60 r THE MAPS [Chap. Ili.
need of special explanation. 1 Others which had to be specially introduced for the marking of ancient sites, ruins and other objects of antiquarian interest, are sufficiently explained in the. table of symbols reproduced at the foot of each sheet.
No exact chronological limits can be fixed for the `antiquity' which the use of red
populous are made recognizable by slightly enlarged solid blocks. The market-towns of village tracts in the T'ârim basin are easily recognized by the addition of -bdrdr (often coupled with a week-day) to the name of the tract. In Kan-su where practically all villages and hamlets are walled, the use of the fort symbol has been restricted to small towns to avoid over-crowding. Throughout the maps a sm^11 open square has been used to distinguish temporarily occupied structures such as roadside stations (lanyar), shepherds' huts (i ykil), and the like, from permanent habitations.
As in the 1/Million sheets of the Survey of India, no distinction has been made between different classes of roads, except that the few main lines of
Representation of traffic connecting the principal oases and usually marked by the Chinese
administration with `mile-stones', recta mud towers, at distances of 10 li (approximately 2 miles) have been shown with double lines in red. Throughout the regions represented, `roads' are only natural tracks, practicable for camels everywhere in the plains and for carts also, except where the stretches of drift-sand to be crossed are extensive, as is the case all the way between Khotan and Tun-huang.
In regions where desert areas vastly predominate, some difficulty is naturally experienced as to which tracks can reasonably be marked as 'roads and paths'. Indication of tracks.. Tracks such as those which traverse the western K uruk-tâgh or lead along the foot of the easternmost K'un-lun, though well-known to more venturesome people in the nearest small settlements, may remain unused for many months, or even years. The principle I have endeavoured to observe was to mark with the red line of 'road or path' only those tracks which an experienced traveller in possession of the map might witk duce care be able to follow unguided. It goes without saying that of such tracks, too, many are liable to be lost in places when unfavourable atmospheric conditions obscure landmarks, etc.
Within the oases, on the other hand, well-trodden tracks between villages and hamlets are so numerous that it would be impossible to show them all on the scale of our maps. Hence within cultivated ground it has often been found necessary for the sake of clearness to show only the routes followed, without marking the roads along which they led. s
Special care has been taken to mark all routes along which survey work was done, by rows of small crosses, the colours black, blue and red being used to
Marking of surveyed
routes. distinguish routes followed on the first, second and third expedition
respectively. Where the same route was surveyed on more than one journey, crosses of corresponding colours have been used alternately. The successive route stages on each journey have been shown by the insertion of 'camp numbers' in the same distinctive colours as the routes to which they refer; a special camp symbol was added where the stage lay at a spot away from any habitation. The numerical order of camps makes it possible to follow the direction in which the survey on each route proceeded. On the first and second expeditions, routes surveyed by myself only are recognizable by `camp