"The tide is still on the ebb, so we will keep in near the trees," called Tyler gently, as they swept away from the bank. "By doing so we shall have less difficulty in making good progress, for the current will be less swift. A glance overhead will always tell you whether we are keeping the right course, and as you will be the first to notice when we go astray, just call to me so that I may know it. Now, in with the paddles."

Keeping time with one another, they sent the light boat up the stream at a good pace, and when an hour had gone had the satisfaction of knowing that they had made excellent progress, while half an hour, perhaps, of darkness remained to them. And now their course was shaped for the bank, for they did not dare to run the risk of being observed. Very soon they came to a part where the trees grew close down to the water, and here they remained till the day dawned, clinging to the boughs so that the stream should not carry them down again.

"It is light enough to see now," said Tyler at length, "and we will push in and take up a position from which we shall be able to see without being observed by people who may be passing on the river. Lift the boughs gently, Li, and pull us in. That's the way. Now we are in open water again, though it is only a narrow stretch, and can use our paddles."

Gently propelling the craft, they sent her on beneath the low-hanging boughs, and finally came to a halt when they had traversed about half a mile of the leafy avenue. And here they made fast with the painter and at once began to eat, for there was no saying when they would have another opportunity. Then they turned their faces to the river and peered from amongst the covering, being able to see right across the river.

"We have a long row before us, and have need of all our strength," said Tyler, "and for that reason we will take it in turns to rest, for this night-work is very tiring. You lie down, Li Sung, and I will wake you later on."

And so, whilst one kept watch on the river, noting the boats which passed, the other slept, the following night finding them both refreshed and prepared for the work before them. Issuing from the trees they once more took to the stream, and when the following day was at hand were in the neighbourhood of Rembas, the lowest of the piratical strongholds.

"What is that?" demanded Tyler suddenly as they lay on their paddles, staring at the opposite bank, and wondering whether or not they were opposite Rembas. "I heard a sound behind us, and I am sure that it did not come from the bank."

Both sat up and listened eagerly, only to turn to one another in perplexity, for neither could fathom the nature of the sound which had caused them alarm.

"It is a curious hissing," said Tyler in troubled tones, "and as I said before, I am sure that it comes from the direction of the mouth of the river. But what can it be? To me it sounds like water."