Harry threw a plank, and Mr. Mole being fortunate enough to clutch it, was thereby enabled to keep himself afloat.
But he was exposed to another danger.
The shark being irritated by the rusty iron in his throat, was rushing hither and thither in a most furious manner, snapping his jaws in a way that made the spectators thankful they were on deck.
And then, turning on its back, it bit at Mole.
"Help, help!" shouted Mole.
"Oh! the brute has taken my leg off."
The shark resumed its natural position, and held Mole's stump above water, puzzled to know what to do with it.
"This is my fault," said young Jack, and seizing a cutlass, he leaped overboard.
"Lower away the boat," shouted Dick Harvey, who had just come on deck.
He and Jefferson had also armed themselves, and were about to leap in to young Jack's assistance, when Harkaway senior appeared.