To the gunwales amidships two of the men fastened a couple of small crotched posts. In the forks was laid a pole, crosswise of the boat, and from this, by slender fiber cords, four slabs of wood were hung. Strolling down to the canoe, the travelers found that athwart its bottom had been laid a crosspiece supporting two shorter crotched posts, between which stretched another transverse pole; and from this pole in turn the lower ends of the four slabs had been suspended. Now the savages joined the tips of each pair of slabs by carved end sections, and the contrivance seemed to be complete--a sort of grate, its bars sloping at an angle of forty-five degrees. As the Americans eyed the arrangement in perplexity, one of the crew picked up from the bow of the canoe a pair of mallets the heads of which were wrapped in hide. With these he struck the slabs in rapid succession. Out rolled four notes of astonishing volume--the first four notes of the musical scale. Again and again he ran them over, then stopped. The deep tones thrummed away along the creek and died. "By George! a big xylophone!" Knowlton exclaimed, admiringly. "It sure talks right out loud," said Tim. "Lot o' class to these guys, at that. Bet this is their brass band, and we'll go rip-snortin' into the next town like we was on parade. Oughter have some flags to hang up in the boats, and mebbe a drum corps to help out. Wisht I had a tin whistle or somethin' and I'd join the orchester. I can toot a whistle fine." "My favorite instrument is the old-fashioned dinner horn," laughed Knowlton. "But I think you're wrong--this is some kind of signaling apparatus." "You have it right, senhor," Lourenço affirmed. "I have heard this sort of thing used, though I never before saw the instrument itself. Those notes will carry at least five miles, and the cannibals send messages by striking the bars in different order. This run which we have just heard is always used first, and no message is sent until a reply is received." "Bush telegraph," nodded McKay. "First call your operator and then shoot the message in code. Pretty ingenious for a bunch of absolute savages." Lourenço turned to Yuara and asked a question. Yuara curtly replied. "He says, Capitao, that this is to tell Monitaya we come. But we now are too far off for Monitaya's men to hear. The bars are made ready before starting so that they can be used as soon as we are within hearing. He says also that we start now." The Mayorunas already were entering their canoes. With cool deliberation the whites gathered up their equipment and settled themselves for the journey at whose end lay either life or death. The boat of Yuara started, and once more the flotilla was on its way. For an hour or more it swung on among the forested hills before the telegraph instrument was put to use. Then it paused, and the sonorous voice of the xylophone spoke to the jungle. A period of waiting brought no reply.