The Great Arc

by John Keay

  This sounded most promising. It looked as if Crawford had made the first serious attempt at measuring the Himalayas. Sadly expectations, raised to the snowline in one paragraph, were promptly dashed to the plains in the next.

  But the drawings and journal of this survey have been unfortunately lost.

  The loss might have been recouped by another writer who happened to have cited Crawford’s original findings, but he had done so only in a tantalising telegraphese: ‘Double altitudes observed by sextant – allowances for refraction – bearing – computed distance – height by trigonometry – additional height for curvature of the earth – Result, 11,000–20,000 feet above stations of observation.’

  The method of operation remained unclear. How, for instance, had the distance of the peaks from Crawford’s points of observation been ‘computed’? Clearly not in the manner of Lambton constructing his triangle between the beach and the grandstand; but if by horizontal triangulation, this required a base of precisely known length between two points of observation at least twenty miles apart. Crawford’s base was rumoured to have been less than a quarter of a mile, and of doubtful accuracy.

  Moreover, ‘heights above stations of observation’ were useless without knowing how high such stations of observation were above sea-level. This information was not given, and an inferred height of about 4,500 feet was mere conjecture. Sea-level deep in the mountains would remain conjectural for the next fifty years, another of the many imponderables which dogged Himalayan observations.

  Nevertheless the report put paid to one common misconception. The Himalayas were not a line of active volcanoes. The plumes of smoke which appeared to stream from their summits were simply windblown snow. Additionally, Crawford’s attempted measurements represented an important advance on the guesswork which had preceded them. During the next two decades, while Lambton laboured at the triangles of his Great Arc far away in the tropical south, Crawford’s Himalayan claims would trigger a wave of both curiosity and controversy in respect of the snowy mountains which, swagged below the Tibetan plateau, defiantly described a great arc of their own along India’s northern frontier.

  The existence of the Himalayas had been known to the ancients. Ptolemy, the first-century astronomer and geographer, had called them the ‘Imaus’ and ‘Emodi’, both words presumably derived from the Sanskrit (H)ima-alaya, or ‘Abode of Snow’. He showed them as a continuation of the Caucasus mountains running east from the Caspian Sea. Subsequent travellers, like Marco Polo in the thirteenth century, usually trod some version of the ancient Silk Route which, though skirting the north of the western Himalayas, left Tibet and the central Himalayas well to the south. But Tibet had been regularly penetrated in the seventeenth century by Jesuit missionaries from India, and the first convincing account of the mountains comes from one of their eighteenth-century successors. This was the Italian Ippolito Desideri who in 1715 departed Kashmir for Lhasa and was horrified to find, even in late May, the snow deep on the trail and the mountains ‘the very picture of desolation, horror and death itself’. ‘They are piled one on top of another,’ he wrote, ‘and so close as scarcely to leave room for the torrents which course from their heights and crash with such deafening noise against the rocks as to appal the stoutest traveller.’

  Fifty years later the eruption of British arms into Bengal which presaged the beginnings of the Raj brought more sober appraisals. In the 1760s Lord Clive had commissioned Major James Rennel to survey the territories which, as Colonel Robert Clive, he had so unexpectedly seized. Rennel, the father of the Bengal Survey and its first Surveyor-General, travelled north to the frontier with Bhutan and thence noted several peaks which were snow-covered throughout the year. One in particular stood out; it may have been Chomo Lhari. Although he made no attempt to measure it and considered the hills as outside his field of operations, Rennel did alert the world to the possibility that the Himalayas were ‘among the highest mountains of the old hemisphere’.

  Curiously, their main rival as Eurasia’s highest summit was thought to be not Turkey’s Mount Ararat (16,946 feet) nor France’s Mont Blanc (15,781 feet), but ‘the peak of Tenerife’ (12,195 feet). While other quite prominent heights remained uncertain, mainly because they lay so far from the sea and could not therefore be assessed against sea-level, that on the island in the Canaries conveniently rose straight from the Atlantic and lay on a busy sea-route round Africa. Mariners usually possessed sextants, and so the Tenerife peak had been much observed. But at the then accepted height of 15,000 feet, it was still overvalued by almost a quarter. Such was the difficulty of measuring even convenient altitudes.

  Rennel had made comparison only with ‘the highest mountains of the old hemisphere’. The new hemisphere, or New World, was a different matter altogether. Already the Andes in particular were known to be exceptionally high. Courtesy of that French expedition to measure a degree of latitude on the equator, the peak of Chimborazo in Ecuador had been correctly measured to within a few feet of its 20,700 above sea-level, and so was reckoned the world’s highest. That Bhutan’s Chomo Lhari was in fact over three thousand feet higher than Ecuador’s Chimborazo would have surprised Rennel.

  One of Rennel’s most distinguished contemporaries was less reticent and actually knew the name Chomo Lhari, or ‘Chumalary’. Sir William Jones, a judge in the Calcutta High Court, was unquestionably the greatest scholar England ever sent to India. Dr Johnson had hailed him as ‘the most enlightened of men’, Edward Gibbon as ‘a genius’. Linguist, poet, historian, philologist and naturalist, Jones founded the Asiatic Society of Bengal, whose publications would include Lambton’s occasional reports, and he led the field in almost every branch of Oriental studies. It was thanks to Jones that the height of the Himalayas had been added to the agenda of Orientalist research.

  ‘Just after sun-set on the 5th of October 1784,’ writes Jones, ‘I had a distinct view from Bhagilpoor [Bhagalpur on the Ganges in Bihar] of Chumalary peak … From the most accurate calculations that I could make, the horizontal distance at which it was distinctly visible must be at least 244 British miles.’ This extraordinary sighting argued strongly for an immense elevation; but Jones also had the advantage of having corresponded with two men who had actually crossed the mountains. They had been sent on separate trade missions to Tibet and had followed an existing and not especially challenging route through Bhutan. But from their reports of latitudes observed and distances gauged, Jones correctly surmised that the mountain wall was many miles thick as well as high. The highest peaks lay well back from the immediate horizon ‘on the second or third ridge’. And despite Rennel’s caution, after careful study of these and other reports Jones was prepared to chance his arm. He was in fact the first to declare that there was now ‘abundant reason to think that we saw from Bhagilpoor the highest mountains in the world, without excepting the Andes’.

  In this, as in his other pronouncements on Indian history and philology, Jones’s genius lay in divining a truth which as yet defied proof. Such though was his stature that, while some questioned his judgements, more were inspired by them to seek the missing evidence.

  Foremost amongst the latter were two cousins called Colebrooke. Robert Colebrooke was a soldier who in 1794 succeeded to Rennel’s post as Surveyor-General of Bengal, Henry Colebrooke an antiquarian and administrator who would become president of Jones’s Bengal Asiatic Society and whose broad scholarship mirrored, albeit dimly, that of its founder. While Colonel Robert would do most of the travelling and would keep an entertaining journal enlivened with delicate sketches, cousin Henry acted as impresario, presenting the findings of Robert and others to the world and pontificating about them.

  It was Henry Colebrooke who first took an interest in the mountains. Posted as Assistant Collector to Purnia in northern Bihar, he found himself about ninety miles closer to the snowy peaks than Jones had been at Bhagalpur. During the early 1790s he began a series of observations to try to establish their heights. Assuming their distance to
be about 150 miles, and finding their mean elevation to be I degree and I minute (1°1') above the horizontal (degrees, like hours, are divided into sixty minutes, each of sixty seconds), Henry Colebrooke deduced a height of 26,000 feet.

  The question of what this meant in terms of sea-level was not too critical; Purnia lay in the lower Gangetic plain, which was known to be only one to two hundred feet above the tidal reach of the Bay of Bengal. But while heights deduced from observations taken on the plains might be safer in respect of sea-level, they suffered from being much too distant from the snowy peaks and far too vague as to the exact extent of this distance. Baldly stated, the observer either had a good idea of his own elevation and a poor one of the peaks’, like Henry Colebrooke from the plains, or no idea of his own elevation but a relatively good one of the peaks’, like Crawford in Nepal.

  It seemed a no-win situation, but when Henry Colebrooke was posted away from Purnia, he strongly recommended the matter to the attention of cousin Robert. Robert’s opportunity would have to wait twelve years. Meanwhile Crawford and others brought back their exciting but scientifically questionable reports of the Nepal Himalayas.

  At the time the Kingdom of Nepal afforded the only access to the highest peaks. Much bigger than today, its territory then extended east to Bhutan and west to the Panjab, thus embracing almost the whole sweep of the mountains. If their secrets were to be explored, it had to be through Nepal. Briefly at the turn of the century this looked feasible as the Court at Kathmandu welcomed a couple of British missions, including that to which Crawford was attached. But in 1804 the Anglo – Nepalese treaty of friendship was cancelled and the border closed. The kingdom retreated back into an isolation which, to the chagrin of generations of surveyors and then climbers, would prevent all but diplomatic access for the next 150 years. If the British were ever to get within easy surveying distance of what Jones had so boldly dubbed ‘the world’s highest mountains’, it would have to be by removing some of these mountains from Nepali sovereignty.

  Given the pace of British expansion under Governor-General Richard Wellesley’s direction, this did not seem too remote a possibility. No sooner had southern India been ‘settled’ by wresting Mysore from Tipu Sultan in 1799–1800 than the Governor-General turned his attention to the Marathas, a confederacy of rulers who exercised a loose sovereignty over much of the rest of India. There were three Anglo – Maratha wars, and the most sanguinary and significant of them was the second, waged by Wellesley in 1803–4; indeed, it was to ‘lay the foundations of our empire in Asia’, as he put it. It also laid the foundations of brother Arthur’s reputation as an inspirational commander when he won important battles in west and central India including that at Assaye, which he would always recall as a finer victory than Waterloo. As a result of these conquests, Bombay was at last rewarded with territorial gains in western India equivalent to those won forty years earlier by Calcutta in Bengal and four years earlier by Madras in Mysore.

  Since Maratha power at the time reached north to Delhi and the Ganges, the opportunity was also taken to extend the territories of British Bengal upriver from Bihar. Called the ‘Ceded [in 1801] and Conquered [in 1803] Provinces of the North West’, a large tranche of what later became the United Provinces and is today Uttar Pradesh was added to British India. It included Agra and Delhi itself, plus the banks of the Ganges and Jumna right up to where these rivers debouched from the mountains in what was then still western Nepal.

  In these newly acquired districts lay Robert Colebrooke’s chance to take up the challenge suggested by his cousin Henry. As Surveyor-General for Bengal it was imperative that he map the new territories; and in doing so, he hoped for the first time to push up to the Himalayan foothills in the west and perhaps penetrate them to locate the sources of the Ganges and Jumna rivers.

  His resultant survey of 1807–8 had no pretensions to the accuracy of Mackenzie’s in Mysore, let alone to the ‘correct mathematical principles’ in which Lambton took such pride. Colebrooke travelled as much as possible by river-boat. Distances were measured along the bank with a wheeled apparatus known as a perambulator, and bearings were taken to plot locations and occasionally establish latitude, but not with a view to triangulating the territory. It was, in fact, what was called a ‘route survey’, and its purpose was largely strategic and military. Roads and rivers by which troops could be moved were of the essence; so were fortified towns and other obstructions. The hills were of interest less for their heights than their hollows through which an enemy might invade or, more realistically, a British force advance.

  But Robert Colebrooke was well aware of Lambton’s work and, while complaining that nothing had been heard of the elusive Yorkshireman for a long time, chanced to mention that it was ‘a pity that a survey conducted on such scientific principles is not extended all over India’. Others would soon be thinking along the same lines. Lambton was setting new standards of accuracy which rendered all prior surveys approximate if not redundant. There was no point in wasting weeks plotting triangles with pocket-size theodolites if the Great Trigonometrical Survey with its half-ton instruments and its page-long equations might one day appear over the horizon.

  A family man and a happy one, Robert Colebrooke took along on his survey his wife Charlotte, or ‘my young lady’ as he always calls her, plus the two eldest of the nine children which she had borne him in as many years of marriage. Travelling light was not, therefore, an option. According to Colebrooke’s diary, when they forsook their boats his ‘equipage consisted of 4 elephants which carried two marquees and 6 private tents; five camels for my baggage; a palanqueen, a mahana and a dooly [different kinds of litters] (the latter two carrying my two children and their nurse), 12 bhangies [bearers for carrying the litters], 12 coolies [all-purpose porters], 12 lascars for pitching the tents, and an escort of 50 sepoys [Indian soldiers]’. Not surprisingly the Colebrookes stuck mainly to their boats.

  Throughout his diary Colebrooke happily mixes domestic details with professional notes and extempore sketches. Tigers kept them awake at night, the boats got repeatedly stuck on mud banks, and whole districts turned out to stare at them. Clearly the people had not previously come across a European – let alone a breeding pair complete with offspring. Colebrooke bore it all with grace and humour. Out with his gun of a dewy morning, nostrils flared to enjoy the post-monsoon freshness, the forty-four-year-old Colonel was loving every minute of it. This was the life. It was snipe for breakfast, it was tea with the Nawab, it was India in all its pre-colonial innocence. There was no better place, no better job.

  During 1807 the Colebrookes pushed up the Gogra and the Rapti, tributaries of the Ganges, and came within sight of the mountains. At Gorakhpur Robert took his first series of observations of the snowy peaks. Christmas was spent with the small European community in the city of Lucknow. Then, leaving his family behind for what would be a long overland slog, in early 1808 he pressed on to the north-west.

  Working along the foot of the mountains, he now encountered thick swamp-forest and the most tiger-infested jungles in India. This was the infamous terai, a low-lying belt of tall grasses and towering trees which skirted Nepali territory and was a more effective frontier than the hills themselves. It would claim the lives of a legion of surveyors. Colebrooke himself went down with fever. He took another series of observations to the snow-capped peaks from a place called Pilibhit (near Bareilly at the south-west corner of today’s Nepal frontier), but gave up the idea of pursuing the Ganges and the Jumna to their sources. Instead he deputed his assistant, Lieutenant William Webb, to make the attempt.

  By April Colebrooke was too weak for anything but river travel. The fever was diagnosed as malaria, complicated by dysentery. He continued to write his journal but the sketches became fewer and the entries shorter. Drifting downriver to Cawnpore (Kanpur) in mid-August he was ‘much worse’; and the heat was greater than anything he could remember. Debilitated and delirious, he became obsessed by the monsoon thunder-clouds which p
iled ever higher and heavier above the river. White-flecked, they towered above him with Himalayan menace. On 12 September he wrote again of an approaching storm. The lightning and thunder continued throughout the night.

  13th. The weather was so bad as to oblige us to lay

  all day at Jungeera. Rainy and stormy night.

  14th.—

  With a date and a dash the diary ends. Robert Colebrooke died in the early hours of the morning of the twenty-first, ‘a victim to his exertions in the cause of science’ as one of his colleagues kindly put it. He was forty-five, not a great age but about the average for Europeans in India at the turn of the century. Life, however delicious, was short. By chance he breathed his last at Bhagalpur, the place whence Sir William Jones had first hailed ‘the highest mountains in the world’.

  Cousin Henry now owed it to Robert’s memory, to the nine fatherless children and the thirty-three-year-old widow, as well as to his own convictions, to present an overwhelming case for the Himalayas. Marshalling the testimony of those earlier travellers into Tibet, of Crawford in Nepal, of Jones, and particularly of cousin Robert and his assistant Webb, he laboured intermittently over his great paper On the Height of the Himalaya Mountains for the next seven years.

  Like Henry, it appeared from his diaries that Robert too had become convinced that the peaks he had observed from Gorakhpur and Pilibhit were ‘without doubt equal, if not superior, in elevation to the Cordilleras of South America [i.e. the Andes]’. At Gorakhpur, Robert had reported that, while a small crowd ‘watched me and my instrument in silent astonishment’, he had taken angles to two peaks and had deduced for each ‘more than five miles in perpendicular height above the level of the plain on which I stood, which must be considerably elevated above the level of the sea’. Five miles was 26,400 feet. He could not be more precise because of uncertainty about the allowance to be made for refraction, that bending of sight-lines by the earth’s atmosphere which had so exercised Lambton in Madras. He had used the standard tables showing the deductions to be made, but he had little confidence in them.