Authors: John Keay
Through the winter months of 1824–5, the ground at Sironj was cleared, the chains compared, levels taken, and the coffers and tripods set up for the new base-line. It was Everest’s first. In a constant state of anxiety, as well as pain, he was trundled from end to end. He insisted on supervising every detail and directing every measurement. Such was the pressure of work that he may well have experienced some kind of mental breakdown. Less charitably, he simply drove himself and his companions to distraction. With Voysey and de Penning gone, the brunt fell on Rossenrode and Olliver, the last of the eager young sub-assistants recruited by Lambton back in Madras in the early 1800s. Both were about the same age as Everest and both were now highly experienced. William Rossenrode had worked closely with de Penning and Lambton on the Great Arc, while Joseph Olliver had been with Everest on both the Kistna-Godavari survey and the aborted Bombay longitudinal series. Although someone to whom compliments did not come easily, Everest had been unusually generous in his praise of Olliver’s work. But in his heightened state of paranoia it was
now as if both men were no more than malicious troublemakers.
The inoffensive Olliver was first in the firing line. He was accused of picketing his horse so close to the Superintendent’s tent that it kept him awake all night. This was in direct contravention of an order that ‘neither men nor cattle should make any sort of disturbance within my hearing.’ Did Olliver not appreciate that, in his present state of health, he required every minute of sleep that he could get? Indeed Olliver did, and he denied the charge; but the neighing continued. It went on for three consecutive nights. Someone was obviously enjoying himself. At his wits’ end, Everest ordered a guard to pad softly through the camp during the hours of darkness and to turn loose or shoot on sight any stirring quadruped. Peace then reigned, although the mystery remained.
Six weeks later, in November, the unfortunate Olliver was again in trouble. While overseeing some construction work at the far end of the base-line, he had prevaricated over a request that he help Everest with the zenith sector. Everest interpreted this as rank insubordination. His principal sub-assistant, the man whom he had once described as ‘my right arm’, was summarily arrested, placed under guard, and reported to Calcutta. Luckily Everest’s superiors knew of his temperament. A reconciliation was urged and Olliver, after apologies, was reinstated.
His case was probably helped by the discovery that it was in fact Rossenrode who had been responsible for the phantom horse which neighed all night. ‘You were that person; and it was a horse of yours which created the nuisance,’ bellowed Everest when the truth leaked out. Rossenrode at the time was busy working out the mean average of various astronomical values. Resenting the interruption, he responded in kind. Indeed Rossenrode’s outburst, being according to Everest ‘more befitted to a lewd scold in the purlieus of Billingsgate or Wapping than to a person who had been accustomed to
the decencies of life’, was deemed more heinous than the original crime. Everest again threatened arrest and disgrace.
It seems, though, that the matter blew over, somewhat literally, when on 10 February 1825 the camp was hit by a minor typhoon. In a foretaste of the winters to be expected in the north, rain and hail accompanied a wind so strong that it flattened all the tents, including that which housed the Great Theodolite. Neither the double guy-ropes nor the ten men who were hanging on to them could do anything about it. As the tent went over, so did the great instrument, crushing beyond redemption ‘one of the beautiful Troughton barometers’ which happened to be standing nearby. ‘Fortunately,’ reported Everest, ‘[the Great Theodolite] has received no other injury than the breaking of one of the lower screws which I have the means of repairing.’ But this may have been a misleading assessment of the damage. In another context Everest describes the timber frame of the theodolite as splitting and the whole thing as being ‘sadly ricketty’. Almost immediately after the accident the instrument was packed away and no one was allowed to use it. Except for an outing to measure a single angle in 1826, it was not used again until 1835, by which time an expert instrument-maker from England had completely rebuilt it.
In 1825 Everest himself had had no further use for it. With the Sironj base-line completed and his health more precarious than ever, in March he finally indented for sick leave in England. He sailed from Calcutta later that year and, having been assured that his job was safe in his absence, did not reappear in India until five years later.
Allowing one full year for the voyages home and back, five years was still a long absence. To retain his position and at least part of his salary, it was necessary to prove that in Europe, as well as recuperating, he would be busy about the Survey’s business. He therefore took with him sufficient documentation to work up the results of his last two years’ work and to write
an account of it. On arrival in London he also began visiting instrument-makers and indenting for the latest in the way of survey apparatus. Besides theodolites and zenith sectors, he inspected lamps for night work and a sun-reflecting mirror, variously known as a heliostat or heliotrope, for daytime sighting. His employers, the directors of the East India Company, were not immediately impressed by this shopping spree. But Everest had powerful patrons and was able to mobilise the support of the scientific establishment following his election to Fellowships at both the Royal Society and the Royal Astronomical Society. The new instruments were finally sanctioned and he was soon busy driving their makers to distraction with a long list of modifications.
During his absence from India the post of Surveyor-General with responsibility for all Indian surveys other than the Great Trigonometrical Survey fell vacant. Well-placed to press his own credentials, in 1829 Everest secured his appointment to this most senior position and would thus return to India as both Superintendent of the Great Trigonometrical Survey and Surveyor-General in charge of all topographical and revenue surveys. These new responsibilities could have proved a distraction from his triangulations and in particular from the Great Arc. In fact they would stimulate them, since the resources of the other surveys would be increasingly redirected to the Great Trigonometrical Survey.
Home leave proved timely in other ways. At the instigation of Richard Wellesley, now Marquess of Mornington and Lord-Lieutenant in Dublin, the British Ordnance Survey had recently been entrusted with a detailed survey of Ireland. The Master General of Ordnance was Richard’s brother Arthur, now Duke of Wellington and Prime Minister. Unsurprisingly, given such patrons, the Irish survey was being conducted on an unprecedented scale, to witness which Everest spent three months in its company. He noted particularly its institutional structure and instruments; and he also observed with interest
the thirty officers, the three hundred other ranks and civilians, and the like number of labourers thought necessary for what was indeed an ambitious but basically straightforward trigonometrical survey of an island rather smaller than the state of Hyderabad.
Clearly, in the light of this Irish revelation, it would not be out of order to request more personnel for his Indian operations and to expect better funding. He also noted how in Ireland the trigonometrical measurement was deemed a prerequisite for all other surveys, something which in India was often professed but, because of the variety of other demands and because of the existence of other surveys, was rarely practised. Here was the justification he needed, as Surveyor-General, for according priority to the Great Trigonometrical Survey and his beloved Arc and concentrating all resources on them. Additionally he remarked the ease with which the Irish surveyors could get their instruments repaired and checked; an instrument-maker for India was requested and duly supplied. And finally, besides all the other instruments he had ordered, he obtained a double set of ‘compensation bars’ to replace the chains hitherto used for measuring baselines.
Compensation bars had been developed by Thomas Colby, the Ordnance Survey’s Surveyor-General who was now conducting the Irish operations. Because of the familiar problems of chains expanding in the heat and becoming worn with use, Colby had experimented with twin bars, each ten feet long and each composed of a different metal whose different rates of expansion could be made to cancel one another out mechanically. Compensation bars thus consisted of two bars, one of brass and the other of iron, aligned side by side, bolted together in the middle, and with a cunning little attachment, like a side-bolted lever, linking the bars at each end. As the iron bar expanded it caused the lever to pivot about its axis on the less expansive brass bar so that a dot marked on the lever’s
projecting ‘handle’ remained in the same place. The bars were supported on brass rollers and housed in a wooden case from which the levers with the dots on them protruded. Six such sets of bars comprised the usual complement and, once set up and joined together by their accompanying microscopes, gave a length of sixty-three feet.
Everest was highly delighted with them. Before leaving for India in 1830 he tested the new apparatus in London, finding just the flat surface required at Lord’s Cricket Ground. He repeated the experiment in Calcutta soon after his arrival in 1831, and later that year he commenced in earnest the measurement of a six-mile Calcutta base-line.
Calcutta, of course, was nowhere near the Great Arc. But as the seat of government, it was the perfect place in which to impress British India with the demanding nature of the Great Trigonometrical Survey and of the superior science which was being invested in the Great Arc. Additionally, the base-line was a necessary means of verifying the accuracy or otherwise of the work which had been undertaken in Everest’s absence.
While he had been on leave, Joseph Olliver, assisted by the rebellious Rossenrode, had been given the task of carrying a triangulation eastwards from Sironj, where the Arc currently terminated. Everest had refused to entertain the idea of those whom he called Lambton’s ‘mestizoes’ being entrusted with the Arc itself, but in this eastward series he had seen a useful way of keeping his men together and of incorporating Calcutta into his grid-iron of triangulation. Known as the Calcutta Longitudinal Series, it was, in effect, the equivalent of the Bombay Longitudinal Series on which he himself had been working when Lambton died in 1823. The distance, however, was longer – nearly seven hundred miles in this case – and the terrain more challenging. Initially it had consisted of formidable jungle, in which one of Rossenrode’s sons had died and whence the entire survey had had to be repeatedly rescued in
a state of malarial collapse. Thereafter the Survey descended into the Gangetic delta in west Bengal and had progressed to within about seventy miles of Calcutta by the time Everest reappeared. The new base-line would complete this work and, when connected up to it, would reveal its accuracy.
But there were good reasons for supposing that the result would be disappointing. For one thing, Olliver had been denied the use of the thirty-six-inch Great Theodolite and, instead, had had to make do with an eighteen-inch instrument of inferior design. Comparing the telescopes of the two, Olliver found his smaller instrument useless for distances of more than about twenty-five miles. His triangles were consequently cramped and his trig points numerous. Considering that the overall distance of seven hundred miles was much the longest yet undertaken without an intermediary base measurement, Everest can hardly have expected the highest standard of accuracy. Indeed one wonders at his subsequently adopting Olliver’s series as the basis for a succession of meridional arcs – the ‘bars’ of his grid-iron – running up to the Himalayas.
Another problem with which Olliver’s men had had to grapple was that of extending a trig survey across a flat landscape covered in trees and blanketed in a soupy haze. Bengal was part of the Gangetic plain, the long-feared obstacle across which trigonometrical surveying was thought impossible. Perhaps unwittingly, Olliver was being used as guinea pig. By sighting at night to lights, Everest had shown that mists could be penetrated, but it was still necessary to attain vantage points from which to see over the leafy canopy. With ladders lashed to branches, one above the other, Rossenrode and his men in the advance party had climbed sixty to eighty feet into the trees. Still they could get no clear view, added to which ‘the dread of tigers was so great that the Bengali labourers would at every rustle of the dry leaves throw down the ladders and disperse in all directions’.
Scaffolding towers were tried with greater success, but they required much timber and labour, and it was almost impossible to make them stable enough to observe from. They moved in the slightest wind and, because of the difficulty of managing both lights and instruments on a flimsy little platform ninety feet above the ground, night work was found impossible. Much better were masonry towers, and in this respect Olliver was fortunate. A line of just such towers fringed the northern edge of his series through western Bengal and so provided half of his requirement. The towers had been built early in the century as a part of a primitive, pre-electric telegraph system by which messages, preferably short ones, could be flashed up-country from tower to tower. Everest had himself worked on the telegraph towers before being posted to the Great Trigonometrical Survey in 1818 and, no doubt, had been reminded of them when constructing those outsize cairns on his Bombay series.
The telegraph towers required some modifications for survey use, but the expense was as nothing compared to that of constructing new towers. Nevertheless, after his return Everest found that to complete the Calcutta series it was necessary to build eleven additional towers. Several designs were tried, and the cost was indeed considerable. But crucially it was this experiment which convinced him of the feasibility of continuing the Great Arc north from Agra (as and when it got there), across the plains to Delhi, and on to the Himalayas. Instead of
droogs
and temples and tousled hills, the Great Arc would approach the mountains by way of a chain of specially-built masonry towers. And so, provided the funds were forthcoming, the last great barrier to making the Arc an India-long measurement could be overcome.