IIIF Color HighRes
National Institute of Informatics - Digital Silk Road Project
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| IIIF Color HighRes |
| In Tibet and Chinese Turkestan : vol.1 |
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Citation Information
COMMENCEMENT OF TRIANGULATION. 2 t
side, then to travel in an easterly direction, avoiding ground which had been visited by others, and to survey a tract of country on either side of the line of march.
In order to get a good value for the longitude of as many places as possible, I had commenced, at Camp 3,
triangulation from a very prominent snow peak, designated Mangtza Lake No. 1 Peak, which had been fixed by the Great Trigonometrical Survey of India, and for the same purpose I now halted close to Horpa or Gurmen Cho.
The theory of determining longitude by triangulation is simple enough, but the practical work is not always
easy. Owing to my want of previous training in the field, I found it difficult to identify peaks seen from various positions, and to remember the exact points that had been first observed in the peaks. The work was retarded
also by the want of trained assistants.
For the accurate measurement of base lines and angles, it was necessary to erect pillars on prominent hill tops from which both ends of the base as well as the surrounding country and other hill stations could be seen. But the men appointed to erect them preferred the slopes of the hills to the summits, though the suitable point was often only a few hundred yards distant. Their preference could not in every case be detected before I reached the spot ; consequently much labour had to be repeated, and the work was rendered unnecessarily complicated.
Ascending the small valley which runs into the northeast side of Horpa Cho, we crossed rising ground and entered a broad valley, bounded on the south by a range of high mountains with prominent snow peaks, most useful in surveying. On the north side of this valley were comparatively low mountains, none of them snowcapped, and through a gap, barely worthy of being desig-
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