It was now nearly noon, and the captain looked around for Ralph, but did not see him.  He went to search for him, and finding that the boy had not passed Maka, who was on watch, he concluded he must have gone to the lake.  There was no reason why the restless youth should not seek to enliven his captivity by change of scene, but Captain Horn felt unwilling to have any one in his charge out of sight for any length of time, so he went to look for Ralph.

He found no one on the rocky shelf.  As there had been little reason to expect a water attack at this hour, Mok had been relieved from guard for a meal and a nap.  But as Ralph was not here, where could he be?  A second glance, however, showed the captain the boy’s clothes lying close by, against the upright side of the rock, and at that moment he heard a cry.  His eyes flashed out toward the sound.  There on the other side of the water, sitting on a bit of projecting rock not far from the great opening in the cave, he saw Ralph.  At first the captain stood dumb with amazement, and he was just about to call out, when Ralph shouted again.

“I swam over,” he said, “but I can’t get back.  I’ve got the cramps.  Can’t you make some sort of a raft, and come over to me!  The water’s awfully cold.”

Raft, indeed!  There was no material or time for anything of the kind.  If the boy dropped off that bit of rock, he would be drowned, and the captain did not hesitate a moment.  Throwing aside his jacket and slipping off his shoes, he let himself down into the water and struck out in Ralph’s direction.  The water was, indeed, very cold, but the captain was a strong swimmer, and it would not take him very long to cross the lake at this point, where its width was not much more than a hundred feet.  As he neared the other side he did not make immediately for Ralph.  He thought it would be wise to rest a little before attempting to take the boy back, and so he made for another point of rock, a little nearer the opening, urging the boy, as he neared him, to sit firmly and keep up a good heart.

“All right,” said Ralph.  “I see what you are after.  That is a better place than this, and if you land there I think I can scramble over to you.”

“Don’t move,” said the captain.  “Sit where you are until I tell you what to do.”

The captain had not made more than two or three strokes after speaking when his right hand struck against something hard, just below the surface of the water.  He involuntarily grasped it.  It was immovable, and it felt like a tree, a few inches in diameter, standing perpendicularly in the lake.  Wondering what this could be, he took hold of it with his other hand, and finding that it supported him, he let his feet drop, when, to his surprise, he found that they rested on something with a rounded surface, and the idea instantly came into his mind that it was a submerged tree, the trunk lying horizontally, from which this upright branch projected.  This might be as good