The farther we went the smaller became the river. The Yarkand-darya would never reach the lake, Lop-nor, where it discharges its water, if it did not receive a considerable tributary on the way. This tributary is called the Ak-su, or "White Water," and it comes foaming down from the Tien-shan, the high mountains to the north. After the rivers have mingled their waters, the united main stream is called the Tarim. The weather gradually became colder. One morning a dense mist lay like a veil between the wooded banks, and all the trees, bushes, and plants, and the whole boat, were white with hoar frost. After this it was not long before the frost began to spread thin sheets of ice over the pools on the banks and the small cut-off creeks of stagnant water, and we had to press on as fast as we could to escape being frozen in. Breakfast was no longer laid on land, but on the after-deck of the ferry-boat, where we built a fireplace of clay, and round this the men sat in turn to warm themselves. At night we travelled long distances in the dark. We had persuaded two natives to go with us in their long, narrow canoes, and they rowed in front of us in the darkness with large Chinese paper lanterns on poles to show us where the deep channel ran. The woods on the bank gradually thin out, and finally come to an end altogether, being replaced by huge sand-hills often as much as 200 feet high. This is the margin of the great sandy desert which occupies all the interior of Eastern Turkestan. The people in the country round about are called Lopliks, and live to a great extent on fish. During the last few days of November the temperature fell to 28.8 deg. below freezing-point. The drift ice which floated down the river became thicker, and one morning the ferry-boat lay frozen in so fast we could walk on the ice around it. Out in the current, however, the water was open, and we broke asunder our fetters with axes and crowbars. A constant roar of grinding and scraping ice accompanied us all day long, and during the nights we had to anchor the ferry-boat out in the swiftest part of the current to prevent it being frozen in. On December 7 broad fringes of ice lay along both banks, and all day we danced among drifting ice as in a bath of broken crockery. At night we had a whole flotilla of canoes with lanterns and torches to clear the way, when suddenly the boat swung round with a bump, and we found that the river was frozen over right across. This did not disturb us, for on the bank we saw the flames of a wood fire, and found that it was burning at the camp of our camel caravan. THE WANDERING LAKE