“The dangers are too great. Windows would be smashed for many miles around. Authorities would not permit such a test. Only with the greater difficulty did I obtain permission to discharge the mines under water.”
“I had not thought of that,” Mr. Johnson acknowledged. He hesitated, and it was evident that in another moment he would decide to purchase the machine without further tests.
“Mr. Johnson, I suppose you have witnessed tests made with your own mines,” Penny interposed. “Or have they all been made with those supplied by the professor?”
The remark infuriated Mr. and Mrs. Bettenridge, as she had expected it would.
“You and this young man are trying to discredit my machine!” he exclaimed wrathfully. “Please leave.”
“Why, certainly,” agreed Penny, but made no move to depart.
Seeds of suspicion already had been implanted in Mr. Johnson’s mind.
“The young lady is right,” he said. “I should request a test on a mine which I provide myself.”
“Ridiculous!” snapped the professor. “The machine will work equally well on any mine.”
“Then surely you should not object to one further test?”