It was a standing order, however—at least until the younger men became more experienced with the wireless—that Lieutenant Mackinson immediately should be apprised of the sending or receiving of any messages.
This first evening out the lieutenant complained of a headache, and, acquiescing in Joe's urging, had gone upon deck to get the air. Perhaps fifteen minutes had elapsed when Joe thought he heard someone prowling about stealthily in the battery room.
His first thought was that the lieutenant had returned to make certain that everything was all right, but a moment's consideration convinced him otherwise.
Whoever was in the adjoining room was making every effort to keep his presence there from becoming known!
It gave Joe a queer sort of feeling. What should he do? To seek the lieutenant and bring him back might require several minutes. Meanwhile the intruder might accomplish his object—whatever it was—and disappear.
He decided to act upon his own initiative. Tiptoeing across the room, he turned off the electric switch, which threw the wireless room into utter darkness except for the meagre moonlight filtering through an open porthole.
Then, just as silently, he re-crossed the room to the door leading to the battery room; slowly and without a sound he turned the knob and opened the door to a sufficient width to permit him to peer in. That room also was in darkness, with only one porthole open.
Cautiously the intruder seemed to be feeling about for something connected with the batteries.
Listening intently for a moment, to get the exact location of the other man, Joe flung open the door and made a flying leap in the other's direction. The man was leaning over, and Joe landed squarely upon his back.
With a muffled exclamation of surprise the man jerked himself forward and Joe went hurtling over his head, his arms, however, still clasped tightly about the other man's neck.