The Great Arc (8 page)

It is known, though, that his men were not immune and that his second assistant was indeed overtaken by the ‘Malabar ague’. Nearly dead (from the cure if not the ague), he was invalided home. But India’s loss became England’s gain; for Henry Kater would go on to become one of the most distinguished physicists of his age, a leading light of the Royal Society, and the inventor of ‘Kater’s pendulum’ and the prismatic compass. In 1823 he would send his old boss news of a miniaturised theodolite which he had just designed; it was as accurate as their ‘Great Theodolite’ but could fit in a box no bigger than a suitcase and be carried by one man. Sadly Lambton was himself in a box beneath the turf of Hinganghat by the time the letter arrived.

Instead of filling his reports with human detail, Lambton stuck to science. His two stations atop the Western Ghats gave heights above the level of the sea as measured back at Madras of 5,583 and 5,682 feet. From that fifteen-foot slope to the grandstand at the Madras racecourse he had carried his elevations across a subcontinent and up into the clouds. That these were indeed the first precisely measured peaks in India became clear when he continued his triangles down to the coast. Sea-level at Mangalore on the Malabar coast of the Arabian Sea
as deduced from that of the Bay of Bengal on the opposite side of the peninsula was found to differ from its actual level by only eight feet. Given the variable and still uncertain properties of refraction, and given the tidal variations, this was as satisfactory a proof of the accuracy of Lambton’s vertical angles as the 3.7-inch differential in the Bangalore base had been of his horizontal angles. It was such irrefutable logic which the scientific establishment in Europe would find so painfully wanting in Henry Colebrooke’s claims for the height of the Himalayas.

A more surprising discovery was the revelation that the Indian peninsula had shrunk. Against then current maps which, largely based on coastal surveys and astronomical reference, supposed a width of around four hundred miles, Lambton’s survey conclusively proved that it was only 360 miles from Madras to Mangalore. A coastal strip of some ten thousand square miles was thus consigned to the Arabian Sea. Thanks to Lambton, British India sustained its greatest ever territorial loss. Fortunately this result mirrored almost exactly that obtained in France when in the seventeenth century a survey had found that Brittany had been represented as protruding over sixty kilometres further into the Atlantic than it actually did. At the time Louis XIV had complained about his surveyors having ‘cost me a large part of my territory’. But the precedent thus set exonerated Lambton from similar censure, indeed served to confirm the value of his work.

No base-line was measured on the Malabar coast. The onset of the monsoon in 1805 forced Lambton back to Bangalore and, although he returned to the west coast in 1806, circumstances again prevented the assembly of men, chains, tripods and coffers, let alone the extensive ground clearance, that was essential for base measurement. He regretted the failure but, having completed the first longitudinal arc across the peninsula, he now concentrated on his latitudinal measurement, or great arc of the meridian. (Confusingly, measurements which
follow a line of latitude are known as ‘longitudinal’ because it is degrees of longitude which they traverse and measure – and vice versa.) With the Bangalore base as its starting point, the triangles of what Lambton later called the ‘Great Indian Arc’ were extended north about a hundred miles to where British territory ran up against that of the independent Nizam of Hyderabad, and then south towards Cape Comorin (Kanya Kumari) at the tip of the subcontinent. The next base-line was in fact measured on the Great Arc near Coimbatore, about 140 miles south of Bangalore, in 1806. In its length of over six miles the difference between the triangulated measurement carried from Bangalore and the actual measurement on the ground came to 7.6 inches.

Another long stride of similar distance would carry the arc down to Cape Comorin in 1809; and another base-line measured near Tirunelveli (south of the ancient capital of Madurai) would produce an equally satisfactory result. But any celebrations over the successful completion of the southward arc were marred by anxiety. For in the meantime, with a particularly sickening crash, disaster had struck. What even the phlegmatic Lambton would concede to have been a catastrophic accident had thrown the whole enterprise into jeopardy.

The trouble had begun amongst the sea of waving palm fronds which blanketed the flat delta region of the Kaveri river east of Tanjore (Thanjavur) in southern Tamil Nadu. In late 1807 Lambton had left the Great Arc to conduct a parallel triangulation down the east coast from Madras. This meant in effect continuing that short arc measured in 1802 to establish the length of a degree as a preliminary to his whole survey. The government was now urging the need for a web of triangles covering the whole peninsula as the basis for a map rather than just the chains of triangles, running north – south and east – west, which promised most to the geodesist. Extending a series down each coastline and then filling in the
triangles between these and his Great Arc looked to be the best way of meeting this demand. Hence Lambton’s progress south from Madras in 1807–8.

All went well until he ran out of hills and
droogs
in the wide and tree-choked Kaveri delta. Visibility through the coconut palms was impossible without a major felling programme, and the construction of towers was as yet considered an unthinkable expense. Tamil Nadu is, though, famous for its temples. The Tamil temples are in fact the largest in India, and although their numerous shrines and halls may not be especially lofty, they are usually contained within high walls whose gateways, or
gopurams
, support magnificent stacks of sculpture which soar above all else, palm trees included. The solution to Lambton’s problem was spectacularly obvious.

There were good precedents for using ecclesiastical buildings. In France surveyors had scaled the towers of several cathedrals including Notre Dame in Paris and, en route to a junction with William Roy’s triangles across the English Channel, that of Rouen in Normandy. Roy himself had measured angles from a platform erected around the ball and cross on top of the dome of St Paul’s Cathedral in London; and to obtain a flat working area on the spire of Norwich cathedral, he had actually removed its topmost courses of stonework. No such liberties could be taken with temple structures in India. The temples’ brahmins had to be carefully and generously handled. Yet the riot of sculpture made climbing easy, and from atop a
gopuram
the level terrain beneath the sea of coconut fronds meant excellent visibility.

Hopping from
gopuram
to
gopuram
, the survey continued south, but in 1808 even the temples ran out. From that of Kumbakonam Lambton had sighted to the west the tower of Tanjore’s Rajarajeshwara temple. He now decided to abandon southward progress and to carry his triangles inland to link up with the Great Arc by way of Tanjore.

The Tanjore Rajarajeshwara, or Brihadishwara, is dedicated
to Lord Shiva and was built in the early eleventh century by the great king Rajaraja I, the founder of a south Indian empire whose power reached from Sri Lanka to Malaya and Bengal. Unlike later temples, its
gopurams
are modest, but the main shrine itself is graced with a pyramidal colossus of stonework, 217 feet high. It is in fact the loftiest and, to many minds, the loveliest temple tower in all India. Here was a unique eminence in every way worthy of Lambton’s unique instrument. With ropes and pulleys the lascars were soon hauling the Great Theodolite to its summit.

The topmost capstone of a south Indian temple tower is sometimes called an
amlaka
, because of its round and often ribbed resemblance to a myrobolan fruit. That of the Rajarajeshwara is more dome-shaped and is carved from a single block of granite, over a hundred feet in circumference and estimated to weigh eighty tons. It is thought to have been originally manoeuvred into its exalted position by way of an earthen ramp specially constructed for the purpose and all of four miles long. Compared to this feat, the hoisting of a mere ten hundredweight of machinery looked simple. The pulleys were attached to the
amlaka
; the vast paved courtyard in which the temple stands left ample room for the rope-pullers to manoeuvre; and to keep the theodolite clear of the statuary a guy rope was attached and then probably lashed round one of the pillars of the courtyard’s cloister, as to a bollard.

It was this guy rope which either slipped or, according to George Everest’s later account, actually snapped. The theodolite, disregarding such niceties as plumb-line deflection, swung smartly towards the vertical and there met the sloping sides of the pyramidal tower, knobbly with sculpture, in a splintering crash. Luckily the instrument was still in its box, or it would have been flattened. As it was, the box took the brunt of the impact and was shattered by the statuary as the protruding tangent screw of the instrument’s three-foot circle punctured the packing. The screw sheared and the great circle or dial,
so perfectly cast, so minutely calibrated, and so lovingly handled, was left as bent as a bicycle wheel after a head-on collision.

Lambton seems to have accepted full responsibility. ‘The high mind of the late Superintendent [i.e. Lambton] could not brook the idea of being reproached for this accident,’ recalled Everest, and ‘the circumstances of the case were never, I believe, officially brought to the notice of Government.’ Although the instrument was valued at £650 (to which sum two zeros may be added for a modern approximation), Lambton ordered a replacement from England at his own expense and then retired along with the mangled original to the military workshops at nearby Trichy.

Any person but my predecessor [writes Everest] would have given the matter up as absolutely desperate; but Colonel [Captain at the time] Lambton was not a man to be overawed by trifles, or to yield up his point in hopeless despondency without a struggle. He proceeded to Trichy … [and] here he shut himself up in a tent, into which no person was allowed to penetrate save the head artificers.

It was the height of the Indian summer, the same summer which, in the far north, found a delirious Robert Colebrooke dreaming of cool Himalayan peaks as he watched the monsoon clouds build above the Ganges while the sacred river bore him downstream to his death. Lambton, like Achilles, never budged from his tent. But far from sulking, he fussed over his beloved instrument through the dog days and sweat-soaked nights like a doctor fighting for the life of his patient. Outside his men waited, their Survey stalled if not permanently halted and their employment in doubt. Everest continues:

He took the instrument entirely to pieces, and, having cut out on a large flat plank, a circle of the exact size
that he wanted, he gradually, by means of wedges and screws and pullies, drew the limb out so as to fit into the circumference; and thus in the course of six weeks he had brought it back nearly to its original shape. The radii, which had been bent, were restored to the proper shape and length by beating them with small wooden hammers.

Everest was profoundly impressed by this whole saga. Although relying on hearsay, he would tell the story often, and elsewhere says that the repair work took six months, not six weeks. He also suggests that the restored theodolite, though usable, never again inspired quite the same confidence. Lambton appears to have been satisfied with it and was still relying on it when Everest joined him nine years later. But Everest would contend that the main triangulation of the next section of the Great Arc as it edged north into Hyderabad would suffer from the instrument’s failings.

Finding fault with men, as with instruments, came easily to George Everest. It would not be out of character for his criticisms to have been a way of trumpeting the higher standards of his own work without inviting the accusation of having personally disparaged his distinguished predecessor. Lambton, on the other hand, had no time for such games. His only recorded criticisms were reserved for those in authority who attempted to curtail his work. Colleagues and subordinates he invariably supported and they revered him without exception.

Moreover it is unthinkable that he, of all people, would have made do with a instrument which he knew to be other than as perfect as humanly possible. If his later work was found to be to a less exacting standard, the explanation lies in his increasing willingness to delegate the actual triangulation to his assistants, Everest amongst them. This was partly dictated by the need to train a successor and partly so that he himself could concentrate
on the more arcane calculations and observations vital to geodesy.

Now perhaps in his late forties and greatly encouraged by recent appreciations of his work from Sir Nevil Maskelyne, the Astronomer Royal in London, Lambton was no longer the tongue-tied stranger from the backwoods of New Brunswick. He was still a slave to science, still immersed in mathematical abstractions, and still largely indifferent to the social wheelings and professional dealings of his fellow officers. But ten years in India had given him the confidence of a man who had finally discovered his life’s purpose. He now purchased, as was standard practice, the rank of Major and, when not in the field, set up house and home on the coast. He even started a family. But if less aloof, he remained just as elusive. While colleagues would certainly have preferred to live in society amongst the British in Madras, Lambton had chosen to live in sin amongst the French in Pondicherry.

L
ambton’s reports, as well as lacking the personal detail which might redeem their Spartan syntax, are also extremely light on dates. Numbers and calculations relevant to his work abound, but the simple digits of day, month and year are omitted. If Everest was later confused about whether the repairs to the Great Theodolite had taken six weeks or six months, it may be because Lambton himself had never bothered to record their completion.

We do have a note of how long was spent in measuring each of his base-lines; additionally we know on which nights he conducted astronomical observations, the dates in this case being an essential part of the data. But how many days he spent fixing any of his trig stations is anyone’s guess. As with the mystery of his age and birth, Lambton seems to have rejoiced in obscuring the record. Geodetic formulae are known as ‘constants’; to a mind obsessed with pinpointing the permanence of place, time’s insidious trickle may have been anathema. Or perhaps covering his tracks through the years was a deliberate subterfuge, another dimension of a retiring and elusive persona.

In 1809, after the catastrophe in Tanjore, Lambton’s triangulation of the extreme south was overtaken by a smart piece of British aggression against the Raja of Travancore in what is now the state of Kerala. The Survey’s presence proved only a minor provocation in what the British historian Sir Penderel Moon calls ‘the least justifiable of the many questionable transactions
by which British power in India [was] acquired’. During the few weeks which the affair lasted, Lambton, swapping geodesy for gunnery, served as a military engineer. Then, after measuring his base-line at the southernmost extension of the Great Arc, he retired to Pondicherry to work on his calculations and produce the map of peninsular India which would embody them.

Pondicherry then, as now, was an undemanding billet. The tree-lined corniche, the stucco villas, and an air of social and ethnic
fraternité
recalled its golden age in the eighteenth century as the crucible of French ambitions for an eastern empire. Technically it was still the capital of French India. But the British had held it for fifteen years and would continue to do so until after Napoleon’s defeat. With a population of only 25,000 it was already a seedy backwater compared to bustling Madras a hundred miles up the coast. Lambton chose it because its cosmopolitan climate appealed to his assistants, few of whom had been born in Britain, and because it was better suited both to his retiring nature and to his greatly changed domestic circumstances.

When and where he had met the mysterious ‘Kummerboo’ is not known. Her name sounds vaguely Hindu but in Lambton’s will she is described as ‘a Moor’, or Muslim. An officer’s loves were seldom transparent and in this Lambton was no exception. According to John Warren, Lambton ‘appeared to disadvantage in mixed companies, and particularly in the company of women’. On the other hand Everest, not much of a ladies’ man himself (although also capable of surprises), calls Lambton ‘a great admirer of the fair sex’. Presumably it was the trussed and trivia-minded British memsahibs whose company showed him to disadvantage, ‘not one of them,’ according to Richard Wellesley, ‘decently good-looking’. Their shyer local sisters, Kummerboo amongst them, must then have been the fair ones – and the not so fair ones – who drew Lambton’s admiration.

It is not improbable that there had been other such liaisons during his long stopovers in the field, athwart a base-line perhaps, or atop a
droog.
We know only of those mentioned in his estate. Kummerboo was provided for because in July 1809, with Lambton in attendance, she gave birth in Pondicherry to his first child, another ‘William Lambton’. Likewise we know of ‘Frances’ who ten years later in Hyderabad bore him a daughter and another son. Frances is described as ‘a half-caste’, perhaps Anglo-Indian or Franco-Indian. Warren hints that Lambton was debating marriage, presumably to this Frances, at the time of his death, a feasible proposition if we discount the Methuselah of tradition.

All three children were acknowledged by him and were baptised. The younger boy seems to have died in infancy, but William junior, after some elementary schooling, accompanied the Survey when in 1815 its headquarters advanced to Hyderabad and, while still only eleven, was put on the payroll as a ‘3rd Sub-Assistant’. When in 1818 a rather correct Lieutenant Everest was posted to the Survey at its then headquarters in Hyderabad, he might easily have mistaken it for a crèche. As well as young William and the pregnant Frances, Lambton’s menage included Joshua de Penning, his senior sub-assistant; Joshua’s natural son Joe, a teenager who was also about to become a 3rd Sub-Assistant; and Joshua’s wife Marie who, although only twenty-two, was already accompanied by nine of the fourteen little de Pennings she would eventually bear.

Nor was that all. Lambton’s original assistants, Warren and Kater, had since moved on, Kater to distinction in London and Warren to head the Government Observatory in Madras. Four army officers had briefly replaced them and had helped complete the triangulation in the south, but in 1811 they were withdrawn as part of a cost-cutting exercise. That left Lambton with just four lowly sub-assistants, all in their twenties and all of whom regarded his headquarters as their home. They were
also all locally recruited and all, to jaundiced British eyes, socially disadvantaged because they had been born in India of at least one non-British parent.

Lambton preferred such company. Kater had been of German birth and Warren was French, though born in Italy and with Irish connections. Joshua de Penning, the most senior of these young sub-assistants, had originally come from a Madras orphanage and was perhaps Dutch by birth. Of the other three, William Rossenrode and Joseph Olliver would both, like de Penning, have long and distinguished careers in the Great Trigonometrical Survey. Moreover both had already fathered, or would soon, sons who followed in their footsteps.

Lieutenant Everest would consider himself very superior to all these ‘gentlemen’, as he called them (the word was meant to emphasise that they were not, like him, officers). Nor would they for their part easily become resigned to Everest’s notions of authority. Lambton they worshipped, but for Everest they simply worked; and if in time Everest would come to think of them and their numerous dependants as his family, it was a family which he had inherited.

Not only did Lambton recruit and train these young men, he also demonstrated the utmost confidence in them. As the Survey faced about and began extending its triangles north from Mysore into the territories of the Nizam of Hyderabad, Joshua de Penning was increasingly entrusted with the Great Theodolite and even with the primary triangulation of the Great Arc. Lambton meanwhile took the field mainly to measure base-lines and to conduct the vital astronomical observations.

Star-gazing was almost as important and certainly more demanding than triangulation. The latter simply fixed the Survey’s points of observation in relation to one another and to base-lines. But to orientate Lambton’s triangles and to establish the position of his trig points on the earth’s surface in terms of latitude and longitude, as well as to detect the
earth’s variable curvature, it was essential that the survey be anchored by astronomical observations. These were usually made by measuring the angles at which planets and stars passed through the zenith as seen from the more important of his trig stations.

The more such observations from any one trig station the better. At the Tirunelveli base-line in the extreme south Lambton had spent twenty-seven consecutive nights closeted in a tent with his zenith sector (an instrument with a telescope and a giant five-foot ‘sector’ for observing these vertical angles). The result was more than two hundred astronomical observations for latitude at this one location, the mean of which could be taken to give as precise a value as circumstances allowed.

To establish the distance between two points several hundred miles apart, say at the current extremities of the Great Arc, it was important that the same stars be observed at each place, preferably at the same time and with identical instruments. This was asking a lot of the Indian climate since the monsoon in the north of the peninsula does not coincide with that in the south. It also asked a lot of the Survey’s resources and would challenge even Everest’s genius for organisation. Nevertheless, Lambton was able to make some important corrections to existing maps. The position given to the great city of Hyderabad, whence he now directed the progress of the Great Arc through the territories of the Nizam, he found to be ‘out [by] no less than eleven minutes in latitude, and upwards of
thirty
in longitude’.

The Observatory in Madras, where observations and records stretched back many decades and where the dependable Warren now held sway, was the starting point for all peninsular surveys. Its value in relation to the Greenwich meridian (the zero for longitude) and the equator (the zero for latitude) was the Survey’s sheet-anchor. Madras was in effect the Indian Greenwich. And when, as happened, some infinitesimal adjustment
was made to the coordinates for the Madras Observatory, Lambton’s whole web of triangles had to be realigned.

Other such adjustments would necessitate further mind-boggling recalculations. A later writer estimated that the trigonometrical surveying of India involved 9,230 unknowns and produced ‘unwieldy equations exceeding anything of the kind ever attempted’. Trial and error, leading to constant refinement, played no small part in the geodesist’s science. His situation was like that of a farmer trying to sow his drill evenly with an uncertain number of seeds. When the seeds ran out before he reached the end of the drill, he must needs go back and respace them; and likewise if he came to the end with seeds to spare. Repeating and reviewing past work was as important as prosecuting new work.

For example, the length of a degree of longitude as calculated from that short arc carried south from Madras in 1802 was soon revised when the Great Arc produced a more refined value. That in turn meant that the earliest triangles based on the Madras measurement had also to be revised. As the Arc got longer, other assumptions about the curvature of the earth were reassessed, and these in turn meant more recalculation. Lambton had at first accepted Sir Isaac Newton’s figure of 1/230 for the compression of the earth’s spheroid at the poles. However this ‘constant’ proved anything but. It was revised down to 1/304 in 1812 and by Lambton himself to 1/310 when in 1818 his Great Arc had embraced nearly ten degrees of latitude. Everest in turn would come up with his own constants; and every new constant meant recalculating all previous work.

Further complications arose from attempts to refine standards of length. Lambton’s anxieties over the elasticity of Dinwiddie’s chain increased with every base-line measurement. When the chain unaccountably stopped expanding as measured against the one held in reserve, he became suspicious about the reliability of the latter as a standard. As once before,
a hundred-foot brick wall was constructed, tents erected over its entire length, and its surface levelled and polished ‘so as to resemble a sheet of glass’. Both chains were then stretched along it, their relative values being assessed by micrometer against a standard bar and then marked against pre-set brass studs, mounted in lead, and set in concrete.

Matters were not assisted when in 1821 a parliamentary committee in England laid down a new standard of length. Lambton had long urged the adoption of such a standard, although he would much have preferred that based on the decimal metre and its derivatives as already calculated by the French. The British ignored this advice. In London Henry Kater reduced the new standard to the scale used by Cary in calibrating the dial of Lambton’s Great Theodolite. Lambton had then again to go right through all his measured angles and readjust them.

It was hardly surprising that he had little time for fieldwork. As he patiently explained to the Calcutta authorities, he could not simultaneously continue the surveying and process its results. The calculations involved were so complex that they could be entrusted to no one else. Even producing a fair copy of one of his reports took five months and, because of its highly technical nature, it could not be delegated. Instead he must delegate the fieldwork. If the government were unhappy with this arrangement, they must supply him with a senior assistant; and while they were about it, he also badly needed a doctor and a geologist.

The doctor was required to minister to Lambton’s survey parties, who were continually having to quit the field because of fever, while the geologist was needed to sort out his problems with the plumb-, or plummet-, line. Although the Great Arc was providing satisfactory proof of how degrees along the meridian increased in length as he headed north, they were not increasing by any consistent value; in one case they actually decreased. Similar anomalies had been found on the arcs
measured in France and England and led cynics to suggest that the surveyors were not as infallible they pretended.

But after checking and rechecking, Lambton was sufficiently confident of his own working practices and calculations to look elsewhere for an explanation. The fault, he supposed, lay in the plummet-line, whose vertical was particularly critical in observations conducted with the zenith sector. It was known that the existence of nearby hills might distort the plummet by attraction, another knotty problem as yet unforeseen by Himalayan surveyors. But Lambton now found that even when he was well clear of hills, irregularities still occurred. The worst example of deflection had been at Bangalore, which he could only ascribe to signs of a subterranean ‘vein of dense ore’. And not without a note of triumph he announced that it was this speculation which ‘discovered to us an agent unthought of in former days, viz., a disturbing force occasioned by … diversity in the density of strata under the [earth’s] surface’.