Another fortnight's sailing brought the travellers abreast of a river which flowed slowly and sluggishly into the stream they had ascended, just when its waters had begun to grow clearer and more shallow. It had become more rapid too in its course, and everything suggested that they were gradually gaining higher ground. In addition, in spite of the favourable breezes they enjoyed, the brig could now hardly stem the current. The consequence was that at the captain's suggestion the more sluggish waters of the confluent river were entered, and the fresh course slowly pursued ever northward and westward for weeks, till it became plain that much further progress could not be made in the brig itself. The banks had closed in so that every night the vessel could have been moored to some large tree; but one night's experience of this proved to be sufficient for the travellers, too many of the occupants of the forest giant finding their way on board and interfering with their comfort, and as the vessel swung in the stream boughs of neighbouring trees entangled themselves with the rigging. "It's all right by a wharf," said the captain, "or in a dock; but it won't do here." And in future they always anchored in midstream just before darkness fell. And now, hour by hour, they had warning that their further progress with the brig would soon come to an end. "And it's my belief, gentlemen, that it will be before night," said the captain one morning when they were all seated together beneath the awning chatting. "If you keep quite still, you can hear the stopper." "Stopper? What do you mean?" asked Sir Humphrey, in a surprised tone. He was once more pretty well his old self. "Well, bar, then. There, you can hear it quite plain now." "Do you mean that low murmur?" said Brace, who was listening intently. "I thought it was the wind." "No, sir, it's the water," said the captain. "That's either a fall or else some rapids. I've been noticing lots of little signs of a change lately, and if it wasn't for this steady wind we shouldn't be moving at all. See how clear the water is?" "Yes, I've noticed that it has been gradually becoming clearer," said Brace. "But do you notice that the wind is dropping?" "Yes, we are leaving it behind, and it strikes me that if you like to try about here or a little higher up you'll get some sport." "Then we'll try," said Brace, "when we anchor for the night."