nd they managed between
them to finish the supply, and then emptied the water pitcher forthwith,
as they were very thirsty.

"Now to hit upon a good way to stop up that villainous spy-hole," said
Harry, and looked around the cell for something which would answer the
purpose.

They could see nothing suitable until their eyes fell upon the
accumulation of dirt upon the window-ledge.

"Ah! I have it!" ejaculated Roger; and, climbing on Harry's shoulders,
he reached down a handful of the dust.

"Now mix this," he went on, "with that liquor left from the porridge.
That contains a good deal of sticky matter, and will make this stuff
hold together."

They mixed the dirt and dust and floury water all together, and, leaving
it for a time to harden slightly, found that the mass held fairly firmly
together, and might make a reasonably good plug.

"We must, however, wait for darkness, Roger," said Harry. "If we put
this in after dark it will not be noticed until the morning, by which
time it ought to have hardened sufficiently to prevent its being pushed
out again. If we were to do it now, it would be noticed when our friend
the spy comes round for a final look at us, and would doubtless be
removed again before it had had a chance of setting."

Darkness soon fell, and then the two silently and carefully pushed in
the already nearly solid plug of earth. They had sufficient to fill the
little opening completely, for they heard some of it patter down on to
the stone floor outside.

"There," said Harry, when they had finished, "if they do not find that
before morning, it should be hard, and then I doubt whether they will
trouble to bore it out again after it has set; but we shall see."

It was now perfectly dark in the cell, for even on the most brilliant
moonlight nights the light could not reach the cell, because of the high
walls all round the quadrangle outside, which prevented the rays from
streaming in.

Being exceedingly tired, and rather sleepy, the two friends spread their
jerkins on the block of stone forming the table, as it was far too damp
to lie on the floor, and were soon fast asleep in one another's arms.

They were awakened the next morning by the sound of the trap shutting
after the morning's supply of food had been put in; and their first
thought, before even glancing at the meal, was to see if the plug had
been disturbed. To their great joy, so far as they could tell, it had
not been touched; and,