I shall not weary you with an account of their exploration of all those trails. Suffice it to say that they soon exhausted the possibilities of the first three. Before noon they had demonstrated that the professor could have used none of them, save for a short distance, unless he possessed an airship, which they hardly believed possible, though more than once he had gone in theirs after bugs and other specimens.
But the first three trails, after straggling into the wilderness for a mile or so, became so overgrown with forest growth that it was evident they had not been used in a year or more. There was no use going along them.
The fourth was more promising, and showed plainly that the professor, or some one, had passed along it recently. The boys were quite sure it was Dr. Snodgrass, for the footprints showed the nail pattern of the shoes worn by the scientist. He was very particular about his tramping shoes, and always had them made to order.
“Though of course someone else might have his shoes made at the same place, and, naturally, the shoemaker would use the hob-nails in the same way,” observed Ned. “But I believe this was where the professor walked.”
The others were sure also, but the certainty did them little good, for they found where the person, whoever he was, had doubled back on his own trail.
“We’ll have to give this up,” said Jerry, “but it is getting more hopeful. Try the next one.”
This resulted in nothing. The trail was a blind one. But the one after that, which they started out on shortly after eating their lunch, at once raised new hope in their hearts. There were unmistakable signs that it had been traveled recently, and the peculiar marks of the hob-nailed shoes were very plain.
“We’ll find him!” cried Bob, enthusiastically.
But they were not destined to have matters so easy as they ventured to hope. The signs became more and more pronounced as they advanced, and there was no back-track.