better slip into
our clothing. Maybe somebody is-- Listen!"

Dave broke off short, and both strained their ears to hear what was
taking place outside. They heard a confused shouting, followed by
several yells. And then came a volley of shots--five or six in
number.

"It's an attack! That's what it is!" cried the senator's son. "I'll
bet some of those Mexican bandits are coming over here! Oh, Dave! what
do you suppose we had better do?"

"I don't know, except that we had better slip on our clothing and get
our pistols," answered Dave. "This looks as if it might be serious."

"Up, boys! Up!" came the cry from somebody outside. "Get your guns and
your pistols! The Mexican raiders are coming this way!"

CHAPTER XXV

THE MEXICAN RAIDERS

By the time the two chums had hastily donned their clothing and
possessed themselves of the pistols they had purchased in San Antonio
on the advice of Mr. Watson, the camp was in confusion from end to
end, with the various bosses shouting orders and the men themselves
wanting to know what the trouble was and what they had better do.

"It's some of those confounded greasers!" cried Frank Andrews, as he,
too, arose and armed himself. He had a repeating rifle, and it was
known to Dave and Roger that he was an exceptionally good shot.

Andrews led the way from the building, followed by our hero and Roger
and several others. In the meantime, the distant shouting and shooting
seemed to have moved farther westward, in the direction where the new
Catalco bridge was being constructed.

"It can't be their intention to blow up the bridge?" queried Roger.
There had been talk of this several times.

"No telling what those rascals are up to," answered Frank Andrews.
"This may be only a rumpus kicked up to cover a cattle raid or
something like that."

In the midst of the excitement the telephone in the main office began
to ring and was answered by one of the clerks. A few minutes later he
came rushing out to where Mr. Obray stood talking to his assistant and
the boss of the construction camp.

"Just got a telephone from the Tolman ranch," announced the clerk.
"Old man Tolman said they had been raided and that half of the raiders
were coming this way. I tried to get some details from him, but in the
midst of the talk I was shut off. I suppose somebody cut the wire."

"I thought that might be it," answered the head of the engineering
corps.

"We ought to help Tolman all we can,"