Lieutenant Stein sprang to his feet, hastily donned what few clothes he had removed, and dashed from the cabin. With all possible haste, the boys followed suit.
Men were rushing to and fro and no one heeded the boys' presence, although they were rudely thrust aside by hurrying members of the crew several times.
"Wonder what's up?" said Jack.
"Don't know," replied Frank, "unless they have sighted one of our ships."
"By Jove! Let us hope not," breathed Jack.
But this was indeed the cause of the excitement aboard the submarine. A British battleship had been sighted in the distance, and Captain Von Cromp was preparing to attack the unsuspecting vessel, which had failed to sight her enemy, although the latter was fully exposed to view.
Frank and Jack approached the foot of the periscope, where they stood awaiting developments.
Outside a sudden storm swept the water of the North Sea in angry waves. The water lifted up the little vessel with the regular motion of a high-running sea. All was pitch dark.
The fact that men were hurrying about on deck, was only shown by the somber figures who now and then passed in front of a single lantern. From out the engine room, already under water, arose the pound of heavy pounding and the weird crackling of the engines, as they were tried out.
Jack glanced at his watch. It was 10:30. Suddenly there came a shrill whistle from the little bridge of the submarine, standing high above the vessel, and covered with heavy canvass. The officer in command, Captain Von Cromp himself, dressed hi heavy oilskins, raised a hand, the signal to go ahead.