“The crew of the Butterfly will man the Rainbow,” continued Captain Sedley.

The Butterflies seated themselves in the new boat.

“This is merely a temporary arrangement, and when we get the other boats, we shall organize anew.  We want practised oarsmen for our present service.  While we are absent, Uncle Ben will instruct the rest of the boys in rowing.”

Captain Sedley and Mr. Walker then seated themselves in the stern sheets of the Bluebird.

“Now pull for Center Island,” said the former.  “Tony, you will follow us.”

The two boats darted out of the inlet, leaving Uncle Ben in charge of the “recruits.”

The Lily and the Dart were eight-oar boats, while the Dip carried only four, and was designed as a “tender” for the fleet.  Uncle Ben assigned places to the boys, though there were about thirty left after the oars were all manned.  After an hour’s drilling, he got the crews so they could work together, and the boats were then employed in conveying the rest of the party over to the boat-house.  The others in their turn were instructed and before noon Uncle Ben had rendered them tolerably proficient in the art of rowing.

When the Bluebird reached Center Island, Tim had just embarked in the Butterfly, and Barney was preparing to do the same in the Zephyr.  The Rovers were utterly confounded at this unexpected invasion of their domain, and hastily retreated from the beach.

William Bright, who was the coxswain of the Bluebird, ran her alongside the Zephyr, and took her in tow.  In like manner they took possession of the Sylph and the “gondola,” leaving the Rovers “alone in their glory,” with no means of escaping from the island.  With the three boats in tow, they pulled for the beach.

“Now for the Butterfly,” said Captain Sedley, as he placed the Sylph in charge of Uncle Ben, and directed William Bright to steer up the lake.

Away dashed the Bluebird.  The excited crew had observed the Butterfly about a mile off, pulling towards the river.  Tim Bunker, at this safe distance, had paused to observe the movements of the invaders.  He was as much confounded as Barney had been, and seemed to be at a loss what to do; but when he saw the Bluebird headed towards him, he ordered his crew to pull for the river.

“Steady, boys,” said Captain Sedley, when they had approached within a quarter of a mile of the chase.  “Probably they will run her ashore and leave her.”

But Tim did not mean to do anything of the kind, and was running the Butterfly directly for the river.

“They will dash her in pieces, I fear,” continued the director, when he perceived Tim’s intention.  “Pull slowly—­put her about, and perhaps they will return.”

The Bluebird came round; but Tim dashed madly on, heedless of the rocks.

“She strikes!” exclaimed Mr. Walker.

“Round again—­quick!” added Captain Sedley.  “They will all be drowned!  She fills!  There they go!”