“Hope I didn’t startle you folks,” said Bud, as he entered the room. “It was awfully stupid of me, but I forgot to wear my neutralizer wrist watch.”
“What! “Tom cried.
Bud looked at his friend in surprise. “Well, for Pete’s sake, don’t get so worked up about it. Anyone can make a mistake!”
“You don’t understand,” Tom said. “The alarm system didn’t go off this time!”
“Huh?” Bud stared. “You mean I didn’t set off the alarm, even though I wasn’t wearing the coil?”
“That’s right,” said Tom. “And the funny thing is, the alarm did go off about twenty minutes ago, but we couldn’t find anyone.”
“I think perhaps we’d better investigate further,” Mr. Swift said, rising.
DANGER SIGNAL 31
This time, Tom took a small wrench from his pocket and held it up close to the dial over the front door. The dial was supposed to react to the presence of metal and thus reveal any concealed weapons carried by visitors. But the fluctuating needle remained perfectly still.
“There’s your answer,” Tom announced grimly. “The whole alarm system is dead!”
CHAPTER 4
A PERILOUS EXPERIMENT
WHAT HAD WRECKED the alarm system? Tom wondered. Was it accidental, or a case of deliberate sabotage?
The young inventor ran downstairs to his laboratory workshop in the basement and came back a moment later with a kit of electrical tools. Then he began to make a complete inspection of the electromagnetic alarm circuits. In a few minutes he had the answer.
“It was sabotage, all right! Someone shorted the winding on this solenoid.
And in my opinion, it was done by a clever technician-someone who knew exactly what he was doing!”