n fastened the locking bar, bringing out of the
long-motionless metal another protesting screech, Dalgard had a chance
to look about him. They were in a room some eight or nine feet long,
the violet light showing up well tangles of equipment hanging from
pegs on the walls, a pile of small cylinders on the floor. At the far
end of the chamber was another hatch door, locked with the same type
of bar as Sssuri had just lowered to seal the inner one. The merman
nodded to it.

"The sea--"

Dalgard slid his knife back into its sheath. So the sea lay beyond. He
did not welcome the thought of passing through that door. Like all of
his race he could swim--perhaps his feats in the water would have
astonished the men of the planet from which his tribe had emigrated.
But unlike the mermen, he was not sea-born, nor equipped by nature
with a secondary breathing apparatus to make him as free in the world
of water as he was on land. Sssuri might crawl through that hatch
without fear. For Dalgard it was as big a test as to turn and face
what now raged in the corridor on the inner side.

"There is no hope that they will go now," Sssuri answered his vague
question. "They are stubborn. And hours--or even days--will mean
nothing. Also they can leave a guard there and rove at will, to return
upon signal. That is their way."

This left only the sea door. Sssuri padded across the chamber and
reached up to free one of the strange objects dangling from the wall
pegs. Like all things made of the marvelous substance used by Those
Others for any article which might be exposed to the elements, it
seemed as perfect as on the day it had first been hung there, though
that date might be a hundred or more Astran years earlier. The merman
uncoiled a length of thin, flexible piping which joined a two-foot
canister with a flat piece of metallic fabric.

"Those Others could not breathe under the water, as you cannot," he
explained as he worked deftly and swiftly. "Within my own memory we
have trapped their scouts wearing aids such as these so that they
might spy upon our safe places. But their last foray was some years
ago and at that time we taught them such a lesson that they have not
dared to return. Since they are not unlike you in body and since you
breathe the same air aboveground, there is no reason why this should
not take you out of here."

Dalgard accepted the apparatus. A couple of elastic metal bands
fastened the canister to the chest of