“No.  I can make nothing out,” he said at length, shaking his head.

“How strange!  I can distinguish the figure quite plainly.  But never mind, Mr. McKay; only do something.  Give him some help.  Try to save him.  Throw him a rope.”

McKay obediently seized a coil of rope, and, approaching the gunwale, said, quickly—­

“Only you must show me where to throw.”

“There, towards that mast; it’s coming close alongside.”

In her eagerness she had followed him, and was close behind as he gathered up the rope in a coil to cast it.

Once, twice, thrice, he whirled it round his head, then threw it with so vigorous an action that his body bent over and his balance was lost.

He might have regained it, but at this supreme moment a distinct and unmistakeable push in the back from his companion completed his discomfiture.

He clutched wildly at the shrouds with one hand—­the other still held the rope; but fruitlessly, and in an instant he fell down—­far down into the vortex of the seething, swirling sea.

“Ah, traitress!” he cried, as he sank, fully conscious, as it seemed, of the foul part she had played.

Had she really wished to drown him?  Her conduct after he had disappeared bore out this conclusion.

One hasty glance around satisfied her that McKay’s fall had been unobserved.  If she gave the alarm at once he might still be saved.

“Not yet!” she hissed between her teeth.  “In five minutes it will be too late to help him.  The waters have closed over him—­let him go down, to the very bottom of the sea.”

But she was wise in her fiendish wickedness, and knew that as they had been seen last together she must account for McKay’s disappearance.  At the end of an interval long enough to make rescue impossible she startled the whole yacht with her screams.

“Help!  Help!  Mr. McKay!  He has fallen overboard!”

They came rushing aft to where she stood once more holding on to the top of the companion, and plied her with questions.

“There! there! make haste!” she cried—­“for Heaven’s sake make haste!”

“A boat could hardly live in this sea,” said Captain Trejago, gravely.  “Still, we must make the attempt.  Who will go with me?” he asked, and volunteers soon sprang to his side.

It was a service of immense danger, but the boat was lowered, and for more than half-an-hour made such diligent search as was possible in the weather and in the sea.

After that time the boat was brought back to the yacht by its brave but disappointed crew.

“No chance for the poor chap,” said Captain Trejago, shaking his head despondingly in reply to Mrs. Wilders’s mute but eager appeal.

Soon afterwards they got up the anchor, and the yacht sped southward under a few rags of sail.

CHAPTER XIX.