It was just four o’clock when they pushed in behind another key and made their way to the mainland, for here the water was quite deep.

“I move for a camp ashore, for a change,” suggested Jerry.

“Second that motion.  My back’s nearly broken from these hard boards,” grunted Bluff.  “Oh, dear!  If we only had our air mattresses along, Frank!”

“Yes, if we only had!” exclaimed Jerry.  “Then you’d soon quit claiming that you had bigger lungs than I’ve got.  You know I beat you in blowing up my bag.”

“Yes, just once more than I came in winner.  Isn’t that so, Frank?”

Frank poured oil on the troubled waters, but he and Will winked at each other, for the joke always amused them.

They erected the tent, and had their jolly campfire, which reminded them of many in the past.  It was, of course, thought a good thing to secure the boat with chain and padlock, so that no prowling scamp could make off with it while they slept, for they meant to keep no watch.

Joe found a place on board, as there was no room in the tent.  Besides, he had not a temperament that delighted in such things, and would only too gladly have always felt sure of having a good roof over him at night.

The four boys were a bit crowded.  Still, they joked over the thing as they settled down, and after a time only the glow of the still burning fire told that human beings were somewhere near by.

They slept soundly, despite the close quarters, since the air was cool, and, for a wonder, no mosquitoes worried them.  Those who were dreaming must have imagined the end of the world had suddenly arrived, for the tent was, without the least warning, knocked down, leaving the four amazed boys scrambling and shouting under the canvas, and trying to crawl out from the wreckage.

CHAPTER XXII

THE MESSAGE FROM THE AIR

“What struck us?” And Bluff poked his head out from under the canvas, looking for all the world like a tortoise, Frank thought, as he followed suit.

“Tell me about that, will you!  Where’s the villain who cut the ropes?  I can whip him with one hand!” panted Jerry, struggling in a mess of camp necessities, and kicking around among the aluminum ware that Frank prized so highly.

“Where’s my camera?  Some fellow has run off with my camera!” wailed Will.

By this time Frank had extricated himself from the wreckage and began to assist the others to regain their feet.  No one seemed to be seriously injured, and the mystery was great.  What had happened to smash down their tent in that strange way?

“The ropes were never cut, fellows!” announced Bluff, after a hasty examination.

“Something fell on us, that’s what!” observed Jerry, shaking that wise head of his in his obstinate fashion as he surveyed the ruins of the tent.

Frank seized upon the idea quickly.