Almost at the same instant Frank, who had kept his eyes glued to the deck of the Ventura where the struggle on the bridge had continued fiercely, uttered an exclamation of alarm.
"They've broken away," he cried.
It was true, The submarine commander and his followers had succeeded in eluding the crew of the Ventura and dashed to the rail. There they poised themselves a brief moment, and then flung themselves headlong into the sea. Directly, dripping, they appeared on the deck of the submarine and dashed for the conning tower.
"Quick!" roared Jack. "Forward turret guns again there!"
Once more the range was calculated and an explosion shook the Essex. But as before the range had not been true. The shell barely skimmed the top of the U-Boat and went screaming half a mile past, where it struck the water with a hiss.
Slowly the submarine began to submerge.
"Again!" cried Jack.
But the next shot had no better success.
The submarine disappeared from sight.
Jack stamped his foot.