At about 70 miles from its mouth the Grand Canal reaches the Yellow River, and between the Yellow and Yantsz’ rivers, a distance of 90 miles, it is carried largely upon a raised work of earth, kept together by retaining walls of stone, which are in some places not less than 20 feet above the surrounding country. The width of the channel at this point is about 200 feet, and the current is stated to be three miles an hour. South of the Hwang-ho there are several large towns below the level of these walls, which would be overwhelmed with destruction if they were to give way. From these towns—the principal being Hwai-ngang and Pauying—the canal falls to the Yantsz’, and at Yangchan its level is again below that of the houses on either side. Every stream or lake whose waters can be led into it has a connection with the canal, which has several inlets into the great river Yantsz’, whence navigation is possible for a distance of 2900 miles. East of Chin Kiang the canal leaves the Yantsz’, and proceeds through a rich and fertile country, highly cultivated, and supporting an enormous population, Suchan and Hangchan being among the principal towns on its banks. The northern end of the canal is a channel, 14 miles in length, between Tung-chan and Pekin, which, passing under the city walls, finishes its course of some 600 miles at the palace walls, close by the British Legation. The section between Pekin and the Yellow River is said to have been opened by the Mongols about 1289, by merely joining the rivers and lakes to each other as they now exist. One of the old passages, from Hungtsih Lake northwards, has long been closed, but an attempt has been recently made to open it, so that boats can reach Tientsin from Kwachan. In many works, some of them of considerable pretensions, a great deal more is claimed for this waterway than it really deserves. No doubt there was no work in the world equal to it when it was first opened, and probably in Asia it is still unrivalled. Dr. Williams is correct also in his statement that it reflects far more credit upon the monarchs who devised and executed it than the Great Wall.[134] But the whole structure is crude and primitive in a high degree, compared with more modern canals. Without efficient locks, the canal has to be conducted around the different elevations met with in its course. The boats that use the canal have to be dragged through and up the sluices close to the banks, by large windlasses, whereby they are brought into still water by a very tedious process.