Suddenly there came a hail from the masthead: 

“Q’deck-ahoy-sir!”

The boy up there ran his cry altogether in his excitement.  The navigating officer replied.

“Submarine astern, sir!  Can see the periscope bobbing, sir!” was the statement that changed the entire atmosphere of the battleship from that of mere curiosity and interest to the wildest excitement.

CHAPTER XV

THE BIG GUN SPEAKS

The thing the lookout had spied bobbing in the sea was not exactly in the wake of the battleship, for those who rushed to the port rail could see it quite well.  It wabbled about in a most eccentric way, as though the submarine attached to it had risen just as the Kennebunk passed and had received the full force of her swell.

“Jingo! that’s a funny lookin’ periscope,” drawled one second-class seaman, a new recruit, craning his long neck to see over the heads of the group which Frenchy and Ikey had joined.

“What did you think they’d look like?” demanded another.

“Something like a smokestack with a curlycue on the end of it,” was the reply.

Frenchy and Ikey were giggling immeasurably.  The former said:  “Isa Bopp couldn’t beat that, could he?”

“Oi, oi!” sighed Ikey ecstatically.  “A periscope like a smokestack!”

But more than this new recruit aboard the Kennebunk began to doubt the validity of the bobbing thing in the water astern.  The big battleship was being swerved to bring the port broadside to bear upon the now distant object.  The bugle rang for stations.  The sudden activity of the whole ship’s company was inspiring.

Of a sudden there came a hail from the other masthead where two lookouts stood in the cage with glasses.

“On deck, sir!  Submarine just awash on the starboard quarter, sir!”

The cry was in truth a startling one.  Whistler and Torry, who had sprung with their mates to the guns of the second turret, were on the starboard side.  A second submarine?  Why, it seemed the ship was being surrounded by these wasps of the sea.

A sharp whistle sounded in the turret.  The officer in charge sprang to the tube.

“Ready for deflection and range?  Stand by!” was the order.

“Aye, aye, sir!” responded the turret captain.

Ammunition boxes appeared as though by magic and were broken open.  Plugs were swung back and the gun bores were examined.  The starboard gun was quickly charged.  Whistler and Torry both worked on her.  They stood back, the gunner standing with his finger on the button of the trigger.

“That submarine’s going down!” gasped one watcher.  “We’ll lose her.”

The next moment the executive officer’s report for deflection and range came through the tube.  Then:  “Are you on?”

“On, sir!”

“Fire!”

It seemed that almost instantaneously with the roar and recoil of the huge gun the shell burst beside the sinking submarine.  The explosion was terrific; the whole hull of the undersea boat heaved up, exposing its length for a few seconds.  Then the sea-shark sank, going down like a shot.