Esmeralda Island was formerly joined at its most south-westerly point to the western bank of the river. From that point the river described an arc of a circle as far as bearings magnetic 20° (N.N.E.). We negotiated successfully two small rapids with large volcanic rocks just under the surface of the water. We just escaped going over one of them, which would have certainly capsized the canoe. As it was we merely scraped the side of the canoe against it.
The left bank, which had crumbled down, showed strata of conglomerate and yellow sand, with upper alluvial deposits of a light grey colour.
We were travelling due north in a straight line of 1,800 m. when we came upon the entrance of a lakelet on the west side of an islet. A huge fish—some 5 ft. in length—unaccustomed to the unusual sight of human beings, played about under our canoe for some time, much to the excitement of my men. Birds of superb metallic blue, vivid yellow, and iridescent plumage played about among the trees. On the left bank farther down was a great growth of high bamboos, then again forest with plenty of vigorous rubber trees.
Again small and fairly swift rapids were encountered in a turn of the river from bearings magnetic 70° to 250°. A tributary stream which came from the south entered the Arinos on its left bank. Then we came to another island forming two channels—one (N.W.) 20 m. wide, with some rough-looking rapids; the other channel (N.), larger and shallower, divided in its turn in two by a mound of yellow gravel.
Alcides, who steered, had an idea that in going down rapids you should always send the canoe over places where the water broke and foamed, which meant rocks underneath, and not keep her in the centre of the channel where the water was deeper. This idea was, I think, suggested by his inability to swim, and the hope that if we got wrecked he could touch bottom with his feet, so that his life might be in comparative safety. I tried to argue the point with him, but it was no use. It invariably led to such unpleasantness that once more I decided to trust in Providence, as long as we went forward.
I had just shouted to Alcides to keep in the centre of the channel. Of course he disobeyed. We were caught in the strong current. One moment later there was a violent bump which knocked us all off our seats and sent us sprawling in the bottom of the canoe. We had stuck fast between two rocks. The canoe, being of such great length, vibrated to and fro with the current forcing it at the side. Laden as she was with baggage, in a few moments she became filled with water, and it was only after working hard for the best part of an hour that we were able to extricate ourselves from our position. We had hardly finished baling the water out on resuming our course than, 1,500 m. farther, we came to more rapids, then 700 m. beyond yet other rapids.
The forest was fairly thick all along on both banks, with innumerable healthy rubber trees. Although the forest seemed impenetrable at first sight, I always found that it was easy enough to go through it if one knew how. Quite close to the water naturally the vegetation was somewhat entangled. In many places were extensive patches of bamboos of considerable height; but there is a way of disentangling the most confused growth, if you happen to understand how those plants and liane grow and get twisted. Any one with a keen sense of observation should experience no difficulty whatever in going through the densest forest anywhere in the world—even without using a knife—although, of course, the latter is useful when you wish to keep up a certain speed in your marching.
Eleven kilometres and a half from the last rapids—having travelled north-west, south-west, east, and even due south, so winding was the course of the river—we came to a tributary stream 10 m. wide, on the left side of the Arinos. Eight kilometres farther we passed the inlet—then dry—of a small lagoon fed by the stream. The river banks, where eroded by the water, showed a lower layer of reddish-brown rock with a bright red ferruginous stratum above it. The top layer, 10 ft. thick, seemed formed of lime and alluvial deposits.
We emerged into a large basin 200 m. across, with a charming little island in the centre forming two channels with fairly strong rapids. We followed the channel on the right. At that point the river folded over itself into a great elbow. A cliff, 120 ft. high, towered on one side in brilliant red and yellow. The lower half of the strata was perfectly horizontal; the upper half at an angle of 45° to the lower. The vivid colouring was intensified by contrast with a beautiful beach of immaculate white sand on the left side of the great elbow.
I observed a wonderful double lunar halo on the night of July 7-8, the outer circle in successive tints of most delicate yellow, orange, pale blue and white—the yellow being nearest the centre.