"I know where we are," said Captain Krell. "Wait a moment; I'll get the chart, so you may all study it."
He brought it from his cabin and spread it upon a folding table on the deck. A penciled line ran directly from the port of San Diego to a point south by southwest.
"A few more hours on the same course and we'd sight the little island of Guadaloup, off the Mexican coast," explained Captain Krell. "But the aëroplane couldn't go so far; therefore we must search on either side the course we've come."
They all bent their heads over the map.
"What are those unmarked dots which are scattered around?" inquired Mr. Cumberford.
"Islands, sir. Mostly bits of rock jutting out of the sea. They're not important enough to name, nor do they appear on an ordinary map; but a seaman's chart indicates them, for unless we had knowledge of their whereabouts we might bump into them."
"They're mostly to the south of us, I see," remarked Mr. Tupper.
"Yes, sir."
"And it's south we must go, I think," said Steve, looking at Chesty Todd for the youth to confirm his judgment. "There was no wind to take them to the west of this course, I believe."
"That's my idea," declared the press agent. "I would suggest our doubling back and forth, on the return trip, covering forty or fifty miles at each leg. Seems like we couldn't miss 'em, that way."