"I should like to know what is the good of learning physics," said the Doctor, smiling, "if they can't help a man at a pinch like this. Haven't we an electric battery, and long enough lines attached to it to serve our purpose? We can fire our mine whenever we please in an instant, and without the slightest danger."
"Hurrah!" exclaimed Johnson.
"Hurrah!" echoed the others, without heeding whether the enemy heard them or not.
The Doctor's idea was immediately carried out, and the connecting lines uncoiled and laid down from the house to the chamber of the mine, one end of each remaining attached to the electric pile, and the other inserted into the keg of powder.
By nine o'clock everything was ready. It was high time, for the bears were furiously engaged in the work of demolition. Johnson was stationed in the powder-magazine, in charge of the cord which held the bait.
"Now," said Clawbonny to his companions, "load your guns, in case our assailants are not killed. Stand beside Johnson, and the moment the explosion is over rush out."
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"All right," said Altamont.
"And now we have done all we can to help ourselves. So may Heaven help us!"
Hatteras, Altamont, and Bell repaired to the powder-magazine, while the Doctor remained alone beside the pile.