another sharp snap, and the boy fell backward, dazed.

He heard the man run swiftly, almost noiselessly toward the stern of the
ship; brilliant and many-colored lights flashed before his eyes--and he
knew no more.

[Illustration: There was an Instant of Terrible Whirling about the Room.]

CHAPTER VI

THE MYSTERY OF THE IRON CROSS

When Joe came back to consciousness it was with his head pounding
terribly, and Lieutenant Mackinson bending over him, swathing his face
with a cool wet cloth, while Jerry and Slim, whom the lieutenant had
wakened, were standing nearby, one holding a basin of water, the other a
bottle containing a liniment or lotion.

"You've been done up pretty badly," said Lieutenant Mackinson, as Joe
went through the painful motion of moving his head from left to right,
letting his gaze take in the now lighted wireless room.

"Yes," he answered with an effort. "Nothing serious, though, I guess."
And then, full recollection coming to him, "Did he get away?"

"Who?" asked the lieutenant quickly. "Who was it beat you up so?"

"I don't know," Joe answered. "I discovered him in the battery room. We
fought in the dark."

With the aid of the others he raised himself to a sitting posture, then
stood up and walked rather unsteadily across the room, took a long quaff
of cold water and dropped heavily into Lieutenant Mackinson's Morris
chair.

At the same time he gazed for the first time at what he had been holding
tightly clutched in his right hand ever since the knockout blow had been
delivered. The other three also were staring at it in open amazement.

"What is it?" asked Joe, as the lieutenant crossed the room and took the
thing from him for a closer examination.

"What is it?" Lieutenant Mackinson repeated. "Why, lad, this is the
German iron cross! Tell us what happened here."

With the young officer seated before him, and his two pals standing at
either side of his chair, Joe, quietly, quickly and as carefully as he
could, gave them every detail of the occurrence, from the moment he had
first heard sounds in the battery room, to the time that the other man
ran away and he lapsed into unconsciousness.

While Joe was relating his story the lieutenant examined and re-examined
the iron cross, the bit of broken chain still attached to it, and the
piece of brown woolen army shirt which the lad had torn away with it.
As the latter finished, the young officer hurried into the battery room,
acc