“He didn’t say a word to me about the three blue lights,” Clay replied. “We didn’t have any time to talk about such things, and we haven’t any time now, so you fellows just get up here and help fill these tanks.”

All four boys were busy in a moment and young Groger from the store assisted materially in getting the gasoline on board.

In less than an hour all was ready for departure. The young merchant shook the boys heartily by the hand and asked them to call if they returned home by way of the river.

“Oh, we’ll come back all right,” Alex called out. “At least, I’m coming back. I’m bound to know something more about those three blue lights. I’m the original mystery investigator!”

“So father told you about that, did he?” queried young Groger.

“Of course, he did!” Alex replied. “He couldn’t talk about anything else. He seemed to be glad that Clay and Jule saw the three blue lights. I guess he’s got an idea that the people around here think he’s been talking about something that never existed.”

“I’m afraid he is,” replied the young man. “He’s always talking about the three blue lights and the wreck of the Mary Ann, and the explosion, and all that, but he’s the only one about here who ever saw the lights or heard the explosion.”

“Well, you’re mistaken there!” replied Alex. “Clay saw them last night and Jule saw them, and all four of us heard the explosion.”

Watching the young man’s face closely as he stepped ashore, Clay thought that he saw a sudden pallor come over it. The son was evidently as fully superstitious as his father.

“Now, what did the old merchant tell you about the three blue lights?” demanded Jule, as the boat swung off down the river.