CHAPTER XXXIV.

THE TUNNEL ENTRANCE.

The tender was a light one. It was no very hard task for the party to draw the little craft up the beach and into the concealment of a clump of bushes.

Hardly had this been done, when around the point behind which they had landed, came the craft they had heard. The night was starlit, and in the dim radiance they could see her dark outlines coming on at a good speed.

Beyond the little cove into which they had drawn the tender was a fairly high cliff, rocky and threatening. The motor boat crossed the little cove and kept straight on. No lights burned on her. Plainly her errand was not one which those on board cared to advertise.

“Great Scott! what is she going to do?” exclaimed the inspector, in a low whisper, as the motor boat kept right on across the little cove without altering her course in the least. Not one degree did she swerve from the route she was steering.

“What on earth do they mean to do?” breathed Ralph. “Run the boat smack into that cliff?”

“Looks as if they are bent on suicide,” commented Jennings uneasily.

“I told you it wasn’t any ordinary kind of boat,” said Harry Ware. “It wouldn’t surprise me if——”

“Jumping Jupiter!” burst from the inspector.

The rest of the party could only gasp their amazement. At the moment articulate speech was impossible.

The motor boat had reached the cliff—and vanished without sound or sign.

“She’s gone down!” cried Ralph, the first to recover from his astonishment.

“Gone down, nothing!” retorted Harry scornfully. “She’s just melted into air, that’s what.”

“Don’t be so foolish,” chided Inspector Jennings. “Depend upon it, that is another of their tricks, like the ones they played on you, boys.”

“We’ll start for that cliff and examine it,” declared the chief inspector. “There’s some clever sleight of hand in all this mummery.”

“We’re going to that cliff!” gasped Harry, in affrighted tones. Nevertheless he set off with the others, but he might have been observed to hang some distance behind them. The boy was now more firmly convinced than ever that there was something supernatural about the mysterious craft.

“The Fenians had all sorts of secret ways of landing upon and leaving this island,” said the chief inspector; “and I’ll wager that the motor boat just used one of those to work the trick we’ve just seen.”

The night was warm and there were occasional flashes of summer lightning. To Harry’s thinking, this made the strange quest they were engaged on all the more uncanny.

At last they reached the cliff.

“I wish another flash would come,” said Ralph, “we daren’t light matches. But I brought along an electric torch.”

“A good idea. We may need it later,” said the inspector. “Hullo! Look there! I guess that explains the mystery of the motor boat’s vanishing.”

Another flash had revealed a tunnel-like hole in the cliff which could hardly be observed from the water side, on account of several thick bushes which grew, either by accident or design, about its mouth.

“There’s a path,” said Ralph presently, as another flicker of lightning revealed a rough trail leading up the cliff face.

“We’ll follow it. Easy, now, boys, we don’t want to give the alarm,” warned the chief inspector.

Through the darkness the intruders on the gem smugglers’ realm crept up the slippery track. At last they gained the top. Below them, as the flickering flashes showed, was a big pool of water, either natural or artificial. Doubtless the tunnel through the cliff led into it, for moored to one side of the pool could be seen the mysterious motor boat.

There were no lights on board her. Apparently those who had arrived at the island had made their way up the hill to the windmill tower, for a light could now be seen gleaming, like an angry eye, half-way up the structure.

“They’re all up there. Collecting their effects preparatory to leaving the island forever, I imagine,” whispered the inspector. “Let’s have a look at their boat.”

It was a rather risky business, but still they were a strong party and the government officers were well armed. The descent to the side of the pool was made by a rocky path very like the one by which they had ascended the cliff.

Harry hung back while the others inspected the boat. But Ralph rallied him after a short time.

“She’s all solid, Harry,” he declared; “come on and see for yourself. Nothing ghostly about this fellow, unless a sixty horse-power motor of the best and speediest design appeals to you as being spookish.”

Harry came forward and soon satisfied himself that it was all as Ralph had said. Inside the boat they found tubs of phosphorus, for producing the ghostly effect that had so scared Harry, plenty of spare lanterns to work the stern-light trick and a stern search-light of great power, evidently intended to be thrown full in the eyes of the helmsman of any pursuing craft and dazzle his vision.

In a locker, too, were sheets with holes for heads and a number of masks painted to resemble grinning skulls.

“Quite a paraphernalia,” grinned the chief inspector. “All this would make a regular eight-hour-union ghost turn green with envy.”

In a small shanty which stood close by they found more evidence to show how the operators of the _Artful Dodger_ had been practicing on the credulity of the islanders. All sorts of rigs and canvas frames by which the outlines of the motor boat might be altered at will were discovered. For instance, one frame was found which could be hooped on to the boat’s stern, changing her whole appearance. A false cabin top was also found, by means of which the _Artful Dodger_ could be speedily converted to a cabin cruiser, in case any one was looking for a motor boat of another type.

“Well, this is the most complete layout we have uncovered for some time,” spoke the chief inspector. “I think——”

But Ralph interrupted him.