bon dioxide fire extinguishers, which Smith and Jayjay
Kelvin used as jets.

Getting a fix on Pluto was easy enough; the lighthouse station at Styx
broadcast a strong beep sunward every ten seconds. They could also
pick up the radio lighthouses on Eros, Ceres, Luna, and Mimas.
Evidently, the one on Titan was behind the Jovian bulk.

They were ready to send their distress call.

"It's simple," Smith said as he opened the red panel in the wall of
the control room. "First we turn on the receiver." He pushed a button
marked _R_. "Then we turn these two wheels here until the pip on that
little screen is centered. That's the signal from Pluto. It comes in
strong every ten seconds, see?"

Jayjay watched with interest. He'd heard about screamers and had seen
them, but he'd never had the opportunity of observing one in action.

Like flares or bombs, they were intended for one-time use. The
instructions were printed plainly on the inside of the red door, and
Smith was simply reading off what was printed there.

"These wheels," he was saying, "line up the parabolic reflector with
the Pluto signal, you see. There. Now we've got it centered. Now, all
we have to do is make one small correction and we're all set. These
things are built so that they're fool-proof; a kid could operate it.
Watch."

Facing each other across a small gap were a pair of tapered screw
plugs, one male and one female. The male was an average of half an
inch in diameter; the female was larger and bored to fit the male.

"The female plug," Smith said, "leads to two tanks of high-pressure
gas inside this cabinet on the left. One tank of oxygen, one of
hydrogen. See how this male plug telescopes out to fit into the
female? All we have to do is thread them together, and everything is
automatic."

Jayjay was aware that Smith's explanations were meant to give Jeffry
Hull something to think about instead of his fears. Hull was basically
an Earth-hugger, and free fall did nothing to keep him calm. Evidently
his subconscious knew that he had to latch on to something to keep his
mental equilibrium, because he showed a tremendous amount of interest
in what should have been a routine operation.

"How do you mean, it's all automatic?" he asked. "What happens?"

"Well, you can't see into the female plug, but look here at the male.
See those concentric tubes leading into the interior of the cabinet on
the right? The outer one leads in the oxygen, the inner leads i