“Better fly low,” said Ned to Jerry, who was guiding the airship. “If you go up too high,” he went on, as they were approaching the location of the mysterious gorge, “they may see you.”
As far as they could learn by looking down and sweeping the landscape through powerful glasses, they were not seen, and the airship settled down at the entrance of the defile, to give the boys and the professor a chance to find the secret door before the cowboys arrived.
“We’ve got about three hours,” Jerry said. “It will take them that long to ride here.”
They entered the V-gorge, and when they came to the place where, always before, they had been stopped by the lack of the cattle signs, they examined the ground with new interest.
“Look at those splinters of wood!” exclaimed Ned. “That shows where the big stone-boat was pulled along over the stones, laden with cattle.”
“That’s right,” agreed Jerry. “Probably those splinters were there all the while.”
“It’s queer we didn’t notice ’em!” cried Ned. “I don’t believe they were as plain before. I’m sure we would have taken some notice of them if they had been. More likely they put more cattle on the wooden drag this time, so as to hurry them through the passage, and because of the greater weight more splinters were rubbed off.”
“That’s right,” agreed Jerry. “Anyhow, the thing is plain now, and if we follow the splinter trail to where it ends it ought to bring us right to the secret door. Where the splinters end there is the entrance.”
“That was my idea,” said Professor Snodgrass with a smile.