t him to with a sharp
shock; he ran forward a few steps and found himself sinking. The roadway
immediately in front of him had doubtless been undermined by the action
of water; for the space of a dozen yards or more the pavement was but a
shell concealing an abyss.

Constans had already proceeded too far for retreat; he must go on or
founder where he stood. He flung himself forward, the oblong blocks of
granite, with which the street was paved, grinding together underneath
his feet as the mass yielded to the downward pressure. He was sucked in
to his knees, but instinctively he kept the upper part of his body
extended horizontally, his out-stretched hand seeking for some chance
holdfast. Then, as he was beginning to despair, he found it, a section
of small diameter lead piping that had been uncovered by the breaking
away of the surrounding earth. It bent under his clutch but did not give
way. With one last effort he pulled himself clear, gained the firm
ground beyond, and lay there trembling.

When afterwards he came to reason soberly over the adventure, the
conclusion seemed obvious that the pitfall had been a consequent upon
the breaking out of one of the ancient springs, so that the water, in
endeavoring to find an outlet, had finally undermined the whole
roadway. The chasm, as he looked back upon it, extended dear across the
street. Its depth was only conjectural, but the mass presented the
treacherous appearance of quaking sand, and Constans shuddered as he
gazed. Yet he had escaped; the peril was past; let him forget what was
behind and press forward.

Half a block farther on and he found himself in a cul-de-sac. The street
was filled from house-wall to house-wall with an immense mass of broken
stone, brick, and other debris. The cause was not far to seek.

Immediately upon the left rose one of the fabulously high buildings for
which the ancient city had been famous. It could not compare in
magnitude with the tremendous structures that he could discern still
farther ahead, but its dozen and a half of stories loomed up imposingly
when contrasted with the moderate sized houses adjoining it. Constans
looked up in wonder at its towering facade, then started back with an
exclamation of alarm.

It appeared that the foundations of the structure had in some way become
weakened, for the whole building had settled and was leaning over at a
terrifying divergence from the perpendicular. Being constructed of iron
truss-w