and shanties. Once more Reade had driven off the gamblers, though this
time with less trouble than in Arizona. At Blixton, Tom had merely sent
for the four peace officers in the town of Blixton, and had had the
gamblers warned out of camp. They had gone, but there had been wrathful
mutterings among many of the workmen.

The camp was a half mile back from the water's edge, on a low hillside.
Here the men of the outfit were settled. There had been mutinous
mutterings among some of the men, but so far there had been no open revolt.

Tom, however, who had had considerable experience in such matters, looked
for some form of trouble before the smouldering excitement quieted. So did
Harry.

On this dark night Tom had proposed that he and his chum take a stroll down
to the shore front to see whether all were well there. Soon after leaving
camp behind, the young engineers had started on a jog-trot. Just before
they reached the water's edge the wind had borne to their ears the faint
report of what must have been an explosion out over the waters of the gulf.

"Trouble!" Tom whispered in his chum's ear. "Most likely some of the
rascals that we drove out of camp have been trying to set back our work
with dynamite. If they have done so we'll teach 'em a lesson if we can
catch them!"

So the young engineers had started out over their narrow retaining wall.
We have seen how they had walked most of the distance when Harry had had
his sudden warning of the hostile arm uplifted over his head.

"What could it have been?" demanded Tom in a low voice, as he continued to
cast the light from his flash lamp out over the waters on either side of
the wall.

"It must have been my nervous imagination," admitted Harry. "Whew! But
it _did_ seem mighty real for the moment."

"Then you're inclined, now, to believe that it was purely imagination?"
pursued Tom.

"Ye---e---es, it must have been," assented Harry reluctantly.

Tom made some final casts with the light.

While they were conversing, well past the short radius of the flash lamp's
glare, a massive black head bobbed up and down with the waves. Out there
the huge negro who had swiftly vanished from the wall, and who had swum
under water for a long distance, was indolently treading water. Wholly at
home in the gulf, the man's black head blended with the darkness of the
water and the blackness of the night.

"Oh, then," suggested Reade, "we may as well go along on our way