McCarty was waiting for him at the machine. "Now the first lesson is going to be a dirty one," he said. "We will have to crawl under the car, so you can see how each part works."
Shedding their coats, the two wriggled under on the wet ground and, lying on their backs, McCarty pointed out the various cog-wheels that worked the car and the swinging table.
"Gosh!" exclaimed McCarty suddenly. "Look at that!"
Startled, Walter looked to where the other was pointing. In one of the deep, sharp niches, into which the long teeth of the ratching descended when the platform was in motion, was wedged a round, yellow stick, of some eight inches in length.
McCarty pulled out the strange object and looked at it musingly. He broke off a bit of it, and, crumbling it up in his hand, examined it closely. "That stuff must have been put in there just before I went on duty night before last," he said. "Gosh! It's lucky the nigger struck on me before I started up the machine."
"Why?" Walter asked. "What is that stuff, anyway?"
McCarty threw him the stick. "Catch it," he said; "that's dynamite of the strongest grade."
Walter held the stick gingerly, as though he was afraid it might go off at any minute.
"Don't be afraid of it," laughed McCarty. "It doesn't go off so very easy. It needs a sudden, hard jar, or a cap and fuse, to explode it. If I had swung that thirty-ton platform around on top of that stuff the machine would likely have been pretty badly smashed up, and maybe some of us killed."
"Who could have put it there?" Walter asked.