"I should think it weighed most half a ton," grumbled Barlow.
"Never mind. We will soon have it in position. Quick! I hear the train!"
The rumbling of the train could be heard at a considerable distance. The two scoundrels didn't trouble themselves about the possible, or probable consequences of their dastardly plot. They only thought of revenging themselves upon the men who had ejected them from the train, and they felt, besides, an animosity against Robert and his miner friend.
They thought themselves without a witness, but in this they were mistaken. The boy already mentioned, whom they had pursued ineffectually, had followed them at a distance, having a feeling of curiosity about them.
"I wonder what they're up to?" he soliloquized, as he watched them tampering with the switch. He could not quite understand the meaning of their movements. But when they took the rock, and between them conveyed it to the railroad track, and put it in the way of the coming train, he understood.
"I believe the mean chaps want to wreck the train," he said to himself.
What should he do?
He bethought himself of calling out to them, and trying to prevent their plot. But he was sure they would pay no attention to him, and besides there was no time. He could already hear the thundering sound of the approaching train.
Tommy was on a bluff about fifteen feet above the roadbed. To descend the bank and run to meet the train would consume more time than he had at command.
"Oh, dear!" muttered Tommy. "There'll be a smash, and lots of people will be killed."