“Steady, now!” called Jacob Farnum, in low tones.  “We’ve six hours in which to make up a few seconds.”

If Captain Jack heard, he gave no sign.

For the next few minutes the youthful commander seemed to forget everything but the wheel under his hand, and the course and speed of the craft he commanded.

That the “Benson” was slowly losing was not, at first, clear to anyone on board.  It took time to draw out the increasing lead of the other craft, but, after a while, it became more and more evident.

True, the “Benson” was second in the line—­but the “Zelda” was first.

At the end of an hour there were drops of clammy ooze on Captain Jack’s forehead.  He was steering as well as he had ever steered in his life.  Hal had sent up word that the “Benson’s” engines were doing all that could fairly be required of them.

That troublesome hour up, Captain Jack called to Eph to take the helm.

A few moments later the youthful commander appeared again on the platform deck, carrying a range-finder on a tripod.  Through the telescope he took some rapid sights, then did some quick figuring.  When he looked up Benson saw Jacob Farnum standing within four feet of him.  The shipbuilder’s face looked gray and haggard.

“How much?” asked Jacob Farnum.

“Shade more than a quarter of a mile in the lead of us, sir,” Jack replied.

“Have you been down to talk to Hal?”

“What’s the use, sir?” demanded Jack.  “Hal Hastings knows how much depends on speed.  He’s doing everything that his engineer’s conscience will allow.  Besides, David Pollard is there with him, sir.”

“I’ve no orders to give,” Jacob Farnum sighed, stepping back.  “You youngsters know what you’re about, and how much depends upon our success to-day.”

Indeed, Jack Benson knew!  As he silently took his place at the wheel again deep lines appeared in his youthful face.  He knew, this forenoon, what it meant to suffer.

At the end of the second hour, Jack again called Eph to take a short relief trick at the wheel.  But Jack, instead of resting, promptly placed the range-finder.  As he tried to adjust the telescope the submarine boy’s hands shook.  Jack glanced over at Lieutenant Danvers, cool and impassive.  Danvers knew all about working that range-finder.  But the naval officer was aboard as an official spectator.  If the lieutenant aided in any way, then the Pollard submarine would be disqualified.

Jack’s work was more slow, this time.  It was some moments before he had the new range figured out.

“How far astern of the ‘Zelda’ are we now?” called Jacob Farnum.

“A shade over a half a mile.”

“Whew!  And the race only a third run.”

“In other words,” went on the young captain, “the Rhinds boat is gaining steadily on us at the rate of a quarter of a mile an hour.  Not much, yet enough to win the race beyond any dispute.”