“If he is, he swallowed some dust that time,” laughed Stanley. He glanced over his shoulder. The _General Barrill_ was not far now. They could see figures on her decks waving them encouragingly on. “Come on, boys,” shouted Stanley, “a little more steam. That’s it. Now, we won’t be----” A blinding flash filled the air about them. Involuntarily Ned and Herc threw their hands in front of their eyes. It was well they did so, for the quick movement threw Ned out of the path of a jagged piece of metal. It whisked past his ear viciously. A shell had exploded almost alongside them. Before they could uncover their eyes the resulting swell swept down on the boat. Overloaded as she was, the water poured in over her gunwales in a torrent. It was useless to attempt to bail. The detonation of the shell had hardly ceased ringing in their ears before the Americans were struggling in the water, with shells screaming and exploding all about them. [Illustration: The Americans were struggling in the water, with shells screaming and exploding all about them.] CHAPTER XVII. UNDER THE GOLD-STARRED FLAG. As the boat sank under them, Ned struck out for the _General Barrill_. He was a strong, swift swimmer, and almost as much at home in the water as on land or the deck of a battleship. To his intense relief, as he gazed about him, he saw the heads of his three companions bobbing up on the water near at hand. All were safe then. “Swim on your backs,” Ned cried. It was well they heeded his warning, for at that instant there came a shout from Stanley. “Duck!” That was all, but they instinctively obeyed. Even under the water they could feel the jar of the exploding shell which the sharp-eyed man-of-war’s man had spied coming toward them from the fort. “I’ll bet General de Guzman and Charbonde are praying for our deaths harder than they ever did for anything in their lives before,” thought Ned, as he came to the surface. The Americans swam on. Only a few feet now. Already hands were held out to them from the decks of the Costavezan destroyer. “Swim, for Heaven’s sake, swim!” The sudden cry came from the midshipman. In their anxiety to gain the destroyer and avoid the shells from the land batteries, they had entirely forgotten another danger--sharks! As the middy’s cry of warning sounded, a sharp, triangular fin, showing blackly above the blue, came rushing investigatingly toward them. It was followed by another and another. Truly there was desperate need of every ounce of energy that remained in their tired bodies.