an air compressor, and a small condenser, by means of which sea-water could be made drinkable. In the after compartment was located a compact but powerful gasoline engine. This furnished the motive power for running on the surface, and also stored electricity by which the screw could be turned when surface air was no longer available. Beneath the floor of the central compartment was a tank for water ballast, which could be filled or emptied at will of the operator. In all parts of the boat were hundreds of tubes, wires, cocks, valves, and other devices of amazing ingenuity for ensuring the safety of her crew and the discomfiture of an enemy.

She was indeed, as Carlos Moranza had said, one of the crowning scientific marvels of the century. On the day succeeding that of her trial trip, the young Cuban was full of hope and courage, for Professor Rivers had been won to his cause by the enticing prospect of achieving the rescue of a young girl from a dreadful fate, and at the same time testing under most trying conditions the powers of his beloved boat. He had only stipulated that she should not be used for the destruction of either life or property.

Thus it happened that in less than a week one of the most powerful tugs on the Delaware cleared for Havana. She had in tow a great dumping scow, such as is used in New York harbour for conveying the city garbage far out to sea. This scow was built with a long central pocket, the bottom of which was longitudinally divided into two parts. Each of these was hung on massive hinges, and could be made to drop or open outward, thus allowing the contents of the pocket to fall into the sea. Then, by means of a donkey-engine, the great valves could be drawn up and closed as before.

The question of how to get the Mermaid to Havana had proved most puzzling. She was too small to undertake such a voyage by herself, and had she been shipped on the deck of another vessel, her every movement would have been watched and heralded, while the success of the proposed expedition depended upon its secrecy. Thus, at the very outset, the would-be rescuers seemed to be confronted by an insurmountable difficulty. Then Carl Baldwin had thought of the sea-going dumping scows, several of which had been built in his father's shipyard, where one recently completed even now awaited a purchaser.

"Why couldn't we take the Mermaid to Cuba in it?" he suggested, after several other plans had been dismissed as impracticable.

"The very thing," cried Carlos Moranza. "In that way we could carry her right into Havana 

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