ate a quick lunch, then sat at the table
and talked about Candle's plans for opening the reluctant door. "The way I
figure it," Candle said, "I think that we can handle the whole thing by
radio. Which reminds me, one of these days I'm going to build a telescreen
that will transmit and receive through pseudo-met. Not too difficult really
if you approach the problem--"

"I better get Fromer for you," Hansen said hurriedly.

"Fromer here," said the bass voice.

"This is Candle. Let me talk to one of your so-called engineering
officers."

"Who the hell--"

"Shut up and go get 'em," Candle growled back. "And one more yelp out of
you and you'll stay in that ship till you rot."

There was a pause, then Fromer again, a meek Fromer. "My chief engineering
officer is with me."

"Okay. Now get this. Come to think of it, you'd better record it. Number
one: By now you know which component is a worm gear. You will notice, I'm
quite certain, that it engages a large notched wheel. The reason that the
door will not move is because at the point where the two gears meet, some
of the metal has oxidized. For possible use in future emergencies, I offer
this explanation. The entire mechanism is subject to periodic vacuum, when
the airlock door is operated. In between times, the mechanism is in the
ship's atmosphere. A condition of lower oxygen content thus obtains around
the sealed off area, and such an area is anodic--in other words, corrodible
with respect to the surrounding areas in which oxygen has free access. Now,
since this door has opened and closed successfully for about five hundred
years, it appears that there's a special reason why it suddenly refuses to
function. At a guess, you would experience this condition of intense
corrosion only when the aluminum in the wheel gear is exposed to something
like sodium hydroxide, and only at the point where it controls the worm
gear. Now, has this ship landed recently within such an atmosphere?"

"Three weeks ago on Ghortin IV," said the weak voice of the engineer. "We
landed to get some pictures of the cloud formations for souvenirs. We
dropped on the edge of a large body of water because the view was better--"

* * * * *

Candle shook his head sadly and said, "You could have avoided trouble
by coming in over the land instead of the water. The heat from the
ship boiled the water which undoubtedly contained sodium carbonate and
calcium hydroxide; prest