"Are you going to use the other loaded torpedo to-day, sir?" asked Jack.

"Against _what_?" demanded Danvers. "You've sunk the scow as deep as
the bottom of the Atlantic Ocean."

"Then I suppose we may as well put back to Dunhaven, sir?"

"Yes, Benson."

Jack accordingly signaled for slow speed ahead, turning the nose of the
"Hastings" toward the west. Hal and Eph, as the submarine started back,
took a drill in loading and unloading torpedoes into the tube, performing
this work with one of the dummies, Ewald and Billens assisting.

Knowing that Hal was not in the engine room, Captain Jack was content
to run along at slow speed. Nor had the boat gone more than two miles
when something struck the bow.

At the first impact alert Jack Benson felt his heart leap into his
mouth. It was as though the "Hastings" had struck, lightly, on a
reef. Almost by instinct Jack threw the wheel over to port. Something
was rasping, forcefully, under the hull of the submarine. As the helm
went to port that something underneath, whatever it was, sheered off.

"What was that, Benson?" called up Lieutenant Danvers, sharply.

"Struck something, sir, I'm sure," Jack called back.

At the first sound of trouble, Hal Hastings leaped into the engine room.
Lieutenant Danvers sprang up the stairs into the conning tower. He was