Situated far to the rear of the target as they were, Herc knew that those in the boats had not sighted him, and unless he was missed from the Number One whaleboat, his doom was sealed. He could have screamed aloud with real terror at the peril of his situation. At almost the same instant his burning eyes saw a burst of flame suddenly flash from the side of the battleship. Herc's brain reeled. Already he could hear the scream of the shell, and in fancy saw his dismembered body flung in torn fragments before it. "Phsiwis-is-s-s-s-s-s-s-s-s!" The projectile shrieked nearer and nearer and passed like a thunderbolt through the target, ripping it from top to bottom with a vicious hiss. It plunged into the sea far beyond, ricocheting from wave to wave for two miles or more. But the float was empty of life. Herc had vanished. CHAPTER XXI. AFLOAT AND ASHORE. The petty officer in command of Number One whaleboat noted the effect of the shot and then looked about for Herc. As we know, the red-headed lad was not on board, nor did any inquiry among the crew bring a satisfactory explanation of his whereabouts. The men had seen him standing on the stern, and then had lost track of him. They had supposed that he was "somewhere on board," they said. Kennell alone volunteered an explanation. "He may have tumbled overboard, sir," he suggested. "I saw him standing up in the stern-sheets as I cast off with my boathook." "We must communicate with Ensign Rosseau at once," said the officer, greatly agitated. He knew that a searching investigation would follow the loss of a man, and he foresaw that he would appear in no very creditable light without any explanation to offer as to the manner in which Herc had vanished. [Illustration: The triangular fin was now close upon the lad.] Rapidly the whaleboat was rowed to the wherry, which "lay to" some distance away, with the Number Two whaleboat alongside. The tidings of Herc's loss were received with some anxiety by the ensign. He turned to Ned, whose face had gone white at the news, and asked curtly if Herc could swim. "Like a fish, sir," was Ned's rejoinder, although he had hard work to keep his lips from quivering at the thought of his friend's possible fate. "Then there is a chance that he can be saved yet," breathed the ensign; "give way for that float yonder. Strong, signal the news to the flagship and inform them that we are standing by." Ned, badly unnerved as he was, made the necessary signals, and received an order to "carry on" from the flag-ship. The two whaleboats and the wherry at once got under way for the target near which Herc had last been seen. Suddenly Ned gave a shout and pointed ahead. "Look, sir, look!" he cried. Not more than a hundred feet from them a rubicund object, which a second glance showed to be Herc's head, was bobbing about on the waves.