This Sat.u.r.day night Alex and Jack, borrowing Winchesters from other members of the telegraph-car party, had set out for a "couple of good rugs," as they put it, and on leaving the train had headed east, toward the aqueduct, in which direction they had heard barks of the midnight prowlers.

They had gone perhaps three miles, and had fired on several of the wily animals, without success, when suddenly Jack caught Alex by the arm and pointed away to the east.

"Look, Al! What's that?"

"Why, it looks like--It is! It's a signal light!

"And calling us--KX!" cried Alex. "Something must be wrong with Wilson!"

"What'll we do? Back to the train?"

"Have you a match and some paper?" said Alex, going hurriedly through his own pockets.

"Some matches."

"Here's a couple of letters. Come on back to the rails, find some chips, and make a fire. See if we can't answer him, and learn what the trouble is."

They were already racing for the track, reached it, and quickly gathering together a little pile of dry bark and chips knocked from the ties, made a fire at the track-side, and lit it.

As the flames burst up Alex threw off his coat, and using it as a curtain, raised and lowered it in a flashed "I, I, KX!"

The call twinkled on. Wilson had not seen it. But the next moment, before Alex had completed a second answer, the red light disappeared. Alex again shot forth the gleaming "I, I, KX!" and in blinking response they read:

"Chased out of station. Two men. Wire cut. Something wrong. Help!--V."

"OK. But we are three miles from the train. Hunting. Will we come, or go back for help?" signalled Alex.

There was a pause, and the red light blinked, "Come! Quick!"

"OK. Coming." Only pausing to stamp out the fire, the two boys were away at a run, heading directly for the light, which at intervals Wilson continued to show, as a guide.

Their open-air experience of a month had put the two boys in the best of condition, and keeping on at a smart pace, within half an hour the light showed just ahead, and a few minutes after Wilson ran forward to greet them.

"I don't know what's in the air, but certainly something," he announced.

"As you fellows are armed too, suppose we go back and get the two men in the station car, and see if we can't make them tell?" he suggested.

"Lead ahead," agreed the others.

Stealthily they made their way amid the intervening cars, and emerged opposite the little depot.

In the window was the shadow of a man smoking.

They stole across to the door, and Wilson, leading, cautiously glanced within. He turned and held up one finger. Revolver in hand, he tiptoed up the steps, and with a cry sprang inside and toward the man in the chair.

The intruder was so taken by surprise that he tumbled over backward. In a jiffy the three boys were upon him, and had pinned him to the floor; and while Alex closely clutched his mouth, to prevent him calling out, the others speedily bound his hands and feet with some convenient pieces of wire.

Satisfied that their prisoner was firmly secured, and having removed his pistol and cartridge-belt, the boys replaced him in the chair, and Wilson, pointing his revolver at the man's head, demanded, "Where is your pard? And what are you and he up to?"

There was a look of amus.e.m.e.nt in the man's face as Alex removed his hand, and he replied, "Nothin' doin', boys. You'll have to guess."

"I'll give you three, to tell," said Wilson, a.s.suming a fierce expression and beginning to count.

The prisoner laughed outright. "You gentleman kids wouldn't shoot a fly,"

he declared coolly.

Wilson colored with mortification. For of course he had had no intention of shooting. Even Alex and Jack were forced to smile at the turn of the situation. Wilson had his revenge, however. "Gag him, then, Al," he suggested, "and we will stow him away beneath the car."

The man's mouth opened for a shout. In a flash Alex had slapped a handkerchief between his teeth, and despite the man's struggles stuffed it well in. Then, taking from his neck a long colored neckerchief, he bound it twice about the man's face.

"Now out with him, this side," said Wilson, opening the rear door.

"Wouldn't it be better to take him over under one of the cars on the sidings?" Jack suggested. "His pard might return, and he kick, or make some kind of a noise underneath."

"That's so." Dragging their prisoner forth, they glanced up and down to see that no one was in sight, and with Jack at his feet and Alex and Wilson at his arms, they hastened across the rails, pa.s.sed between two freight-cars, and in the deep shadow beyond placed him on the ground and bound him firmly to a rail.

"Be sure you don't talk now," said Wilson derisively as they turned away.

"What next?" Jack asked.

"It's pretty sure to be some mischief about the bridge. Let's have a look around there," suggested Alex.

Approaching the brink of the ravine at a point some distance from the viaduct, the boys glanced below. From the three broke a simultaneous low cry of understanding and indignation.

In the light of several lanterns a party of seemingly fifteen or twenty men were piling brush about the base of one of the central wooden piers.

"The K. & Z. people again, sure as you're born!" exclaimed Alex hotly.

"And after their solemn agreement!"

"If they succeed in burning it, they will hold back our supplies two or three weeks, and reach the pa.s.s ahead of us, dead certain," added Jack through his teeth. "We've got to stop them, boys!"

"Isn't there a hand-car or a velocipede here, Wilse?" Alex inquired.

"No. Not even a push-car. And it'd take one of us an hour and a half to reach the construction-train."

"But that's certainly the only thing to be done," Jack pointed out.

"Perhaps two of us, with the rifles, could hold them--"

A flicker of light broke out below which was not a lantern, and approached the dimly disclosed brush-pile. Quick as a flash Jack's rifle went to his shoulder, and there was a reverberating crash. The light disappeared and there came up a chorus of surprised shouts and the clatter of running feet.

"Now we are in for it. I think we had better stick it out together," said Alex quietly. "Perhaps the firing will be heard at the train."

The others agreed, and at Wilson's suggestion they made their way a few feet down the slope to a ledge from which the whole structure of the bridge could dimly be seen.

"How are you fellows off for ammunition?" whispered Wilson.

"I have four more rounds in the rifle, and thirty in my belt," said Jack.

"Five in the gun and twenty-seven in the belt," Alex announced.