"Now," continued Mr. George, "a ship comes in, we will suppose, and is to be taken into the canal. First, the men open the sea gates. The sea can now flow into the lock, but it cannot get into the canal, because the canal gates are still shut."
"Yes," said Rollo.
"And, now you see," continued Mr. George, "that as the water in the lock is high, and on a level with the sea, the ship can sail into the lock."
"But it can't get down into the canal," said Rollo.
"No," replied Mr. George, "not yet. But now the men shut the sea gates, and thus shut the ship in. They then open the passages through the canal gates, and this lets the water out of the lock until it subsides to the level of that in the canal, and the ship settles down with it. But the sea cannot come in, for the sea gates, that are now behind the ship, are shut. When the water in the lock has gone down to the canal level, then they can open the gates, and the ship can sail along out of the lock into the canal.
"Thus they lock the ship down into the canal at one end, and when she has passed through the canal, they lock her up into the Y again at the other."
"Yes," said Rollo. "I understand it now. And shall we go into the canal through the locks in this way?"
"I don't know," said Mr. George. "I'll ask James."
So Mr. George beckoned to James to come to him, and asked him whether they should enter the canal through the lock.
"No," said James. "The ferry boat does not go into the canal at all. We go into a little dock or harbor by the side of it, and the passengers walk over the dike, and down to the canal, where they find the boats ready for them that they are to take."