As he spoke there came another crash against the rocks.
"We must electrocute the suckers!" cried the boy.
"Electrocute them? What do you mean?"
"Take the wires from the electric light circuit, attach one to each end of the ship, and start the dynamo at full speed!" answered Jack.
"What good will that do?"
"The ship is steel," went on the boy. "It will become charged with a powerful current. We can insulate ourselves by putting on rubber boots, but the shock of the electricity will kill the creatures!"
"Good for you!" exclaimed Mr. Henderson. "Quick boys, everybody lend a hand! Washington, detach the wires and run one to the bow and the other to the stern of the ship. Then get out the boots."
In a few minutes the dynamo was ready to send a death-dealing current through the entire ship. The professor and all the others put on the boots, that were a part of the diving equipment. The dynamo was started at full speed and the purring hum told that electricity of great power was being developed.
The professor stood with his hand on a switch, ready to close the circuit as soon as sufficient power had accumulated. Once more the suckers backed the ship in order to give it impetus for another impact on the stones.
Click! The professor snapped the switch shut. There was a burst of bluish-green flame, and the movement of the boat suddenly ceased.