Bob dropped his book and, leaping to his feet, strode to his chum's side.
"What is it?"
"Put on a headpiece, Bob," said Frank in a voice of great excitement. "I believe Jack is trying to get us."
Excited as his chum, Bob clamped a receiver on his head, while Frank manipulated the "amplifier" and "detector" knobs on the control apparatus.
A variety of sounds greeted the boys at first, whistles, calls, and chattering coming to their ears. Then as their tuner searched out the higher regions of the air, they shut out the sounds of the low-range air traffic. There was a thin, shrieking sound. Then, that also disappeared. And then quite suddenly the listening, expectant boys heard Jack's voice speaking to them just as plainly as if he stood in the room.
And then quite suddenly the listening expectant boys heard Jack's voice speaking to them just as plainly as if he stood in the room.
"Frank. Bob. Bob. Frank," Jack was saying. "Can you hear me? Can you hear me?"
"Hurray, Jack, sure we can hear you," cried Frank, bending forward to speak into the transmitter on the stand before him.
Then as Jack's voice continued calling without paying him any attention, he straightened up and laughed.