, celebrated with a drink of madeira. He went to sleep, and never awoke again. He left behind a team that wondered if anyone could ever fill the big shoes he’d abruptly left behind. The responsibility of taking the Great Trigonometrical Survey of India to its conclusion in Agra descended unexpectedly upon Lambton’s new deputy George Everest.
While Lambton was loved and revered by his team, Everest was feared. Unlike Lambton, he would insult native Indians and people he called “half-bred”. He’d get into vicious rows with other officers for petty reasons. Unlike Lambton, who never left India, Everest spent the time from 1820-22, and 1825-30, away from India to convalesce from illnesses he had suffered here. Yet he was politically savvy enough to get himself appointed the surveyor general of India in 1829, in addition to his role of superintendent of the Great Trigonometrical Survey of India.
Still, Everest was a man as driven as Lambton when it came to the Great Arc. In his absence, he had had his subordinates take the project eastward from Sironj in Madhya Pradesh to Calcutta. In 1833, Everest returned to lead the survey south from Dehradun to Sironj to complete the north-south arc, with his support staff of “two assistants, three sub-assistants, four elephants, forty-two camels, thirty horses and 700 natives”.
Finally, in 1837, the entire north-south arc had been concluded, completing Lambton and Everest’s dream. But the world had changed in the decades since the start of the Great Trigonometrical Survey. The British used maps to delineate their areas, much like dogs marking their territories. In a political climate where map-making had become an instrument of public policy, Lambton’s ambition—and achievement of measuring Earth’s shape—had become insignificant, and was forgotten.
In 1843, with the survey’s calculations finished, Everest headed home to England for good. The main north-south arc had spawned other such projects by now. Andrew Waugh, who succeeded Everest as surveyor general of India, started work on what he called the North-East longitudinal series, to survey and map the area from Dehradun to Assam.
This project progressed along the foothills of the Himalayas. With Himalayan mountains so close by, surveyors often trained their theodolites toward them and measured their elevations and heights. Waugh had measured Nanda Devi, and then Kanchenjunga, and found that they were far taller than peaks in the Andes that had been considered the highest peaks in the world. In November 1847, yet another peak in the distance near the India-Nepal border appeared taller than either Kanchenjunga or Nanda Devi.
Waugh called it “gamma”, and while it was clear that it was the highest peak in the world, he spent the next four years refining his calculations and observations—fussing about refraction coefficients and the datum zero height from the sea level at Karachi, for the fact of discovering the tallest peak in the world wasn’t something Waugh considered as important as the immediate triangulation work he was busy with. The commonly known story of Waugh’s assistant Radhanath Sickdhar running into Waugh’s room to exclaim that he had discovered the tallest peak in the world, is apocryphal. That incident never happened.
Finally, in March 1856, nine years after the peak was first observed, Waugh wrote letter No. 29B to his deputy surveyor general in Calcutta, announcing that he had discovered the highest peak in the world and that he would name it “in testimony of my affectionate respect for a revered chief”—his predecessor George Everest.
Thus it was that the only trace of the Great Trigonometrical Survey of India’s 40-year-long march across the plains of India was the name of a peak far away from where most of its work was done.
Keay travelled the length of India, and saw for himself the sweaty plains, the ghats, jungles and valleys that Lambton and Everest had braved. He patched together the story of the Great Trigonometrical Survey’s odyssey—and produced his book The Great Arc in 2000. “It was the quest which I loved,” he said. “And besides, it was an excuse to travel.”
One of his journeys took him to Hinganghat, a town full of cotton mills and godowns with corrugated roofs. His driver summed up the place, “Hinganghat like shit.”
Keay was on the quest for William Lambton’s grave. After being told that nobody knew of a British man from 150 years ago buried in the town, he went to a Muslim graveyard. There, Keay found an oblong plinth without a headstone. The letters scrawled on the once-wet mortar were hardly legible, but there was no mistaking four of the leters “L, A, M, B” and three numbers of the year of birth “1,7,5”, even if the rest had been dissolved by time.
This was all that remained of William Lambton, the man who had led perhaps one of the most intrepid geographical expeditions of all time, an expedition whose only trace today is a peak it had little interest in.
“He deserved better,” said Keay.
John Keay’s next book Midnight’s Descendants: South Asia From
Partition to the Present Day will be out in January.
Shamanth Rao (ShamanthRao.com) is a writer based in San Francisco, California. He edits the travel section of Mint Lounge.