and higher; presently it rose
above the top of the loophole, and Rupert now watched anxiously how
fast it ran. Floating on his back, and keeping a finger at the
water level against the wall, he could feel that the water still
rose. It seemed to him that the rise was slower and slower, and at
last his finger remained against a point in the stones for some
minutes without moving. The rise of the water inside the dungeon
had ceased.

That it continued outside he guessed by a slight but distinct
feeling of pressure in the air, showing that the column of water
outside was compressing it. He had no fear of any bad consequences
from this source, as even a height of twelve feet of water outside
would not give any unbearable pressure. He was more afraid that he
himself would exhaust the air, but he believed that there would be
sufficient; and as he knew that the less he exerted himself the
less air he required, he floated quietly on his back, with his feet
resting on the bar across the loophole, now two feet under water.

He scarcely felt the water cold. The rain had come from a warm
quarter; and the temperature of the water was actually higher than
that of the cold and humid dungeon.

Hour after hour passed. The night appeared interminable. From time
to time Rupert dived so as to look through the loophole, and at
last was rewarded by seeing a faint dull light. Day was beginning;
and Rupert had no doubt that with early morning the sluices would
be opened, and the moat entirely cleared of water.

He had, when talking with his gaoler one day, asked him how they
got rid of the water in the dungeon after a flood, and the man said
that there were pipes from the floor of each dungeon into the moat.
At ordinary times these pipes were closed by wooden plugs, as the
water outside was far above the floor; but that after a flood the
water was entirely let out of the moat, and the plugs removed from
the pipes, which thus emptied the dungeons.

From the way in which the fellow described the various
arrangements, Rupert had little doubt that the sluice gates were at
times purposely left closed, in order to clear off troublesome
prisoners who might otherwise have remained a care and expense to
the state for years to come.

Long as the night had seemed, it seemed even longer before Rupert
felt that the water was sinking. He knew that after the upper
sluice had opened the fosse might take some time to fall to the
level of the water insi