Quietly, and without a word to any one, Philip Holt made a secret visit to the house of the three sails. He implored Captain Jules to make him his diving companion. He attempted to bribe him with sums of money that he did not possess. He even threatened the old sailor that he would make investigations about his life and expose any secrets that the captain might wish to keep. Captain Jules only laughed at these threats. He was not going down in the bay for treasures, he declared. He expected to find absolutely nothing of any value. Positively he would not allow any one to accompany him but the two girls. Madge and Phyllis had a hard fight to persuade Miss Jenny Ann to give her consent to their plan for playing mermaid. But she was getting so accustomed to the exciting adventures of her girls that, when Captain Jules assured her there was really no special danger, so long as he kept a close watch on the diver with him, she finally agreed to the scheme. Captain Jules gave the two girls every kind of instruction in the art of diving that he thought necessary, and the day of the great watery adventure was set for the week ahead. On the morning of Tuesday, July 12th, Madge awoke at daybreak. She felt a delicious, shivery thrill pass over her that was one part fear and the other part rapture. "Phil," she whispered a few seconds later, when she heard her chum stirring in the berth above her, "can you feel fins growing where your feet are? Your flop in the bed sounded as though you were a real mermaid! Just think, at ten o'clock sharp we are going down to explore a new world! I wonder if there were ever any girl divers before? You are awfully good to let me go down first." "No, I am not," answered Phil soberly. "If there is any danger, I am letting you go down to it first. But I shall watch above the water, with all my eyes, to see that everything goes right. The captain has explained the whole business of diving to us so thoroughly that I believe I can tell if anything is wrong with you below the surface. You'll be careful, won't you, Madge? You know you are usually rather reckless. Don't stay down too long." "Oh, Captain Jules won't let me be reckless this time. We are not going down into very deep water, anyway, and a professional diver can stay under several hours when the water is only about five fathoms deep." Madge and Phyllis ate a very light breakfast. Captain Jules had told them that a diver must never go down into the water on a full stomach, as it would make him too short-winded. While the two prospective divers were eating poor Miss Jenny Ann was wondering what had ever induced her to give her consent to so mad an enterprise as this diving. Every effort had been made to keep a crowd away from the pier from which Captain Jules meant to send out the boats with the tenders, who were the men to look after the safety of Madge and himself.