“Good. It will be flashing lightning bolts then, and we can see what luck we have. The last batch was a failure.” The man hurried out again. Mr. Parker touched Tom and Mr. Jenks on their shoulders.
“What is it?” asked Tom.
“I know the secret of making the diamonds,” said the scientist.
“What?” cried Mr. Jenks.
“It is by the awful power of the lightning bolts!” whispered Mr. Parker. “Everything is explained now—the reason why they make diamonds in this lonely place, near the top of the mountain. They need a place where the lightning is powerful. I can understand it now—I suspected it before. They make diamonds by lightning!”
“Are you sure?” cried Mr. Jenks.
“Positive.”
“I agree with you,” said Tom Swift. “I was just getting on that track myself, when I saw the electric wires running to the steel box. That explains the upright rod on the top of the mountain. The man says a storm is coming—very well; we'll stay here and watch them make diamonds!”
As he spoke there came the mutter of thunder, and the mountain vibrated slightly. The men in the cave redoubled their activity. Tom and his friends felt that the secret process they had so long sought was about to be demonstrated before their eyes.