xygen, packed in the
space from which stores had been taken away. When the ship's air
supply was pumped past it, first moisture and then CO_{2} froze out.

Then the air flowed over the liquefied oxygen at a rate to replace the
CO_{2} with more useful breathing material. Then the moisture was
restored to the air as it warmed again. For so long as the oxygen
lasted, fresh air for any number of men could be kept purified and
breathable. The Med Ship's normal equipment could take care of no more
than ten. But with this it could journey to Weald with almost any
complement on board.

Maril stayed on Dara when the Med Ship left. Murgatroyd protested
shrilly when he discovered her about to be closed out by the closing
airlock.

"_Chee!_" he said indignantly. "_Chee! Chee!_"

"No," said Calhoun. "We'll be crowded enough anyhow. We'll see her
later."

He nodded to one of the first four student pilots, who crisply made
contact with the landing-grid office, and very efficiently supervised
as the grid took the ship up. The other three of the four
first-trained men explained every move to sub-classes assigned to
each. Calhoun moved about, listening and making certain that the
instruction was up to standard.

He felt queer, acting as the supervisor of an educational institution
in space. He did not like it. There were twenty-four men beside
himself crowded into the Med Ship's small interior. They got in each
other's way. They trampled on each other. There was always somebody
eating, and always somebody sleeping, and there was no need whatever
for the background tape to keep the ship from being intolerably
quiet. But the air system worked well enough, except once when the
reheating unit quit and the air inside the ship went down below
freezing before the trouble could be found and corrected.

The journey to Weald, this time, took seven days because of the
training program in effect. Calhoun bit his nails over the delay. But
it was necessary for each of the students to make his own line-ups on
Weald's sun, and compute distances, and for each of them to practise
maneuverings that would presently be called for. Calhoun hoped
desperately that preparations for active warfare did not move fast on
Weald.

He believed, however, that in the absence of direct news from Dara,
Wealdian officials would take the normal course of politicos. They had
proclaimed the ship from Orede an attack from Dara. Therefore, they
would specialize on de