"How?" asked Andy Flures.
"I'm going to charge every metallic part with a sufficient voltage of good old electric juice to give the shock of his life to anyone who lays his hands upon those parts," Fred answered.
"That's the best idea yet," agreed Jack enthusiastically. "That is, providing you can give it sufficient voltage."
"Well," Fred went on, "I'll connect up enough of the juice that even if it won't hold a man it'll bring such a surprised yell out of him that anybody within a hundred yards will know he has touched something hot."
CHAPTER IV The Tamperer Captured
As a preliminary to his plans for catching this dangerous meddler red-handed if he ever returned to meddle again, Fred first asked Big Jack to return to their hut and bring up to the hangar a box of heavy and powerful auxiliary batteries which had come to them by express, to be carried along on their flight for use in any emergency in which the electrical equipment of their plane, either with respect to engine or radio service, might go wrong.
While Jack was on this errand, Fred set Donald to work digging a hole beneath the plane large enough to contain this battery box when it should arrive.
With the aid of Andy he began the secret wiring of the plane in such a way that the wires could be charged without danger of damage to any of the vital parts of the plane—and it may be said here that practically every part of an aeroplane not only is essentially vital, but vitally essential.