the static and
the arrival of the earth-tremor waves. The static and the appearance of
something from nowhere and the point of origin of the earth-shock
matched up. They were one event. The event was timed with the outburst
of radio noise, not the impact of the falling object, which was a minute
later.

* * * * *

Soames struggled to imagine what that event could be. The inter-base
radio babbled. Somebody discovered that the static had been on all
wave-lengths at the same time. Voices argued about it.

In the radar-dome Captain Moggs said indignantly:

"This is monstrous! I shall report this to Washington! What was that
thing, Mr. Soames?"

Soames shrugged.

"There isn't anything it could be," he told her. "It was impossible.
There couldn't be anything like that."

Gail cocked her head on one side.

"D'you mean it's something new to science?"

Soames realized how much he liked Gail. Too much. So he spoke with great
formality. The radar had tried to detect and range on something that
wasn't there. The nearest accurate statement would be that the radar had
detected something just before it became something the radar could
detect, which did not begin to make sense.

Planes didn't appear in mid-sky without previously having been somewhere
else; it wasn't a plane. There could be meteors, but it wasn't a meteor
because it went too slowly and changed course and stood still in the air
and went upward. Nor was it a missile. A ballistic missile couldn't
change course, a rocket-missile would show on the radar.

He looked at his watch.

"Six minutes and a half from the static," he said grimly. "Eighty miles.
Sound travels a mile every five seconds. Let's listen. Ten
seconds--eight--six--four--"

Now the wave-guide radar had gone back to normal operation. Its
silver-plated square tube flickered and quivered and spun quickly in
this direction and that, searching all the sky.

There was a booming sound. It was infinitely low-pitched. It was
long-continued. It was so low in frequency that it seemed more a
vibration of the air than a sound.

It died away.

"It's a concussion-wave," said Soames soberly. "It arrived four hundred
odd seconds after the static. Eighty miles.... A noise has to be pretty
loud to travel so far! A ground-shock has to be rather sharp to be felt
as an earth-tremor at eighty miles. Even a spark has to be very, very
fierce to mess up radio and radar reception at e