"That's the spirit, all right," remarked the official with a grin. "We are proud of you fellows who compose the crew of the _Nemo_ for what you have already done, and we sure are going to take care of you." Jay tried to explain that one man alone had recovered the diamonds and that he was in no sense to be credited with any of the glory. "Just the same, you were there trying hard, and what's more you endangered your own life in an unfortunate accident while in the act of duty." And then the superintendent began telling them why he had summoned them to headquarters. "You chaps doubtless know that the _Jules Verne_ will be ready for her maiden trip within the next two weeks," he began. The boys perked up at this when it seemed likely they were to be let in on the big secret that had every man in the yard guessing. "I can only say at this time," continued Mr. Brown, "that the _Jules Verne_ combines our latest improved method of searching the ocean bottom and has facilities that will greatly expedite deep-sea salvage work. You will know in due time, for you chaps will be among the first batch of divers sent out on the _Jules Verne_. We shall want to thoroughly acquaint you at first with the operation of the new diving bell before you will actually engage in salvage work." The yard official paused to draw several times on his cigar. "In the meantime, I need you for a diving expedition of tremendous importance to Uncle Sam. Are you game?" He looked from one face to the other, eying the boys with a roguish smile. They nodded their heads eagerly. "If it's for Uncle Sammy, lead us to it!" "Well, listen," said Superintendent Brown, as the boys sat wondering what was coming. "An executive officer from the Bureau of Naval Operations in Washington is here on a mission of great importance. It seems the Navy Department has been watching our salvage work, and read about what you boys were doing in the hold of the _Dominion_. They want us to do a piece of work for them that demands speed as well as secrecy." And then he explained in detail. During the war, at the time when a fleet of German submarines had escaped the allied fleets in the North Sea and come to this side of the Atlantic to attack shipping, and particularly supply ships bound for Europe, one of the U-boats had been sunk off Cape May, N. J., at the mouth of the Delaware River. Submarine chasers putting out hurriedly from the inlet had dashed up in time to drop depth bombs on the submerging U-boat. That the U-boat, badly crippled, had been sunk had been established beyond all doubt by navy divers who had located it on the bottom. The Navy Department had intended salvaging the U-boat at once but had been prevented by reason of the fact that the war kept the department busy sending troopships to Europe, guarding them en route and combating the Hun "mosquitoes" that threatened Atlantic ports and coastwise shipping.