The road now became extraordinarily intricate. Great spurs ran down to the river and blocked the glen, and it was necessary to cut paths through dense forest and thickets of rhododendron to surmount them. There was no track of any kind, and the tributaries descending from the adjacent glaciers were often hard to cross. They ran short of food, and could get no reliable information as to the possibility of their descending the stream. Captain Morshead and the coolies accordingly returned to Gyala, and Captain Bailey, with one man and fifteen pounds of flour, attempted to descend the Tsangpo by the route which a party of Monbas was said to have recently taken. He found the Monbas, but they were wild and suspicious and far from helpful. They refused to take him to their village, and declined to show him the road round the difficult cliffs. Apparently they considered that a traveller who had only one servant, and who carried most of his baggage himself, must be a person of small importance and not worth troubling about. He managed, however, to pick up from them certain news about the lower valley. He returned to Gyala and rejoined Captain Morshead, and they proceeded to piece their knowledge together. At Gyala a small stream drops from the cliffs, making a waterfall, in which the god Shingche Chogye is concealed. The image of the deity is carved or painted in the rock behind the fall, but it is only possible to see it in winter when there is little water. This, apparently, was Kinthup's fall of 150 feet. Now, why should so meagre a natural feature have attained such celebrity among the Tibetans, for the fame of it had spread far and wide over the country? The reason seems to be that it is unique, because there are no other high falls. Had this deduction been made from Kinthup's evidence, the mystery of the Brahmaputra gorges would have been solved long ago. The travellers collected their observations on the altitude of the river level and the speed of the current. At Pe, where they had first struck the Tsangpo, the height was 9,680 feet; thirty-four miles below it the river level was 8,730 feet, giving a drop of 28 feet a mile. At Pemakochung the altitude was 8,380 feet, and the drop 24 feet a mile. Three miles farther down the altitude was 8,090, giving a drop of 97 feet a mile, which included the 30-feet drop of Kinthup's fall. At the lowest point Captain Bailey reached in the river bed the altitude was 7,480 feet, giving a drop of 48 feet a mile. The next point on the river which they had visited was Lagung, below the gorges, where they could not take an observation in the river bed; but forty-five miles downstream the altitude was 2,610 feet.