At this moment the sound of the trumpets sounded even into the deepest recess of the cave.  Sirona started.  “That is the Roman tuba,” she exclaimed.  “I know the sound—­Phoebicius is coming this way.”

“He is doing his duty,” replied Paulus.  “And still, one thing more.  I saw last night a ring on your hand—­an onyx.”

“There it lies,” said Sirona; and she pointed to the farthest corner of the cave, where it lay on the dusty soil.

“Let it remain there,” Paulus begged of her; he bent over the senseless man once more to kiss his forehead, raised his hand towards Sirona in sign of blessing, and rushed out into the open air.

CHAPTER XIX.

Two paths led over the mountain from the oasis to the sea; both followed deep and stony gorges, one of which was named the “short cut,” because the traveller reached his destination more quickly by that road than by following the better road in the other ravine, which was practicable for beasts of burden.  Half-way up the height the “short cut” opened out on a little plateau, whose western side was shut in by a high mass of rock with steep and precipitous flanks.  At the top of this rock stood a tower built of rough blocks, in which the anchorites were wont to take refuge when they were threatened with a descent of their foes.

The position of this castle—­as the penitents proudly styled their tower—­was well-chosen, for from its summit they commanded not only the “short cut” to the oasis, but also the narrow shell-strewn strip of desert which divided the western declivity of the Holy Mountain from the shore, the blue-green waters of the sea, and the distant chain of hills on the African coast.

Whatever approached the tower, whether from afar or from the neighborhood, was at once espied by them, and the side of the rock which was turned to the roadway was so precipitous and smooth that it remained inaccessible even to the natives of the desert, who, with their naked feet and sinewy arms, could climb points which even the wild goat and the jackal made a circuit to avoid.  It was more accessible from the other side, and in order to secure that, a very strong wall had been built, which enclosed the level on which the castle stood in the form of a horseshoe, of which the ends abutted on the declivity of the short road.  This structure was so roughly and inartistically heaped together that it looked as if formed by nature rather than by the hand of man.  The rough and unfinished appearance of this wall-like heap of stones was heightened by the quantity of large and small pieces of granite which were piled on the top of it, and which had been collected by the anchorites, in case of an incursion, to roll and hurl down on the invading robbers.  A cistern had been dug out of the rocky soil of the plateau which the wall enclosed, and care was taken to keep it constantly filled with water.