"That is exactly what has been done," added Dick, soberly. "See, you can even notice where the slit extends further than the break. This was not as much an accident as we thought, Roger. Some rascal, who knew what we expected to do, tried to bring about our destruction in the rapids!" "But it must have been done since yesterday," declared the other angrily, "for we looked over every inch of the skin of the boat then, and surely would have noticed the deep scoring of a knife blade." "There can be no doubt about that," agreed Dick. "And the work was skillfully done in the bargain. Whoever made that cut expected that the boat would strike against rocks many times during the run of the rapids, and took chances that one of the blows would tear open the weak place. And that is what happened." "It would have gone much harder with us if we had not been most of the way down the descent," said Roger, with a frown on his face. "But, Dick, who could the treacherous rascal be? As far as we know, we have not made a single enemy among the members of the party. Would one of our Indian friends have played such a mean trick on us, do you think?" "No one but an enemy could have done it, Roger, because there was nothing to gain; for while some Indians might envy us our rifles these would surely be lost with us in the rapids and never recovered." "That makes the mystery worse than ever, then," fretted the other lad, who was so constituted that among his boy friends down along the Missouri he had often gone under the name of "Headstrong Roger." "I have a suspicion, although there is really nothing to back it up, that I can see," remarked Dick, reflectively, as though at some time in the past winter he had allowed himself to speculate concerning certain things which were now again taking possession of his mind. "Dick, tell me what it is about, please," urged his cousin, "because I'm groping in the dark, myself." "There is only one man that I know of who hates us bitterly," commenced Dick, and instantly a flash of intelligence overspread the face of the other. "Do you mean that French trader, François Lascelles?" he demanded. "I was thinking of him, and his equally unscrupulous son, Alexis," Dick admitted. "But, when we captured them last fall, they were held prisoners in the camp until Mayhew, the scout, was well on his way down the river and could not possibly be overtaken. Then the party of Frenchmen was let go, with the solemn warning from Captain Lewis that if any of them loitered around this region they would be shot on sight. And Dick, all winter long you remember we have seen nothing of Lascelles, or indeed for that matter any other white man."