Spring had lingered far into summer where they were, and the foliage was not yet touched by heat. All the forest was in deep and heavy green, hiding every object a hundred yards away, but from their opening they saw a blue and speckless sky, which the three by and by watched attentively, and with the same motive. Before the dark had begun to come in the east they saw a thin dark line drawn slowly across it, the trail of smoke. It might not have been noticed by eyes less keen, but they understood at once that it was a signal. Robert noted its drifting progress across the heavens, and then he said to Willet: "How far from here do you calculate the base of that smoke is, Dave?" "A long distance, Robert. Several miles maybe. The fire, I've no doubt, was kindled on top of a hill. It may be French speaking to Indians, or Indians talking to Indians." "And you don't think it's people of ours?" "I'm sure it isn't. We've no hunters or runners in these parts, except ourselves." "And it's not Tandakora," said the Onondaga. "He must be much farther away." "But the signal may be intended for him," said the hunter. "It may be carried to him by relays of smoke. I wish I could read that trail across the sky." "It's thinning out fast," said Robert. "You can hardly see it! and now it's gone entirely!" But the hunter continued to look thoughtfully at the sky, where the smoke had been. He never underrated the activity of the French, and he believed that a movement of importance, something the nature of which they should discover was at hand. "Lads," he said, "I expected an easy night of good sleep for all three of us, but I'm thinking instead that we'd better take to the trail, and travel toward the place where that smoke was started." "It's what scouts would do," said Tayoga tersely. "And such we claim to be," said Robert. As the sun began to sink they saw far in the west another smoke, that would have been invisible had it not been outlined against a fiery red sky, across which it lay like a dark thread. It was gone in a few moments, and then the dusk began to come. "An answer to the first signal," said Tayoga. "It is very likely that a strong force is gathering. Perhaps Tandakora has come back and is planning a blow." "It can't be possible that they're aiming it at us," said the hunter, thoughtfully. "They don't know of our presence here, and if they did we've too small a party for such big preparations." "Perhaps a troop of Pennsylvanians are marching westward," said Tayoga, "and the French and their allies are laying a trap for them." "Then," said Robert, "there is but one thing for us to do. We must warn our friends and save them from the snare." "Of course," said Willet, "but we don't know where they are, and meanwhile we'd better wait an hour or two. Perhaps something will happen that will help us to locate them."