"Yes—I believe it was!" said Andy, "It had that throbbing sound that a motor makes. Now what's a motor-boat doing here? But, anyway—it means that we can be rescued!"
"Of course!" said Tom. "Well—let's go and find the motor-boat. What a surprise they'll get when they suddenly see us I They'll wonder wherever we've come from."
"Tom, don't be in so great a hurry," said Andy, pulling the impatient boy down into the heather. "I think there's something funny going on here—and before we show ourselves we'd better find out if we shall be welcome!"
"Oh," said Tom, surprised. The girls looked rather alarmed.
"What do you mean—something funny?" said Jill.
"I don't know, as I said yesterday," said Andy. "But what we will do is to see where that motor-boat is. It won't have seen our signal because it came in the night—and we know it's not anywhere this side of the island, or we would have seen it this morning. I vote we go to that rocky ledge where we get the best view of the second island and see if by any chance a boat has been able to get through the reef of rocks and sail into the quiet lagoon inside."
The four children made their way to the high rocky ledge. Andy made them lie down flat and wriggle like Red Indians as they reached it.
"Better not let ourselves be seen, if anyone is down there," he whispered. So, as flat as snakes, they wormed their way to the rocky ledge—and when they got there, they had the biggest surprise of their lives!
In the quiet water that lay outside the second island was a large and powerful seaplane!
Yes—a great seaplane, whose wings spread widely over the blue water. No small motor-boat purred there. It was the seaplane's engine that Andy had heard so mysteriously in the middle of the night.