But was it an echo?

The sound had scarcely died away when it was repeated again.  A moment later Jervis heard it yet again, and knew for a certainty that it was no echo, but someone whistling back to him.

The breeze had freshened to a gale that roared in his ears like thunder, as he drew his boat high up beyond reach of the tide that was running in strongly; and when the boat was safe he set out to climb the rocks.  Up, and up, a dizzy height he went, finding foothold with difficulty, for what looked like solid rock had a trick of crumbling when stepped upon, just as if it were rotten mortar.

But he reached the top at last, and paused to look about him, holding fast with both hands, for the force of the wind at this height was so great that he feared lest he should be blown away.

On one side was the bay, with great waves, foam-crested, rolling in, to break with a thunderous roar on the beach.  Spread out on the other hand was the wild, rocky waste, full of dangers now, for in the deep valleys between great rock boulders the incoming tide was rising and making deep pools where a little before had been dry ground.

It was these pools that Jervis feared.  If Mary had slipped into one of these deep places she might easily be caught by the rising flood, and drowned before help could reach her.

The mere thought turned him sick, and he whistled shrilly as before.

The answering whistle came so promptly, and sounded so close, that he started in surprise, then shouted:  “Where are you?”

“Here,” replied a voice that sounded so close, so audibly that he looked round in mystification.  Then he saw a deep gulch yawning below him, and caught the flutter of a handkerchief on the far side.  But how could he reach there?  Down he plunged with reckless haste, having little or no regard for his own safety—­and, indeed, he who hesitated here was lost, for at every step the rock crumbled and slid under his weight.

“It will be queer work getting back!” he said to himself, then pressed onward to reach the side of the gulch, where now he could see Mary Selincourt crouched on a narrow ledge or shelf against a perpendicular cliff, while the water was rising higher and higher, creeping nearer and nearer to where she sat.

How could he rescue her from there?  One hope he had, that her shelf might be above high-water mark, in which case patient endurance would be all that was needed until the tide ran out again.  A glance at the wall of cliff behind Mary proved this hope to be futile, for the mark of the water showed above her head, and if she were not rescued speedily, he could only stand by and see her drown.

“Are you hurt?” he called out when he had scrambled low enough to talk to her.

“I have twisted my foot rather badly,” she said in an exhausted tone, “and I seem to have been shouting and whistling for help for so long.  I had great difficulty to make the dog leave me and go for help, but I think it understood at last, because it went off at such a pace.”