With these began a series of half a dozen sets of rapids, all coming within the next dozen kilometres, and all offering very real obstacles.  At one we saw the graves of four men who had perished therein; and many more had died whose bodies were never recovered; the toll of human life had been heavy.  Had we been still on an unknown river, pioneering our own way, it would doubtless have taken us at least a fortnight of labor and peril to pass.  But it actually took only a day and a half.  All the channels were known, all the trails cut.  Senhor Caripe, a first-class waterman, cool, fearless, and brawny as a bull, came with us as guide.  Half a dozen times the loads were taken out and carried down.  At one cataract the canoes were themselves dragged overland; elsewhere they were run down empty, shipping a good deal of water.  At the foot of the cataract, where we dragged the canoes overland, we camped for the night.  Here Kermit shot a big cayman.  Our camp was alongside the graves of three men who at this point had perished in the swift water.

Senhor Caripe told us many strange adventures of rubber-workers he had met or employed.  One of his men, working on the Gy-Parana, got lost and after twenty-eight days found himself on the Madeirainha, which he thus discovered.  He was in excellent health, for he had means to start a fire, and he found abundance of Brazil-nuts and big land-tortoises.  Senhor Caripe said that the rubbermen now did not go above the ninth degree, or thereabouts, on the upper Aripuanan proper, having found the rubber poor on the reaches above.  A year previously five rubbermen, Mundurucu Indians, were working on the Corumba at about that level.  It is a difficult stream to ascend or descend.  They made excursions into the forest for days at a time after caoutchouc.  On one such trip, after fifteen days they, to their surprise, came out on the Aripuanan.  They returned and told their “patron” of their discovery; and by his orders took their caoutchouc overland to the Aripuanan, built a canoe, and ran down with their caoutchouc to Manaos.  They had now returned and were working on the upper Aripuanan.  The Mundurucus and Brazilians are always on the best terms, and the former are even more inveterate enemies of the wild Indians than are the latter.

By mid-forenoon on April 26 we had passed the last dangerous rapids.  The paddles were plied with hearty good will, Cherrie and Kermit, as usual, working like the camaradas, and the canoes went dancing down the broad, rapid river.  The equatorial forest crowded on either hand to the water’s edge; and, although the river was falling, it was still so high that in many places little islands were completely submerged, and the current raced among the trunks of the green trees.  At one o’clock we came to the mouth of the Castanho proper, and in sight of the tent of Lieutenant Pyrineus, with the flags of the United States and Brazil flying before it; and, with rifles firing from the canoes and the shore, we moored at the landing of the neat, soldierly, well kept camp.  The upper Aripuanan, a river of substantially the same volume as the Castanho, but broader at this point, and probably of less length, here joined the Castanho from the east, and the two together formed what the rubbermen called the lower Aripuanan.  The mouth of this was indicated, and sometimes named, on the maps, but only as a small and unimportant stream.