Trade is the sole foundation of this new Shanghai, and trade 42 depends on the river Hwangpu; for though Shanghai is the outlet for the Yangtse basin, it stands at some distance from the main river and the sea, at the head of the tideway of a small tributary and in close contact with a great network of canals and rivers in the fertile country to the west. The bank of the river is lined with wharves, warehouses and factories, and the Settlement is spreading steadily down towards Wusung. The flat country round has been built up of silt brought down by the main river; centuries ago Shanghai may have been on the coast. The river is still at work: great banks are formed under water, and in a few generations become dry land thickly populated. In the whole breadth of the Yangtse mouth there are only two channels navigable by large vessels. Everywhere the land is gaining on the sea. Into the broad silt-laden estuary the little Hwangpu empties itself below Wusung; it brings down no silt, but the incoming tide sweeps in the muddy water of the main river. The silt is dropped and the stream is too weak to scour it away. At the mouth of the Hwangpu is a great bar, which is still growing; and so much has the channel changed and shallowed that it is no longer safe for the largest vessels to approach Shanghai. We may see the same process going on in England, in the Humber and the rivers flowing into the Wash. The Chinese are at last beginning to move; a new channel has been cut for traffic on the Hwangpu; the bed of the river has been dredged and its course straightened, and an embankment built to keep out the silt from the main river. But the size of the vessels engaged in trade increases every year and the future of Shanghai is in the balance; it remains to be seen whether modern engineering will win the day against the vast forces wielded by the Yangtse. Any decline in the activity of Shanghai would be likely to result in more business for Hongkong.