As they finished their work the boys went with Ken to the laboratory. Professor Maddox looked up. "Hello, Fellows," he said. "Have you got your piece of machinery running?"
"Purring like a top," said Ken.
"Expected to run about as long," said Al.
"Have you finished any photomicrographs?" Ken asked. "Do they show anything?"
His father passed over a wet print. The boys gathered around it.
"It doesn't mean much to me," said Dave Whitaker. "Can you tell us what it shows?"
Ken's father took a pencil from his pocket and touched it lightly to a barely perceptible line across the center of the picture. "That is the boundary," he said, "between the cylinder wall and the piston taken from one of the samples you brought in."
"I can't see anything that looks like a line between two pieces of metal," said Ted Watkins. "It looks like one solid chunk to me."
"That is substantially what it is," said Professor Maddox. "There is no longer any real boundary as there would be between two ordinary pieces of metal. Molecules from each piece have flowed into the other, mixing just as two very viscous liquids would do. They have actually become one piece of metal."
He took up another photograph. "Here you can see that the same thing has happened in the case of the shaft and bearing samples we obtained from the Collin's Dam power plant. Molecules of the two separate pieces of metal have intermingled, becoming one single piece."