the blood-red sun was sinking beyond the distant geral mountains, when a canoe, containing four white men and three natives, came to a halt a thousand miles from the mighty amazon, in the upper waters of the xingu river, near the great table-land of matto grosso.

it was hard work, forcing the long shallow boat against the rapid current of the stream, whose unknown source is somewhere among the famous diamond regions of brazil. it was plain sailing for three hundred leagues from the amazon, from whose majestic volume the little party of explorers had turned southward more than a month before. the broad sail, which was erected in the centre of the craft, swept it smoothly along over the narrowing bosom of the xingu, between luxuriant forests and past tribes of strange-looking indians, who stood on the banks staring wonderingly at the extraordinary beings, the like of which many of them had never seen before.

occasionally the explorers put ashore, and, using only the language of signs, exchanged some of the beads and gaudy trinkets for the curious articles of the savages. endless varieties of fruit were so abundant that it was to be had for the simple trouble of plucking; while the timid natives stood in such awe of their visitors, that the thought of harming them never entered their minds.

but ominous changes were gradually noted by our friends, as they steadily ascended the mysterious stream. at first the natives fled at their approach, and failed to understand the signs of comity, or were so distrustful of the strangers that they refused to meet their advances. fleeing into the woods or high hills, they peeped out from their coverts, uttering strange cries and indulging in grotesque gestures, the meaning of which could hardly be mistaken. had there been any misapprehension on the part of the visitors, there was none after several scores launched their arrows at the boat, as it glided away from the shore and up stream. the aim was wild and no one was struck, but when professor ernest grimcke, the sturdy, blue-eyed scientist of the party, picked up one of the missiles and carefully examined it, he made the disturbing announcement that it was tipped with one of the deadliest of known poisons.

the other members of this exploring party were fred ashman, a bright, intelligent american, four-and-twenty years of age; jared long, an attenuated, muscular new englander in middle life, and aaron johnston, a grim, reserved but powerful sailor from new bedford, who had spent most of his life on whaling voyages. professor grimcke and ashman were joint partners in the exploring enterprise, long and johnston being their assistants.

in addition, there were three native servants, or helpers, known as bippo, pedros and quincal. they had been engaged at macapa, near the mouth of the amazon. they were rather small of size, the first-named being the most intelligent, and in that warm, tropical climate wore no clothing except a strip of native cloth around the loins. ashman had striven to teach them the use of firearms, but they could never overcome the terror caused by the jet of fire and the thunderous explosion when the things were discharged. they, therefore, clung to their spears, which, having honest points, cannot be said to have been very formidable weapons in their hands, even though each native was able to throw them with remarkable deftness and accuracy.

the sail that had served the explorers so well, where the xingu was broader and with a slower current, became useless, or at least proved unequal to the task of overcoming the force of the stream. consequently they had recourse to the broad-bladed oars, with which they drove the canoe swiftly against the resisting river, cheered by the oft-repeated declaration of the professor, whose spirits never flagged, that the harder it proved going up stream, the easier must it be in descending, and that the arrangement was much better than if the condition of affairs were reversed.

the most tiresome work came when they reached some place, where the falls or rapids compelled them to land, and, lifting the boat and its contents from the ground, carry it round the obstruction to the more favorable current above. these portages varied in length from a few rods to a fourth of a mile, and the further the party advanced, the more frequent did they become.

"we have gone far enough for to-night," said the professor, as the prow of the boat was turned toward the left bank; "we will go into camp and make ready for to-morrow."

a few minutes later, the bow of the canoe gently touched the dark sand of the shore. bippo, pedros and quincal understood their duty so well that, without suggestion from the others, they leaped into the shallow waters, ran a few steps, and, grasping the front of the craft, drew it so far upon the land that the others stepped out without so much as wetting the soles of their shoes.

this task was no more than finished, when the natives scattered in the forest, which came almost to the edge of the water, in quest of fuel. this of course was so abundant that the work was slight, but since professor grimcke and fred ashman paid them well for their services they were left to attend to that duty unassisted.

as the surroundings of the party were entirely new and strange, grimcke proposed that while the evening meal was being prepared, they should find out, if it could be done, whether any unwelcome neighbors were likely to disturb them before morning. after a brief consultation, it was decided that the professor and jared long should make their way up the river, keeping close to shore, with the purpose of learning the extent of the rapids, while ashman and the sailor, johnston, should follow the clearly marked trail which led directly away from the stream and into the forest. it was more than probable that one of the couples would come upon something worth knowing, and it was not unlikely that both would return with important information.

twilight is of short duration in the low latitudes, and the wish of the four white men was to be back in camp at the end of an hour, by which time night would be fairly upon them. but the moon was at its full and would serve them better than the twilight itself.

the german and new englander, therefore, moved away from camp, following the course of the xingu, while their two friends quickly vanished in the forest. each carried his repeating winchester and his smith & wesson.

ashman felt some misgiving because of the trail leading into the woods from a point so near the camp. it seemed likely to have been worn by the inhabitants of some village near at hand, though it was possible that the innumerable feet of wild animals on their way to and from the river may have been the cause. the upper waters of the xingu are remarkably clear and pure, a fact which rendered the first theory most probable.

the explorers had landed in a dangerous region, as they were destined to learn very soon, and the experience of the couples who took routes at right angles to each other was of the most thrilling character.

it has been stated that the progress of the canoe had been checked, as was often the case before, by the rapids of the xingu, which could be passed only by carrying the canoe and luggage to the smoother waters above. it was apparent that the river frequently overflowed its banks, for immense quantities of driftwood lined both shores, while the vegetation had been swept away to that extent that a space of a dozen feet from the margin of the stream was comparatively free from it. thus both parties found the travelling easy.

the rapids were a hundred yards wide, more or less, and, with such a steep incline, that the foamy waves dashed hither and thither and against each other with the utmost fury, sending the spray high in air and sweeping forward with such impetuosity that it seemed impossible for the strongest craft under the most skilful guidance to shoot them. the explorers studied them with great interest as they ascended the left bank.

it was inevitable that in a country with such excessive vegetable growth, every part of the xingu should show much floating timber. the logs which plunged through the rapids played all manner of antics. sometimes they leaped high out of the waters, like immense sea monsters, the out-spreading limbs showing a startling resemblance to the arms of a drowning person mutely appealing for help. then a heavy trunk would strike a rock just below the surface, and the branches, dripping with spray, swept over in a huge semi-circle. the roar and swirl suggested the whirlpool below the falls of niagara, one of the most appalling sights in all nature.