s
and isn't a comet any longer."

* * * * *

At this instant, which was 04 hours 25 minutes ship time, the alarm-bell
rang. It clanged stridently over Baird's head, repeater-gongs sounded all
through the ship, and there was a scurrying and a closing of doors. The
alarm gong could mean only one thing. It made one's breath come faster or
one's hair stand on end, according to temperament.

The skipper's face appeared on the direct-line screen from the navigation
room.

"_Plumies?_" he demanded harshly. "_Mr. Baird! Plumies?_"

Baird's hands were already flipping switches and plugging the radar room
apparatus into a new setup.

"There's a contact, sir," he said curtly. "No. There was a contact. It's
broken now. Something detected us. We picked up a radar pulse. One."

The word "one" meant much. A radar system that could get adequate
information from a single pulse was not the work of amateurs. It was the
product of a very highly developed technology. Setting all equipment to
full-globular scanning, Baird felt a certain crawling sensation at the
back of his neck. He'd been mapping within a narrow range above and below
the line of this system's ecliptic. A lot could have happened outside the
area he'd had under long-distance scanning.

But seconds passed. They seemed like years. The all-globe scanning
covered every direction out from the _Niccola_. Nothing appeared which
had not been reported before. The gas-giant planet far behind, and the
only inner one on this side of the sun, would return their pulses only
after minutes. Meanwhile the radars reported very faintfully, but they
only repeated previous reports.

"No new object within half a million miles," said Baird, after a suitable
interval. Presently he added: "Nothing new within three-quarter million
miles." Then: "Nothing new within a million miles ..."

The skipper said bitingly:

"_Then you'd better check on objects that are not new!_" He turned aside,
and his voice came more faintly as he spoke into another microphone.
"_Mr. Taine! Arm all rockets and have your tube crews stand by in combat
readiness! Engine room! Prepare drive for emergency maneuvers!
Damage-control parties, put on pressure suits and take combat posts with
equipment!_" His voice rose again in volume. "_Mr. Baird! How about
observed objects?_"

Diane murmured. Baird said briefly:

"Only one suspicious object, sir--and that shouldn't be suspicious. We
ar