TWIENTY miles West of Tucson, the "Sunset Express" stopped at a tank to take on water. Besides the aqueous, addition the engine of that famous flyer acquired some other things that were not good for it.

While the fireman was lowering the feeding hose, Bob Tidball, "Shark" Dodson and a quarter-bred Creek Indian called John Big Dog climbed on the engine and showed the engineer three round orifices in pieces of ordnance that the carried. These orifices so impressed the engineer with their possibilities that he raised both hands in a gesture such as accompanies the ejaculation "Do tell!"

At the crisp command of Shark Dodson, who was leader of the attacking force the engineer descended to the ground and uncoupled the engine and tender. Then John Big Dog, perched upon the coal, sportively held two guns upon the engine driver and the fireman, and suggested that they run the engine fifty yards away and there await further orders.

Shark Dodson and Bob Tidball, scorning to put such low-grade ore as the passengers through the mill, struck out for the rich pocket of the express car. They found the messenger serene in the belief that the "Sunset Express" was taking on nothing more stimulating and dangerous than aqua pura. While Bob was knocking this idea out of his head with the butt-end of his six-shooter Shark Dodson was already dosing the express-car safe with dynamite.

The safe exploded to the tune of $30,000, all gold and currency. The passengers thrust their heads casually out of the windows to look for the thunder-cloud. The conductor jerked at the bell-rope, which sagged down loose and unresisting, at his tug. Shark Dodson and Bob Tidball, with their booty in a stout canvas bag, tumbled out of the express car and ran awkwardly in their high-heeled boots to the engine.

The engineer, sullenly angry but wise, ran the engine, according to orders, rapidly away from the inert train. But before this was accomplished the express messenger, recovered from Bob Tidball's persuader to neutrality, jumped out of his car with a Winchester rifle and took a trick in the game. Mr. John Big Dog, sitting on the coal tender, unwittingly made a wrong lead by giving an imitation of a target, and the messenger trumped him. With a ball exactly between his shoulder blades the Creek chevalier of industry rolled off to the ground, thus increasing the share of his comrades in the loot by one-sixth each.

Two miles from the tank the engineer was ordered to stop.

The robbers waved a defiant adieu and plunged down the steep slope into the thick woods that lined the track. Five minutes of crashing through a thicket of chapparal brought them to open woods, where three horses were tied to low-hanging branches. One was waiting for John Big Dog, who would never ride by night or day again. This animal the robbers divested of saddle and bridle and set free. They mounted the other two with the bag across one pommel, and rode fast and with discre- tion through the forest and up a primeval, lonely gorge. Here the animal that bore Bob Tidball slipped on a mossy boulder and broke a foreleg. They shot him through the head at once and sat down to hold a council of flight. Made secure for the present by the tortuous trail they- had travelled, the question of time was no longer so big. Many miles and hours lay between them and the spryest posse that could follow. Shark Dodson's horse, with trailing rope and dropped bridle, panted and cropped thankfully of the grass along the stream in the gorge. Bob Tidball opened the sack, drew out double handfuls of the neat packages of currency and the one sack of gold and chuckled with the glee of a child.

"Say, you old double-decked pirate," he called joyfully to Dodson, "you said we could do it -- you got a head for financing that knocks the horns off of anything in Arizona."

"What are we going to do about a hoss for you, Bob? We ain't got long to wait here. They'll be on our trail before daylight in the mornin'."

"Oh, I guess that cayuse of yourn'll carry double for a while," answered the sanguine Bob. "We'll annex the first animal we come across. By jingoes, we made a haul, didn't we? Accordin' to the marks on this money there's $30,000 -- $15,000 apiece!"

"It's short of what I expected," said Shark Dodson, kicking softly at the packages with the toe of his boot and then he looked pensively at the wet sides of his tired horse.

"Old Bolivar's mighty nigh played out," he said, slowly. "I wish that sorrel of yours hadn't got hurt."

"So do I," said Bob, heartily, "but it can't be helped. Bolivar's got plenty of bottom -- he'll get us both far enough to get fresh mounts. Dang it, Shark, I can't belp thinkin' how funny it is that an Easterner like you can come out here and give us Western fellows cards and spades............