UNDER THE EARTH.

The boat’s pace decreased and then came another sharp command:

“Stop her!”

The light flashed on a sort of platform of rock ahead of them, a natural dock in this subterranean harbor. The white rays showed numerous bales and boxes piled all about and also a rough sort of table with tin cups and dishes on it, and in one corner, blackened with smoke, was a pile of rocks apparently dedicated to use as a cooking range.

“Well, of all the odd adventures,” thought Nat to himself as the motor craft was run alongside the rock shelf, “this is the queerest I’ve encountered, and all within striking distance of home, too, that’s the strangest part of it.”

But he was not given much time for reflection. Old Israel, in a gruff voice, bade him get out and climb up on the rock platform. There was nothing to do but to obey and Nat clambered up on the natural dock and was followed by the others. The searchlight was extinguished and the place was momentarily plunged into an abysmal darkness. But presently old Israel produced some matches and lit a large lamp that stood on the rude table.

“Better make yourself at home,” he gruffly advised Nat, “you may be here for quite a while.”

Nat gave a sigh of resignation. Had it not been for the anxiety he knew his friends must be feeling about him he could easily have found it in his heart to rather enjoy this weird adventure. As it was, though, he felt anxious and worried over what they must be thinking.

Seth and his brother set about preparing a meal consisting of fried fish, potatoes and coffee, with flapjacks. When it was ready they were all summoned to sit down and eat, and Nat took his place with the rest of them. He had the hearty appetite of energetic, healthy youth, which even his dilemma had not dulled.

During the meal old Israel and Minory sat apart conversing in wrangling tones. Nat judged that there was some hitch over the payment of the money that had been promised by the latter as the price of the Harleys’ aid. However, at length everything must have been patched up amiably, for the two shook hands as though cementing a bargain. Nat caught them looking at him once or twice, but deemed it wisest not to let them know that he was aware of this fact.

After the fish and the rest of the food had been disposed of, Nat was told that he could do what he liked. Having found an old newspaper, the boy sat down close to the lamp and began perusing it. But it was dull work and speedily palled, and he amused himself by exploring the cavern. The rock shelf extended back about twenty feet and was some forty feet across the front. It might, in fact, be compared to the stage of a theater as aptly as anything else, with the rock walls of the cave forming the proscenium arch.

Whether it was altogether natural in formation Nat could not, of course, say, but he recollected having heard that many such caves existed, and that in the days of the Spanish occupation they were used by the coast Indians as hiding places from their masters. In one or two places on the walls of the cavern he thought he saw traces of rough carvings which appeared to bear out this idea.

Another thing that he noticed, and one which set a bold plan buzzing in his head, was a small boat moored to the front of the rock platform not far from where the black motor boat had been tied. The boy was careful, however, not to let his eyes dwell too long upon this, as the desperate scheme he had half formed in his mind might have been killed in the making had his captors suspected that he had observed it.

Hour after hour went by; it seemed like an eternity to Nat, and at last he began to find himself getting sleepy. Finally he could fight off his drowsiness no longer, and, giving in to it completely, he flung himself on a pile of old sacking in a corner of the cave and immediately dropped off into profound slumber.

How long he slept he had no means of knowing, but when he awakened again the cave was empty, save for Seth, who sat at the table whiling away the time by hacking something out of a bit of wood with his knife. At last Seth began to blink and wink, and apparently in order to keep awake, he walked over to where Nat lay, seemingly still wrapped in slumber.

“Humph!” Nat heard him say to himself after a long inspection, “that younker’s good for twelve hours’ snoozing after that stuff pop gave him to make him sleep. I reckon there’s no harm if I take forty winks myself. Anyhow, there’s no chance of his getting away.”

So saying, he slouched back to the table, and burying his face in his hands, dropped off into what, to judge by his snores, must have been a sleep as deep as the one from which Nat had just awakened. Nat waited for a while to let Seth get well into the land of Nod and then, with his heart beating like a pneumatic riveter, he arose and crept cautiously toward the small boat he had observed earlier in the night.

For one moment the wild idea of taking the motor boat had flashed through his mind, but he abandoned the idea as it was pretty certain that either Seth or old Israel had pocketed the switch blade or otherwise made it impossible to start her without their knowledge. As he cautiously made his way to the edge of the platform and toward the small boat, Nat found himself wondering what had become of the others. The motor boat was still there, so that obviously they could not have used her in their departure.

“There must be some other way out of the cave,” thought Nat. “Don’t I wish I knew where it is? But with luck this way will prove just as well, provided Seth doesn’t take it into his head and wake up.”

Nat dropped into the small boat and cast her off without Seth’s stirring.

The tide must have been setting out, for the boat at once drifted away from the platform toward the mouth of the cavern. The boy had drifted some distance before he thought it safe to take to the oars. Right there and then he made a startling discovery. Small wonder the boat had been left unguarded. There were no oars in it!

“Great Scotland!” exclaimed Nat in a voice of consternation, “this is worse and then some! However, I’m in for it now and must make the best of it, but, in case Seth wakes and takes after me with the motor boat, I’m a goner, sure.”

Drifting along on the outsetting tide, the boat rapidly got beyond the glow diffused by the lamp beneath which Seth was sleeping, and glided with its helpless occupant into the pitchy darkness of the sea cavern.