yards to the good in the lead.

"I'm afraid," muttered Hal, rejoining Benson, "that I'll simply have to go
below."

"I'm afraid so," nodded Jack. "We simply can't afford to lose this or any
other race to the 'Pollard.'"

"Williamson knows that fully as well as we do, though," Hal Hastings went
on. "And Williamson--"

Of a sudden Hal stopped short. He half staggered, clutching at a rail,
while his eyes stared and his lips twitched.

"Why--why--there's Williamson--aft on the deck!" muttered Hastings.

"What!"

Jack, too, wheeled like a flash. Back there in a crowd of cadets stood the
machinist upon whom the submarine boys were depending for the best showing
that the "Farnum" could make.

"Williamson up here!" gasped Hal. "And--"

"That fellow, Truax, all alone with the motors!" hissed Captain Jack.
Then, after a second or two of startled silence:

"Come on, Hal!"

The naval cadets were too much absorbed in watching the race to have
overheard anything. Williamson, too, standing at the rail, looking out
over the water, had not yet discovered that Hal Hastings was up from the
engine room.

Jack Benson stole below on tip-toe, though with the machinery running so
much stealth was not necessary. Right behind him followed Hal.

As the two gained the doorway of the engine room Sam Truax had his back
turned to them, and so did not note the sudden watchers.

There was a smile of malicious triumph on Truax's face as he turned a
lever a little way over, thus decreasing the ignition power of the motors.

Both Jack and Hal could see that the gasoline flow had been turned on
nearly to the full capacity. It was the poor ignition work that was making
the motors respond so badly. A little less, and a little less, of the
electric spark that burned the gasoline and air mixture--that was the
secret of the gradually decreasing speed, while all the time it looked as
though the "Farnum" was doing her level best to win the race.

Whistling, as he bent over, Sam Truax caught up a long, slender steel bar.
With this he stepped forward, intent upon his next wicked step.

"Gracious! The scoundrel is going to run that bar in between the moving
parts of the engine and bring about a break-down!" quivered Hal.

Sam Truax stood watching for his chance to thrust the steel bar in just
where it would inflict the most damage. Then raising the bar quickly, he
poised for the blow.

"Stop that, you infernal sneak!" roared Jack Benson, boun