"I am sure I don't know, Sam. But this proves one thing."
"Exactly. See, here is an old coat and a pair of old shoes. Somebody has been in the habit of coming here--and he wasn't in the habit of getting in the way we got in."
They moved on, and soon reached a larger opening. Here they found a bit of old harness and, further on, where the ground was soft, the tracks of wagon wheels.
"Somebody has been in the habit of driving right in here!" exclaimed Tom. "We are sure to get out!" and his face showed his relief.
"Hark! what's that?" cried Sam, and shrank back as a strange rumbling was heard. "Is it an earthquake, or a landslide?"
"It's thunder, that's all," said Dick, a minute later, as they listened.
"To be sure--the storm was on us when we fell into the first hole," answered the youngest Rover.
"Perhaps we can be glad we are under shelter--if the storm is going to be a bad one," came from Tom. "But, come on, I want to see daylight again."
He moved on and then gave a cry of astonishment.
His brothers did so. On one side of the cave were piled thirty or forty packing cases. The majority of them were empty, but three, directed to one Jackson Dwight, Carwell, were full and nailed up.
"Well, I never!" murmured Sam. "Dick----"
"The freight thieves!" ejaculated the eldest Rover. "Don't you remember what was in the paper before we went south, and what was in again only yesterday? They have been missing freight from Carwell and Boxton and half a dozen other stations for over a year. The thieves must have brought their stuff here and then taken some of it from the packing cases and carted it away again."
"It certainly looks like it," answered Tom. "Only three full cases left. I wonder when these were taken?"
"Most likely only a short time ago," said Dick. "The cases look new."
"Do you suppose any of the freight thieves are around? If they are we want to keep out of their way--if they are desperate characters."
They moved on, and then Dick called a sudden halt.
"I can see daylight ahead," he said. "And somebody is moving around. Let us put out the torches."
His suggestion was speedily followed, and the three Rover boys advanced with caution. At its outer end the cave became broader while the roof was only about ten feet high.