Signal in the Dark Part 28

"Probably to give Webb time enough to work on the mine or exchange them,"

Penny said, and then frowned thoughtfully. "But what if the machine actually should work? After all, the professor agreed to explode Mr.

Johnson's mine, and apparently he's marked it with his initials. It won't be easy to subst.i.tute another one now."

"All the same, if I'm any good at guessing, it will be done. Now what shall we do until nine o'clock? Grab ourselves something to eat?"

Penny was about to suggest that they drive to a village cafe, when she noticed Webb returning alone from up the beach. Barely did the pair have time to duck out of sight behind a boulder before he approached.

Walking directly to the shack, he unlocked the door, and entered.

"Now this must be where the hocus-pocus begins!" Salt whispered. "We've got to find out what he does to that mine."

"Louise and I climbed up in that tree the other day and looked through the gla.s.s in the top."

"Then that's the trick for us! Come on!"

Making no sound, the pair climbed the tree close beside the shack.

Noiselessly, they inched their way toward the skylight, and lying flat, peered down into the dark interior.

Webb had lighted a lantern which he hung on a wall nail. Unaware that he was being watched, he squatted in front of the mine which bore Mr.

Johnson's initials, studying it thoughtfully.

Muttering to himself, he next took a powerful ratchet drill, and for a long time worked with it on the mine, boring a tiny but deep hole.

"I'm getting stiff in this position," Penny whispered. "What is he doing, Salt?"

"Don't know," the photographer admitted, puzzled. "Apparently, he's doctoring Mr. Johnson's mine so it will explode tonight, but I'm not smart enough to figure how the trick will be accomplished."

By now it was so dark that the pair in the tree no longer feared they would be seen. Keeping perfectly still, they watched the work in the room below.

"It's clear why Professor Bettenridge set nine o'clock for the demonstration," Salt whispered. "Webb needed all this time to get the mine ready."

"And that's why they brought it here instead of dumping it into the lake," Penny added. "But how can they make the mine explode at exactly the right moment?"

After Webb had worked for a while longer, he arose and stretched his cramped muscles. Going to a cupboard, he removed a white powder from a gla.s.s tube, and carefully inserted it in the hole he had just made in the mine. As a final act, he sealed the tiny hole with another material, and polished the surface so that the place did not show.

"Slick work!" Salt commented. "By the time he's through, no one ever could tell the mine has been touched! Certainly not that thick-skulled Johnson."

Apparently satisfied with his work, Webb put away his tools, made a final inspection of the mine, and then left the shack. After carefully locking the door, he disappeared into the night.

"Now what's our move?" Penny asked as she and Salt finally slid down from their uncomfortable perch. "Shall we tell Mr. Johnson what we just saw?"

"We could, but he might not believe us. Penny, I have a better idea! If we can get inside the shack--"

"But it's locked!"

"The skylight may be open." Salt climbed up on the roof to investigate, but to his disappointment, the roof window was tightly fastened from inside.

"We could smash the gla.s.s," Penny suggested dubiously.

Salt shook his head. "That would give the whole thing away. No, I think we can get inside another way, but we'll have to work fast! Now that Webb has the mine ready for the demonstration, the professor and Mr. Johnson may show up here at any minute."

CHAPTER 19 _THE LANTERN SIGNAL_

Salt explained that he intended to pick the lock of the shack door.

"When I worked the police beat, a detective taught me this trick," he explained. "You keep watch while I work."

Now that Webb had disappeared no one was to be seen near the beach. To Penny's relief, not a person appeared, and Salt, working swiftly, soon had the door open.

To make certain they would not be taken unawares, Salt relocked the door on the inside. Groping about, he found the lantern Webb had left behind, and lighted it.

Three mines lay on the floor. "Which is the right one?" Penny asked.

"They all look alike!"

"Mr. Johnson's initials must be on the one Webb tampered with."

Salt turned over one of the mines, inspecting it.

"That thing might go off any minute," Penny said, edging away. "Do be careful, Salt."

Salt chuckled. "If it should go off, we'd never know what hit us," he said. "This is the one Webb tampered with all right. Penny, how are you at forging?"

"Forging?" she repeated, not understanding what he meant.

"Can you duplicate Mr. Johnson's initials on another mine?"

"Oh, I don't think so. Not so it would look the same."

"Sure, you can," Salt said, thrusting his pocket knife into her hand. "It will be dark and no one will look too carefully."

"But why do you want me to do it? You mean to subst.i.tute Mr. Johnson's mine for one of the others?"

"That's the ticket," chuckled the photographer. "Maybe my guess is wrong, but I have a sneaking suspicion if we use one of the professor's own mines, it will fail to explode."

"The mine has to be doctored with that powder we saw Webb use!"

"That's my theory, Penny."

"But maybe the other mines have already been treated."

"That's a possibility," Salt admitted thoughtfully. "No way of telling that, because the hole would be covered so skillfully. We'll have to take a chance on it."

While Salt held the lantern, Penny scratched Mr. Johnson's initials on the metal covering of the mine. Skilled in art, she was able to copy them fairly well.