The first rigorous survey undertaken in the neighbourhood was that carried out by Captain C. H. D. Ryder, R.E. (now Colonel Ryder, C.I.E., D.S.O., Surveyor-General of India), during the Tibet Mission of 1903–1904. During the stay of the Mission at Kampa, the ¼-inch survey was carried as far West as longitude 88°; while, on the subsequent return march up the Tsangpo Valley, surveys were extended as far as the Southern watershed of the great river—the so-called Ladak Range—in latitude 29° approximately.
West of longitude 88° there thus remained a stretch of unsurveyed country some 14,000 square miles in area, between the Ladak Range on the North and the Great Himalaya Range on the South—the latter forming the Northern frontier of Nepal. The Mount Everest Expedition provided an opportunity of making good the whole of this area, with the exception of some 2,000 square miles at the extreme Western end, into which, in view of the restrictions of the Indian Foreign Department, I did not feel justified in penetrating.
Fortunately, Colonel Bury's plans contemplated an outward Northerly journey via Shekar and Tingri to the Western flanks of Mount Everest, whence the reconnaissance of the mountain was to be carried out from West to East, parallel to the Northern frontier of Nepal. This rendered feasible the mapping of the whole unsurveyed area between the Southern watershed of the Tsangpo and the Great Himalaya Range, as far West as longitude 85° 30', without in any way infringing the Foreign Department's orders and restrictions.
For the purpose of the detailed survey of the Mount Everest regions, it was arranged for my Assistant, Major Wheeler, to make a thorough test of the Canadian pattern of photo-survey apparatus, of which he had had previous experience in the Canadian Rocky Mountains. This method of survey, which had not hitherto been employed in India, is particularly adapted for use in high mountain regions. Fortunately, the experimental outfit, which had recently been ordered from England, was delivered just in time to accompany the Expedition. Wheeler's account of his season's work will be found in Appendix II.
With a view to carrying out the revision survey of Sikkim while awaiting the arrival of the members of the Expedition from England, the Survey Detachment was authorised to assemble at Darjeeling early in April, six weeks before the date fixed for the start of the Expedition. In spite of an unusually wet and cloudy spring, the three surveyors made such good use of their time that 2,500 square miles of country were completed before the advance of the Expedition necessitated the temporary abandonment of this work.
After completing the necessary preliminaries with Colonel Bury, I myself left Darjeeling on May 13, intending to rejoin the remainder of the Expedition in Sikkim. Continuous rain, however, rendered the latter task impossible; the Sikkim roads were, moreover, blocked in several places by severe landslips, so that I was only with difficulty able to reach Kampa by the 28th. It transpired, however, that there was no cause for hurry, since the main body of the Expedition, travelling via the Chumbi Valley, had encountered greater difficulties than mine, and did not arrive at Kampa until June 5. While awaiting their arrival, I filled in the time by occupying and re-observing from Colonel Ryder's old triangulation stations of 1903, overlooking the Kampa Plain.
I had received no news whatever of the Expedition or of the outside world since leaving Darjeeling three-and-a-half weeks previously. Consequently the death of my old friend Dr. Kellas on the very day of their arrival at Kampa came to me as a very severe shock.
The Sikkim revision-survey having been so much hampered by bad weather, I decided to take only two of the three surveyors with the Expedition into Tibet, leaving Surveyor Turabaz Khan to complete the comparatively dry areas of Northern Sikkim before the arrival of the monsoon. This he succeeded in doing at the cost of considerable personal discomfort, returning to Darjeeling in July.
It was not until we reached the summit of the Tinki Pass on June 11 that we found ourselves for the first time looking into unsurveyed country. From here onwards as far as Tingri the survey was kept up by Lalbir Singh, whose unflagging energy alone enabled him to keep pace with the long marches of the Expedition. Each morning he was away with his plane-table and squad of coolies long before our breakfast was served, seldom reaching camp before nightfall. The gathering clouds and other ominous signs of a rapidly approaching monsoon, however, forbade any respite.
On arrival at Tingri, after spending a week in fruitless efforts to observe the triangulated peaks of the main Himalayan Range through the dense monsoon clouds which were daily piling up more and more thickly from the South, I departed on June 26 with Surveyor Gujjar Singh on a short trip to explore and map the upper valley of the Bhong Chu.