n overdrive, if one broke
out to measure.

The first blueskin student pilot ended a Calhoun-determined tour of duty
with rather more of respect for Calhoun than he'd had at the beginning.
The second was anxious to show up better than the first. Calhoun drilled
him in the use of brightness-charts, by which the changes in apparent
brightness of stars between overdrive hops could be correlated with
angular changes to give a three-dimensional picture of the nearer
heavens. It was a highly necessary art which had not been worked out on
Dara, and the prospective astrogators became absorbed in this and other
fine points of space-piloting. They'd done enough, in a few trips to
Orede, to realize that they needed to know more. Calhoun showed them.

Calhoun did not try to make things easy for them. He was hungry and
easily annoyed. It was sound training tactics to be severe, and to
phrase all suggestions as commands. He put the four young men in command
of the ship in turn, under his direction. He continued to use Weald as a
destination, but he set up problems in which the Med Ship came out of
overdrive pointing in an unknown direction and with a precessory motion.
He made the third of his students identify Weald in the celestial globe
containing hundreds of millions of stars, and get on course in overdrive
toward it. The fourth was suddenly required to compute the distance to
Weald from such data as he could get from observation, without reference
to any records.

By this time the first man was chafing to take a second turn. Calhoun
gave each of them a second gruelling lesson. He gave them, in fact, a
highly condensed but very sound course in the art of travel in space.
His young students took command in four-hour watches, with at least one
breakout from overdrive in each watch. He built up enthusiasm in them.
They ignored the discomfort of being hungry, though there had been no
reason for them to stint on food in Orede--in growing pride in what they
came to know.

When Weald was a first-magnitude star, the four were not highly
qualified astrogators, to be sure, but they were vastly better spacemen
than at the beginning. Inevitably, their attitude toward Calhoun was
respectful. He'd been irritable and right. To the young, the combination
is impressive.

Maril had served as passenger only. In theory she was to compare
Calhoun's lessons with his practise when alone. But he did nothing on
this journey which--teaching considere