"Don't tell me," he cried, "of your `whitehead' going twenty knots an hour and exploding its charge of gun-cotton under a ship's bottom; for, where and what would those on board the ship be doing all the time-- standing still, I suppose, to be shot at and doing nothing in their own defence?" "Aye, that's true, sir," said Hellyer; "but--" "Remember, too," continued the Captain, "the torpedo, even of the most improved type, can only keep up this speed of twenty knots for a distance of five hundred yards, within which range the boat discharging it would have to approach before sending it off at the vessel attacked, which of course would be fool enough to let it come to such close quarters without riddling it? Oh, yes, you tell that to the marines!" Hellyer laughed. "You carry too many guns for me, sir," said he good-humouredly. "I can't stand up against you, Captain, once you tackle me fairly!" "Too strong, eh?" rejoined the Captain, triumphant at getting the better of his opponent. "Of course I am! Your argument, Hellyer, won't hold water. Besides, should one of those spiteful little inventions succeed in getting near an ironclad without being seen and sunk, the torpedo nets of the ship would prevent the infernal machine, as these new- fashioned fallals were called in the old days, from exploding against her hull. I, for my part, would be quite content to stand the brunt of a torpedo attack on board a ship fitted with protecting nets and quick- firing guns. By Jove, I'd guarantee that Jack Dresser wouldn't be the one that was licked!" "I'd bet that same, sir," agreed Hellyer heartily, but seeing Bob he added, "Ah, here's the young ge'man I fished out of the sea t'other night. He doesn't look any the worse for being nigh drownded. He warn' hurt, sir, much, were he?" "Not he," said the Captain. "He's learnt to swim, though, since then, and the other boy, too; so, if they choose to tumble in again off the ramparts and get into deep water, there won't be so much bother in hauling them out; eh, Bob?" "No, Captain," replied Bob, who was busy undressing; and, within a few moments he had plunged into the sea, and was swimming out with a brave firm stroke in a way that fully justified the Captain's praise of his natatory powers, shouting out at intervals his customary war- cry--"Jolly!" Nor was Dick far behind, although perhaps not quite so plucky in venturing beyond his depth, now that he had no especial motive as on that memorable evening already alluded to by Hellyer the coastguardsman, for running the risk; while, as for Rover, he fairly revelled in the water, paddling round and round Bob and Dick, thereby executing a series of concentric circles never dreamt of by the Egyptian mathematician whose problems have been the torment of the boys of all ages.