elsewhere along this section, the wall—for so it may well be called considering its solid construction —was found to be built solely of stout tamarisk branches thickly packed, without any distinguishable layers of earth. For about a mile and a half it ran on continuously, still keeping a height of io feet at the end and being 71 feet wide at the top. It looked doubly impressive in this sandy waste, as a monument of constructive ingenuity and perseverance in truly forbidding surroundings. Beyond this it could be traced only as a low swelling of the ground, without any wood showing on the surface, for about three-quarters of a mile. Then we finally lost it among tamarisk-cones, close set but not of great height.
Nowhere along the line thus surveyed by us were remains of towers or other marks of early occupation to be observed. It is, of course, possible that decayed mounds marking towers and small patches of refuse or pottery debris may lie hidden below the sand and thus completely escape notice. But the nature of the ground and the peculiar method of construction here adopted permit of another explanation being offered of this total absence of marks of former occupation. The difficulty of securing water which this very method of constructing the agger indicates may soon have convinced those who directed the operation of the practical impossibility of maintaining regularly occupied watch-posts in this region. In that event they might well have contented themselves with having the Limes wall constructed, as it stands now, without towers, and arranging for its protection solely by patrols from stations farther south placed in convenient proximity to water.
However this may be, it is certain that the ground over which the line of the Limes had been carried from here eastwards as far as the terminal course of the Pei-ta-ho (Map No. 42. c. 4), where we subsequently traced it, a direct distance of over forty-five miles, must have been a barren waterless waste of drift-sand or gravel Sai ever since ancient times. The fact that the Limes had been boldly carried into, and through, this truly forbidding area was striking proof that those responsible for its construction were prepared for great and sustained efforts in the face of formidable natural obstacles. Yet it was impossible to behold this impressive monument of their energy without being moved by the thought of the immense amount of human suffering which the execution of the imperial frontier scheme in this desolate region must have entailed.'
After crossing a chain of dunes 4o to 5o feet high and proceeding southward for nearly four miles from the point where we left the wall, we came upon a decayed mound about 7o feet long and half as much across ; an enclosure some 94 yards square, built of brushwood bundles (see plan, T. XLIV. e, PI. 16), adjoined it. There was evidence of its having served as a herdsmen's station, and the potsherds lying about on the surface (see List) appeared to be of a late period. But only a thorough examination, for which there was neither time nor means, could have shown whether the remains of some ancient post connected with the Limes was concealed under the debris accumulated as a result of more recent, if intermittent, occupation by herdsmen. Farther south, on ground probably reached by occasional rain floods, grazing was abundant, and there, about two miles from our camp, we found a well 16 feet deep, which, as mud-built hovels near by showed, is still frequented by herdsmen.
We may now turn back to T. XLIV. a, the northernmost of the series of ancient watch-towers previously mentioned as standing distinct from the Limes wall but stretching towards it. T. XLIV. a attracted our attention from afar, owing to its size and comparatively fair preservation. It was found to measure 32 feet square at the base and to rise to 14 feet above a low plateau of gravel. It was built of layers of clay, 6 or 7 inches thick, and thin brushwood layers between. On the eastern side a small structure appears to have adjoined it ; the debris of its walls, mingled with
1 For the reflex in Chinese poetry of the deep and lasting sacrifices incurred for the defence of China's desert borders,
impression that has been left on the popular mind by the cf. Chavannes, Documents, pp. xxi sqq.