tone of voice in which the question was put and the gesture which
accompanied it were evidently quite intelligible, for Acor instantly
replied in deferential tones, at the same time pointing down the road;
and, sure enough, after the cavalcade had proceeded about two miles,
Inaguy and his companions were overtaken, trudging cheerfully along
under the escort of a man who both Dick and Earle remembered having seen
about the guard house earlier in the day.

The two friends, with their escort, reached the foot of the cliff road,
after a ride of some six miles, shortly after the sun had disappeared
behind the mountains at the western end of the valley. They were now in
the valley itself, with mountains hemming them in on every hand; and as
they gazed upward in wonder at the high, vertical cliffs all round them,
they realised at last that they were inside an absolutely impregnable
fortress, hewn out of the mountain range by the hand of Nature herself,
and accessible only by air, or by the road which they had just
traversed. After a thoroughly comprehensive survey of their
surroundings, Earle explained to Dick that the only theory upon which he
could account for so extraordinary a formation was, that thousands, or
possibly even millions, of years ago the valley had been the crater of a
gigantic volcano which, after the volcano had become extinct, had
gradually filled with debris, leaving a depression in the middle, which
in process of time, had become a lake. And, indeed, if the theory of a
volcano upon so gigantic a scale could but be accepted, it looked very
much as though Earle's explanation might be correct; for the soil of the
valley--a belt of flat land some two miles wide, extending all round the
lake--was light and friable, but extraordinarily rich, as is apt to be
the case with volcanic soil, while the vertical cliffs which hemmed it
in all round bore a striking resemblance to the interior of certain
well-known craters.

Just clear of the foot of the cliff road the party came upon an
encampment, easily recognisable as that of the body of soldiers seen
advancing from the city earlier in the day; and here the night was
spent, the two white men being housed in a capacious tent, most
luxuriously furnished and adorned, in which, shortly after their
arrival, a meal of so elaborate a description, that it might almost be
termed a banquet, was served to them by a staff of reverentially
obsequious servants, and in which the