“Hurrah! just the thing!” exclaimed Sam.  He did not relish the long tramp through the thorn bushes and tangle of vines.

Dick’s idea was acceptable to all, and they set off without further delay.  They took the path leading to the shattered cave, and then mounted the small hill Dick had mentioned.  Close to the top stood a large tree.

“Let me go up!” exclaimed Tom, who could climb like a cat, and he started without delay.

“Look out that you don’t break your neck!” cried his parent.

“I’ll be careful,” answered the fun-loving youth.  “This just suits me!” he added, enthusiastically.

“Can’t I go, too?” asked Sam.

“If you are careful,” answered Mr. Rover, and up went the lad, right on the heels of his brother.  It was rather difficult work getting from limb to limb, for some were wide apart, but the vines, which used the tree as a trellis, aided them greatly.  Soon Tom was close to the top and Sam speedily joined him.  Then each took his turn at looking through the spyglass.

“I see the Rainbow!” cried Tom.  “She is headed for the north side of the isle.”

“Yes, and yonder is another vessel,” returned Sam, as he pointed the glass in the direction.  “That must be the Josephine.”  And then the two youths shouted the news to those below.

After that the boys watched the progress of the steam yacht with interest, keeping those below informed of all that was going on.  They saw the Rainbow draw closer to the other vessel, and saw the small boat leave the steam yacht.

“Four men are rowing to the other vessel,” announced Tom.  “We can’t make out who they are.”

They saw the four men board the other vessel and disappear, presumably into the cabin.  Then came a wait of over half an hour.

“This is getting tiresome,” said Tom.

“You can go below if you want to,” answered Dick, who had come up, followed by Songbird.

Tom descended to the ground and Sam followed him.  They had just done this when there came a cry from Dick: 

“Two boats are putting off from that other vessel!  Each of them is filled with men!”

“Are they coming ashore or going to my yacht?” demanded Captain Barforth.

“They are heading for the yacht!”

“They intend to capture the Rainbow!” groaned Mr. Rover.  “Oh, if only we were on board!”

In his anxiety to see what was being done, he climbed the tree and so did the captain.  Then the others came up, the tree being large and strong even at the top and capable of holding a good weight.

“If those rascals try to take my vessel I’ll have them all hung!” roared Captain Barforth, and trembled with rage.  “Oh, if only I was on board!” And he clenched his fists.

“Look! look!” ejaculated Dick, who had the spyglass.  “I think—­yes, the Rainbow is moving!”

“Moving!” came from the others.