terribly and unhappily misdirected. In other words a sheer waste of time and energy."

Joan and Peter unclinched and faced Hedgerly. "We like it," they said in chorus.

Hedgerly nodded understandingly. "But Marie Baker wouldn't."

"Let's go out, Peter," pleaded the girl earnestly. "This unwelcome bird makes me feel like a female homewrecker!"

Hedgerly beamed. "Do go," he said. "And enjoy yourselves until I can locate Peter's future wife—my grandmother."

The big machine should have been quiet according to theory. It had no moving mechanical parts to hum or gears to clash nor levers to chatter. It had for its moving-member a magnetic field that varied on a pure sine wave of intensity from a terrific flux-density in one direction, through zero, and thence to an equally terrific flux-density in the opposite polarity. At one newspaper interview as the machine was being built some reporter had erroneously noted that the magnetic field strength at maximum was strong enough to affect the iron in your blood. This was intended for sheer hyperbole, but the fact remained that the magnetic field between the big pole pieces was strong enough to warp the path of light. Well, the shift could be measured with the most delicate of optical instruments.

Theoretically, a varying magnetic field should not make a sound.

Actually, it did. The field at maximum was strong enough to cause deep magnetostriction of the magnetic metals of the machine. They vibrated in sympathy with the varying field: their dimensions changing enough to set up sound waves in the air of the room.

So the theoretically silent machine actually made a clear humming roar that shattered the eardrums and seemed to press offensively on the skulls of those working within the chamber.

Even Peter Hedgerly found it oppressing after an hour or two, and he of all men should have been used to it.

He removed his eye from the observing telescope and blinked to relieve the strain. He looked up at Joan, nodded affably, and his right hand snapped the main switch.

The terrible humming roar died. "Hello," he said brightly. "What brings you here?"

Joan Willson laughed sourly. She handed Peter a newspaper. Peter bent his head to read:

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