"Yes," said Mr. George; "but that current is the tide, coming in from the sea. This way is down towards the mouth of the river. See all this shipping here! It has come up from the sea." Here Mr. George pointed with his hand down the river, waving it from one side to the other, so as to direct Rollo's attention to both shores, where there lay immense forests of shipping, three or four tiers deep on each side, and extending down the river as far as the eye could penetrate into the thick and murky atmosphere. Besides the tiers of shipping which lay thus along the shores of the river, there were two other ranges, each three or four tiers wide, out in the stream, leaving a broad, open passage between them, in the middle, and two narrower passages, one on each side, between them and the shore. "It is a city of ships," said Rollo, "with streets of open water." "Yes," said Mr. George, "it is indeed." The streets, as Rollo called them, of open water, were full of boats, going and coming, and of lighters and wherries, with a steamer now and then shooting along among them, or a large vessel slowly coming up or going down by means of its sails. "This is the way _down_ the river," repeated Mr. George. "The ships have come up as far as here; but they cannot go any farther, on account of the bridge. Look above the bridge, and you will see that there are no ships." So Rollo and Mr. George turned round to look up the river. They could only catch an occasional glimpse of the river through casual openings in the stream of carts, carriages, vans, cabs, wagons, and omnibuses that were incessantly rolling on in opposite streams along the roadway of the bridge. Although the view was thus obstructed, they could easily see there were no ships above the bridge that they were standing on. There were, however, several other bridges farther up, with a great many boats passing to and fro among them; and, here and there, there appeared a long and sharp-built little steamer, gliding swiftly through the water. These steamers were painted black, and they poured forth volumes of smoke so dark and dense from their funnels as quite to fill the air, and make the whole prospect in that direction exceedingly murky and obscure. "Let us go over to the other side of the bridge," said Rollo. "Not yet," said Mr. George; "but you see that there is no shipping above the bridge. Vessels _could not_ go up above the bridge, in fact. They could not go up, for the masts are too long to pass under the arches." "They might have a draw in the middle of the bridge," said Rollo.