got to figure, but
type. Nobody hardly uses anything but sine waves for communication, but
I got to make this gadget turn out a freak wave-type by guess and golly.
I got a sort of test for it, though."

* * * * *

He straightened up and connected a cable from the generator to the Mark
IV communicator which was a factory twin of Betsy.

"I'm gonna feed this communicator half a micro-micro-watt of stuff like
the broadcast--I think," he announced grimly. "I saw the diagrams of the
transmitters they want us to make. I'm guessing the broadcast-wave they
use is close to it but not exact. Close, because it's bad for machines.
Not exact, because they're alive while they use it. I hope I don't hit
anything on the nose. Okay?"

Lecky said gently:

"I have never been more frightened. Go ahead!"

Sergeant Bellews depressed a stud. The communicator's screen lighted up
instantly. It was receiving the generator's minute output and accepted
it as a broadcast. But the signal was unmodulated, so there was no image
nor any sound.

* * * * *

The communicator's standby light flickered steadily.

Sergeant Bellews adjusted a knob on the generator. The communicator's
standby flicker changed in amplitude. Bellews turned the knob back. He
adjusted another control. The standby light wavered crazily.

Graves said nervously:

"I think I see. You are trying to make this communicator react as Betsy
did. When it does, you will consider that your generator is creating a
wave like the broadcasts from nowhere."

"Yeah," said Bellews. "It ain't scientific, but it's the best I can do."

He worked the generator-controls with infinite care. Once the
communicator's standby light approached sine-wave modulation. He hastily
shifted away from the settings which caused it. He muttered:

"Close!"

Then, suddenly, the communicator's lamp began to waver in an
extraordinary, hysterical fashion. Sergeant Bellews turned down the
volume swiftly. He wiped sweat off his forehead.

"I--I think I got the trick," he said heavily. "It's a hell of a
wave-type! Are you guys game to feed it into this communicator's output
amplifier?"

"I have six sets of cold chills running up and down my spine," said
Lecky. "I think you should proceed."

Howell said angrily:

"It's got to be tried, hasn't it?"

"It's got to be tried," acknowledged Sergeant Bellews.

He shifted the generator's cable from t