But Captain Joe went back to the cub in a moment and lay down again. If there was any stranger around the boat, the dog certainly was not aware of the fact, the boys concluded. Yet some one had taken the cakes and the honey! Who could it have been, they asked each other.
“It wouldn’t be right for us to start on a river trip unaccompanied by a mystery,” laughed Clay. “We had a mystery with us while we were on the Amazon, and the Columbia panned out pretty well in that particular, too, so I’m not much astonished by the presence of a mysterious boarder now. He ought not to take the best of everything, though,” he added, with a grin at Case, who was still inconsolable because of the loss of the honey.
“Say,” Alex exclaimed, presently. “This is no joke! There’s something going on here that we ought to know more about. The pancakes and honey never walked off without legs! Some fierce creature may have come up out of the river and grabbed them, but I don’t believe it.”
“Do you think there’s some one hidden on the boat?” asked Case. “If there is, where is he? No place to hide here, that I know of.”
“I don’t know anything about that,” Alex returned. “No one from the shore took the two articles of food, for they were taken at points fifteen miles apart—unless we have been visited by two thieves using the same methods, which I do not believe.
“I’m going to find out whether human hands took the grub, or whether some monster came up out of the river and assessed us for a square meal. You boys stay here and watch in front, and I’ll climb on the little deck over the gasoline tanks and see what’s going on there. If anything I can’t handle shows up, I’ll call for help!”
Clay and Case sat for a long time with their eyes fixed on the open deck and the up-river landscape. They heard Alex scramble over the low cabin roof and take a position on the narrow space over the tanks. Then all was still save the rush of the water. Captain Joe arose again, sniffed at the port rail, peered over into the water, and gave a low growl.
“He sees something!” Clay cried, excitedly.
Case hastened to the rear window and looked out, as if to ask Alex a question. At first he only looked out. Then he leaned out. Then he dashed out of the cabin and called to Clay, a note of anxiety in his tone.
When Clay reached the deck he saw what had excited his chum. Alex was not on the narrow deck, not on the cabin roof, nowhere on the boat! The river ran away smooth and clear, sparkling in the light with no craft in sight. The boy had disappeared as utterly as if he had been dissolved in the hot air!