"All clear, sir," sang out a petty officer.

With feelings of thankfulness Fordyce put the indicator to half speed astern. Gathering way, R19 slowly backed from the floating cylinders until she was safely out of that danger zone.

"Well done, Mr. Fordyce!"

The Sub turned, flushed with pleasure, and smartly saluted. It was the Hon. Derek who had spoken. Throughout the hazardous operation he had stood quietly behind his young subordinate, ready to take charge if necessity should arise. But there had been no need, and Stockdale was too shrewd a man to "barge in" and flabbergast his youthful Sub.

"Mine right astern, sir!" shouted a seaman.

"And to starboard, sir!" announced another.

R19, in backing from one danger, found herself beset by floating perils on all sides.

CHAPTER IX

Drifting Mines

It was a situation in which skilful handling and consummate coolness alone would extricate R19 from the perils that encircled her. To attempt to back astern or forge ahead in the hope of escaping the floating mines would be courting disaster. Fortunately there was little to fear from partly-submerged anchored mines, for the depth of the Skager-rack was here not far short of four hundred fathoms. On the other hand, the drifting mines were either in pairs or in multiples of two, connected by lengths of wire of sufficient length to cause the explosive cylinders to hit amidships the hull of any vessel unfortunate enough to pick up the middle part of the bight of rope.