"Are you undertaking any new adventures, Tom?" asked Mary.
"Well, I'm thinking of going to Peru."
"Peru!" she cried. "Oh, what a long way to go! And when you get there will you write to me? I'm collecting stamps, and I haven't any from Peru."
"Is that—er—the only reason you want me to write?" asked Tom.
"No," said Mary softly, as she ran up the walk.
Tom smiled as he turned away.
Three days later he received a box from New York. It contained the samples from the Andes tunnel, and Tom at once began his experiments to discover a suitable explosive for rending the hard stone.
"It is compressed molten lava," said Mr. Swift. "You'll never get an explosive that will successfully blast that, Tom."
"We'll see," declared the young inventor.