the
utmost output of his thews was needed.

He had given up his original idea of mining a passage under the wall.
Indeed, this would have been a labor of weeks with the poor broken crock
which was his only tool, for the weight of the building above had turned
the earth to something very near akin to the hardness of stone. But he
had managed to scrape out a space underneath one brick, and found that
it was loosened, and with trouble could be dislodged; and so he was
burrowing away the earth from beneath others, to drop more bricks down
from their places, and so make a gangway through the solid wall itself.

But simple though this may be in theory, it was tediously difficult work
in practice. The bricks jammed even when they were undermined, and the
wall was four bricks thick to its further side. Moreover, every
alternate course was cross-pinned, and the workman was rapidly becoming
asphyxiated by the terrible reek which came billowing in from the
chamber beyond.

Still, with aching chest, and bleeding fingers, and smarting eyes,
Kettle worked doggedly on, and at last got a hole made completely
through. What lay in the blackness beyond he did not know; either Rad el
Moussa or the fireman might be waiting to give him a _coup de grace_ the
moment his head appeared; but he was ready to accept every risk. He felt
that if he stayed in the smoke of that burning camel's dung any longer
he would be strangled.

The hole in the brickwork was scarcely bigger than a fox-earth, but he
was a slightly built man, and with a hard struggle he managed to push
his way through. No one opposed him. He found and scraped his only
remaining match, and saw that he was in another bottle-shaped chamber
similar to the one he had left; but in this there was a doorway. There
was pungent smoke reek here also, and, though its slenderness came to
him as a blessed relief after what he had been enduring, he lusted
desperately for a taste of the pure air outside.

The door gave to his touch, and he found a stair. He ran up this and
stepped out into the corridor, where Rad had lured him to capture, and
then, walking cautiously by the wall so as not to step into any more
booby-traps, he came to the place where he calculated Murray would be
jailed. A large thick carpet had been spread over the door so as to
prevent any egress of the stinging smoke, or any ingress of air, and
this he pulled away, and lifted the trap.

There was no sound from below. "Great