“I am afraid a technical explanation would be too involved for you to understand. Briefly, a musical note produced on the crystal globe, is carried by ultra violet ray to the scene of the mine. The vibration will cause any unstable substance such as melinite to explode.”
“And you claim you actually can explode mines with this machine?” Penny asked.
“I not only claim it, I have demonstrated the machine’s powers,” Professor Bettenridge replied. “How I do it, of course, is my own secret.”
“Will you explode a mine for us now?” Louise questioned eagerly.
Professor Bettenridge looked mildly amused. “My dear young lady,” he said. “Do you realize that mines are very expensive? I have been able to obtain only a few, and naturally I must save them for official tests.”
“Of course,” stammered Louise. “I hadn’t thought of that.”
“Besides, the demonstrations have a certain element of danger,” the professor resumed. “I never give one without my assistant.”
Penny, who had been studying the machine with increasing interest, remarked that a story about it might make an interesting feature for the Star. To her surprise, the professor did not seem to favor the idea.
“You are employed by a newspaper?” he inquired.
“Yes, the Star.”