Signal in the Dark Part 17

"Come, come," said the professor, giving his wife a significant, warning glance. "There is no need for disagreement. The young ladies are quite welcome to search the car."

"We've already looked," Penny admitted. "The camera isn't there."

"Isn't it possible you were mistaken in the automobile?"

"I may have jotted down a wrong license number," Penny acknowledged reluctantly. "I'm sorry."

She turned to leave.

"That's quite all right," the professor a.s.sured her, his tone now becoming more friendly. "Do you girls live near here?"

"In Riverview," Louise supplied eagerly. "We drove over for a picnic.

Mrs. Leonard told us about your light ray machine!"

"Indeed." Professor Bettenridge looked none too pleased.

"She said you might be willing to show it to us."

"Mrs. Leonard displays a remarkable interest in our affairs," Mrs.

Bettenridge commented sarcastically.

Again her husband shot her a warning glance.

"My dear, it is only natural that she should be interested in such an amazing machine as ours," he said. "I see no reason why the young ladies should not view it."

"Oh, may we?" Louise cried eagerly.

Although his wife scowled with displeasure, the professor bade the girls follow him to the nearby shack. The door was padlocked and he opened it with a key.

Inside, the room was bare of furniture. There were a few boxes and a large table upon which rested a sizeable object covered with canvas.

"My secret ray machine is expected to revolutionize warfare," the professor said proudly. "Behold the product of fifteen years of faithful work!"

Dramatically he jerked aside the canvas cover, revealing a complicated mechanism of convex and concave mirrors which rotated on their bases. In the center of the machine was a small crystal ball.

"How does it operate?" Louise asked, deeply impressed.

"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 a.s.sistant."

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_."

"I must ask you to say nothing about this matter," the professor directed. "Under no circ.u.mstance could I permit a story to be written about my work."

"But why?"

"Publicity at this time might rob me of an opportunity to sell the machine. A very prominent man, James Johnson, is now considering its purchase."

"But I thought you were expecting to sell your invention to the government," Penny said, puzzled.

Professor Bettenridge bit his lip. Obviously, he was beginning to share his wife's annoyance at the girls.

"I regret I can't tell you all the details of my negotiations," he said.

"My wife and I are very tired, so if you will excuse us--"

"Certainly," said Penny, taking the hint. "Louise and I must be on our way to Riverview."

They started to leave, but before they could reach the door, someone tapped lightly on it. Professor Bettenridge and his wife exchanged a quick glance which Penny could not fathom. For a fleeting instant, she thought they both looked frightened.

Then the professor went to the door and opened it. A little man in a derby hat and with an apologetic manner stood on the threshold.

"Mr. Johnson!" exclaimed the professor, extending his hand. "My wife and I did not expect you until tomorrow."

"I came a little sooner than I planned," the newcomer admitted. "A business conference I had expected to attend was postponed until tomorrow. Naturally, that has upset my schedule. I had hoped you might consent to a demonstration of your machine tonight."

"Tonight?" The professor seemed caught off guard. "But that is impossible!"

"Impossible?" inquired Mr. Johnson. "Why?"

"For one thing, my a.s.sistant is not here."

"Can't you get in touch with him?"

"I doubt it. Besides, I have another engagement." The professor hesitated and added: "Officials of the Navy have invited me to confer with them tonight at the Gables Hotel in Riverview. I rather expect them to make me a very attractive offer for my invention."

"But you promised me first option on it!" Mr. Johnson protested. "If necessary, I can wait for the demonstration tomorrow night, though it will greatly inconvenience me."

"Tomorrow at eight o'clock," the professor nodded. "If you should care to put up a small sum of money as a guarantee of your intentions, I promise to make no final deal with the Navy until after that time."

"Why, yes," Mr. Johnson agreed, taking out his check book. "Any amount you say."

Feeling themselves no longer welcome by the Bettenridges, Penny and Louise slipped quietly away. As they climbed the hill they could hear the professor and Mr. Johnson discussing the amount to be paid.