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Digital Archive of Toyo Bunko Rare Books

CHAPTER I

HISTORY OF THE SURVEYS

Section I.—GENERAL CHARACTER OF THE TOPOGRAPHICAL WORK

The main facts concerning the surveys effected on my three Central-Asian expeditions
and many of the more notable incidents and results which attended them have been already
recorded in the 'Personal Narratives' and 'Detailed Reports' published by me of the first
two journeys¹ or, as regards the third, in the fairly comprehensive preliminary account
printed in the Royal Geographical Society's Journal.² I shall accordingly restrict myself
here to notes on the character and range of the surveys made of each journey; on the assistance
available for the topographical work of each, and on the routes along which this work was
carried, distinguishing the routes upon which the surveys were effected under my personal
supervision from others where the operations were conducted by my assistants or myself
alone.

Before however recording these details for each successive expedition it will be conve-
nient here to indicate essential points regarding the methods which
Methods in surveys. were uniformly observed in all our surveys. As already stated above,
these methods were the same as those employed by the Survey of India
for 'reconnaissance survey' work. They implied continuous plane-tabling along all routes
followed, supplemented throughout by astronomical observations for latitude and by triangu-
lation rendered possible in particular areas by proximity to previously fixed points, by the
configuration of the ground, available time and similar considerations.

Except on the journey of 1900-01 when a scale of 8 miles to 1 inch was used, the
surveys were on the scale of 4 miles to 1 inch, this having proved by
Scale, etc., of plane-
table work. experience on the ground to be the most convenient for adequate record
of topographical detail under our conditions of travel. On mountainous
ground no efforts were spared to place plane-table stations on commanding heights above
passes and route lines, maximum elevations of nearly 20,000 feet being climbed by us in
the K'un-lun for this purpose and of over 16,000 feet at numerous points of the Pamir and
Nan-shan ranges. In the great plains of the Tarim basin and in the similar drainageless
deserts eastwards, the flatness of the ground, the absence of recognizable landmarks and
the peculiar dust-laden condition of the atmosphere, persisting for prolonged periods, made
it very often impossible to fix positions by intersections or triangles. On this ground the
exact measurement of distances which the use of the cyclometer invariably carried on the
second and third expeditions permitted, was essential for the plane-table traverses.

For the purpose of securing points to check these traverses, astronomical observations
for latitude were made by my assistants with a 6-inch transit theodo-
Latitude observations. lite at frequent intervals when atmospheric conditions and available time
permitted. These observations were beset with serious difficulties, both
on account of climatic conditions and the rapidity of movement necessitated by other
scientific tasks and the wide extent of difficult ground to be covered. Prolonged periods of