Sunday passed quietly and two days later found the Firefly steaming slowly along the coast of Yucatan. The yacht had several drags out, drags which had been constructed by the head diver, and his assistant after consultation with the captain and the mate.

“After all it’s a good deal like looking for a needle in a haystack,” sighed Fred, as hour after hour went by without results.

“It won’t do to get discouraged so early in the game, Fred,” answered the captain, with a grim smile. “If we go over a few miles of the bottom around here every day, we’ll be doing very well.”

From a section of the regular chart the captain had constructed a much larger affair, and this he had divided into numerous squares.

“We’ll go at this thing systematically,” he said. “We’ll try to take one square at a time, and thus sooner or later we’ll have a pretty good idea of what is on the whole bottom around here.”

Once or twice other vessels came close, wondering what they were doing. But generally speaking, they were unmolested, several Mexican fisherman, however, gibing at them when they guessed they were looking for a treasure.

“Ha-ha! That’s an old story,” said one of them. “If you’re lucky you may bring up some old anchors or sea boots, and that will be all,” and, lighting a cigarette, he waved his panama hat and sailed away.

“Evidently those fellows don’t believe much in a treasure,” was Jack’s comment.

Day after day went by and the search continued, but without results. Then the boys grew a bit depressed and so did the captain and his mate.

“Looks a bit like a wild-goose chase,” was the way Nat Brooks expressed himself. “It seems to me we’ve been raking over miles and miles of Gulf bottom and got absolutely nothing for our pains.”