[4] A tropical wood of extreme lightness. With her help we soon had several good-sized balsa logs ready, and by sundown we had practically finished a sort of combination raft and catamaran that would, I felt sure, serve us on the stream as long as we did not meet rapids or falls. The next morning we embarked, and thereafter, for days, we drifted swiftly, easily, down river without adventure, without effort. * * * * * TWICE, as we swept past cliffs, we saw the symbols pointing ever onward, and despite myself I, was forced to admit that, regardless of how it had been done, old Nohul Voh had revealed the truth to me when he had showed me the “Way of the Symbols.” So, being now convinced that it was so, I kept a sharp lookout for the precipice in whose base was the black tunnel through which the river flowed in the vision. Each day, as we drifted on, the mountains receded and became lower. Each day the river broadened, and I was constantly expecting to see Indian huts or villages and was as constantly surprised to find the country apparently uninhabited. Game was abundant, the stream was filled with fish, and though Itza missed the vegetable food to which she had always been accustomed, still she made no complaint and remained well and strong. Often she laughingly twitted me on having pictured such bugbears of dangers and hardships. Since leaving the Cave of the Bats it had all been easy, safe, glorious fun to her. But we were not at the end of our journey yet, I told her. Then, at last, one day we saw the expected mountain side stretching across the valley ahead, and presently, as we drew near, the black archway at its base was visible, exactly as I had seen it in my vision. By now I had become so thoroughly convinced of the accuracy of that glimpse into the unknown, that I felt perfectly sure that we would pass through the tunnel and emerge on the farther side in safety. But unfortunately the smoke-screen had not shown me the craft in which I was voyaging. Still, our balsa wood raft had proved most efficient, there was no sign of rapids or falls ahead--although the current increased and ran swiftly into the tunnel. But I was not taking any unnecessary chances. Running the raft ashore, I made it fast, and, with no little difficulty, made my way down stream until within a few feet of the opening in the cliff. But though we both listened intently, we could hear nothing that sounded like rapids or a fall--just a low, rushing, steady roar. Only one peril, I felt, remained. Could I feel sure that there was space enough between the surface of the stream and the roof of the tunnel for our craft and ourselves to pass? Fully ten feet of space showed at the entrance, but could I be certain it did not decrease within?