Stealthily he began to circle the stone structure.  Momentarily he expected to hear the challenge of a sentry; but he was not molested.

In a few moments his foot touched a large flat stone step before a half closed doorway through which the light of the lantern cast its flickering rays.  Jack looked about him for a weapon of some kind and noted a long piece of two-by-four that apparently had been used to prop open the door of the wireless station.  Stooping over he drew the club toward him and then turned to face the door and the danger that lay beyond it.

Fearlessly but with the lithe movement of the crafty panther Jack stepped across the threshold.  As he did so the German wireless operator stirred in his sleep, lifted his head and gazed full upon the American youth.  With a snarl of rage and a muttered curse the burly Teuton sprang to his feet and reached for a heavy revolver that lay on the table.

But Jack was too quick for him.  With a long leap forward and a smashing blow he brought the heavy stick of wood down upon the head of the surprised operator.  The German sank in his chair and slipped to the floor, the revolver rolling off the table with a loud clatter.

Pausing only long enough to note that his captive was completely knocked out by the blow, the Yankee lad sprang to the wireless and opened the key.  Now he was grateful for the wireless instruction good old Sammy Smith had given him back there on the Dewey.

“Z-z-z-z-z-z!” the wires snapped with their message, as he flashed forth the code call of the United States fleet.

Would he be heard?  Was there any vessel within range that would pick up his random call.  For five minutes the boy rattled away and then closed the key to listen.  What was his joy to get an almost immediate response.  It was the U.S.S. Farragut, a destroyer, reporting her position and asking what was wanted.

In rapid-fire reply Jack related the sinking of the Dewey, gave her latitude and longitude, and urged immediate assistance.

“But where in the world are you sending your radio message from?” came the query out of the sky.

“In a German wireless station on the Belgian coast just about six miles
south-----”

But the message was never finished, for at that moment Jack heard a slight movement behind him and turned to look into the revolver of a bulky German who, in broken English, commanded the American to surrender!

CHAPTER XVII

UP FROM THE DEPTHS

Back in the hold of the sunken submarine whence Jack Hammond had made his miraculous escape, stirring scenes were being enacted.  Not a man in the crew but envied Jack in his daring attempt to get away; every man realized that soon it would be his turn.  Either he must follow the example of the one who had gone or face the alternate of a slow and horrible death.