Walking rapidly, they arrived at the cabin quite breathless. As they tapped lightly on the door, Professor Bettenridge appeared visibly startled. He stiffened to alert, guarded attention, but relaxed slightly as his wife admitted the pair.
“Oh, it’s you two again,” he said none too pleasantly. “You are just in time to witness my final demonstration. We are waiting now for my assistant’s signal.”
“It seems to take a long while,” Mr. Johnson commented, glancing at his watch.
“Webb may have had trouble getting the mine overboard,” the professor soothed. “Besides, he has to move out of the danger zone.”
Penny and Salt looked at each other but said nothing. They were certain that Webb had been in no haste to return to shore.
“What are you two smirking about?” the professor demanded irritably. “I suppose you think my machine won’t work?”
“I’ll be surprised if it does,” Salt agreed, unruffled.
Mrs. Bettenridge, who stood at the window, suddenly cried: “There is the signal!”
Professor Bettenridge snapped on a switch and the ray machine began to hum. He turned on another motor and lights began to glow. Then he struck the crystal ball, producing a musical vibration.
Assuming a confident pose, he waited.