“It’s not yet perfect,” he explained, “but I think it has great possibilities. With the unaided ear, one seldom spots a plane, by sound, more than six miles away. Even with my imperfect hearing, aided by my listening device, I have been able, more than once, to spot a plane coming from the sea ... American planes, of course ... at a distance of ten miles. Want to try it?” he asked.
“Of course,” was Betty’s instant reply. “Anything that helps us do our job well is just swell!”
“Well, now,” said Grandfather Norton, “this listening device of mine appears to work best on sounds rather close at hand, so we’ll just try it out on Joe Tratt. Just you put on these earphones, then I’ll turn on the electricity. Got a small electric plant in the furnace room, you know.”
“Joe Tratt—” Betty repeated. “What’s he going to do, stand off somewhere and shout?”
“No—No!” The old inventor’s voice cracked. “Joe always comes in from setting his nets out on the reef about this time. He’s coming in now, probably, only his boat’s motor doesn’t make a great deal of noise, so you don’t hear him with the unaided ear.
“Now—you ready?”
“Ready.”
He touched a button. A faint light appeared. He put his hand on a large metal horn and began turning it slowly.
“When you pick up the sound of a motor say, ‘Now’,” he shouted.
For ten seconds she listened intently. Then suddenly she said: