"Get inside and we'll sink below the surface!" called Tom. "Then we don't care what happens."
They closed the steel door of the conning tower. As they did so they heard the patter of bullets from carbines fired from the San Paulo. Then came a violent tossing of the Advance; the waves were becoming higher as they caught the full force of the hurricane. It took but an instant to sever, from within, the cable attached to the anchor, which was one belonging to the warship. The Advance began drifting.
"Open the tanks, Mr. Sharp!" cried Tom. "Captain Weston and I will steer. Once below we'll start the engines."
Amid a crash of thunder and dazzling flashes of lightning, the submarine began to sink. Tom, in the conning tower had a sight of the San Paulo as it drifted nearer and nearer under the influence of the mighty wind. As one bright flash came he saw Admiral Fanchetti and Lieutenant Drascalo leaning over the rail and gazing at the Advance.
A moment later the view faded from sight as the submarine sank below the surface of the troubled sea. She was tossed about for some time until deep enough to escape the surface motion. Waiting until she was far enough down so that her lights would not offer a mark for the guns of the warship, the electrics were switched on.
"We're safe now!" cried Tom, helping his father to his cabin. "They've got too much to attend to themselves to follow us now, even if they could. Shall we go ahead, Captain Weston?"
"I think so, yes, if I may be allowed to express my opinion," was the mild reply, in strange contrast to the strenuous work in which the captain had just been engaged.
Tom signaled to Mr. Sharp in the engine-room, and in a few seconds the Advance was speeding away from the island and the hostile vessel. Nor, deep as she was now, was there any sign of the hurricane. In the peaceful depths she was once more speeding toward the sunken treasure.