The judge of the United States court of the district lying along the Rio Grande border found the following letter one morning in his mail:

JUDGE:
When you sent me up for four years you made a talk. Among other hard things, you called me a rattlesnake. Maybe I am one -- anyhow, you hear me rattling now. One year after I got to the pen, my daughter died of -- well, they said it was poverty and the disgrace together. You've got a daughter, Judge, and I'm going to make you know how it feels to lose one. And I'm going to bite that district attorney that spoke against me. I'm free now, and I guess I've turned to rattlesnake all right. I feel like one. I don't say much, but this is my rattle. Look out when I strike.

Yours respectfully,
RATTLESNAKE.

Judge Derwent threw the letter carelessly aside. It was nothing new to receive such epistles from desperate men whom he had been called upon to judge. He felt no alarm. Later on he showed the letter to Littlefield, the young district attorney, for Littlefield's name was included in the threat, and the judge was punctilious in matters between himself and his fellow men.

Littlefield honoured the rattle of the writer, as far as it concerned himself, with a smile of contempt; but he frowned a little over the reference to the Judge's daughter, for he and Nancy Derwent were to be married in the fall.

Littlefield went to the clerk of the court and looked over the records with him. They decided that the letter might have been sent by Mexico Sam, a half-breed border desperado who had been imprisoned for manslaughter four years before. Then official duties crowded the mat- ter from his mind, and the rattle of the revengeful serpent was forgotten.

Court was in session at Brownsville. Most of the cases to be tried were charges of smuggling, counterfeiting, post-office robberies, and violations of Federal laws along the border. One case was that of a young Mexican, Rafael Ortiz, who had been rounded up by a clever deputy marshal in the act of passing a counterfeit silver dollar. He had been suspected of many such deviations from rectitude, but this was the first time that anything provable had been fixed upon him. Ortiz languished cozily in jail, smoking brown cigarettes and waiting for trial. Kilpatrick, the deputy, brought the counterfeit dollar and handed it to the district attorney in his office in the court-house. The deputy and a reputable druggist were prepared to swear that Ortiz paid for a bottle of medicine with it. The coin was a poor counterfeit, soft, dull-looking, and made principally of lead. It was the day before the morning on which the docket would reach the case of Ortiz, and the district attorney was preparing himself for trial.

"Not much need of having in high-priced experts to prove the coin's queer, is there, Kil?" smiled Littlefield, as he thumped the dollar down upon the table, where it fell with no more ring than would have come from a lump of putty.

"I guess the Greaser's as good as behind the bars," said the deputy, easing up his holsters. "You've got him dead. If it had been just one time, these Mexicans can't tell good money from bad; but this little yaller rascal belongs to a gang of counterfeiters, I know. This is the first time I've been able to catch him doing the trick. He's got a girl down there in them Mexican jacals on the river bank. I seen her one day when I was watching him. She's as pretty as a red heifer in a flower bed."

Littlefield shoved the counterfeit dollar into his pocket, and slipped his memoranda of the case into an envelope. Just then a bright, winsome face, as frank and jolly as a boy's, appeared in the doorway, and in walked Nancy Derwent.

"Oh, Bob, didn't court adjourn at twelve to-day until to-morrow?" she asked of Littlefield.

"It did," said the district attorney, "and I'm very glad of it. I've got a lot of rulings to look up, and -- "

"Now, that's just like you. I wonder you and father don't turn to law books or rulings or something! I want you to take me out plover-shooting this afternoon. Long Prairie is just alive with them. Don't say no, please! I want to try my new twelve-bore hammerless. I've sent to the livery stable to engage Fly and Bess for the buckboard; they stand fire so nicely. I was sure you would go."

They were to be married in the fall. The glamour was at its height. The plovers won the day -- or, rather, the afternoon -- over the calf-bound authorities. Littlefield began to put his papers away.

There was a knock at the door. Kilpatrick answered it. A beautiful, dark-eyed girl with a skin tinged with the faintest lemon colour walked into the room. A black shawl was thrown over her head and wound once around her neck.

She began to talk in Spanish, a voluble, mournful stream of melancholy music. Littlefield did not under- stand Spanish. The deputy did, and he translated her talk by portions, at intervals holding up his hand to check the flow of her words.

"She came to see you, Mr. Littlefield. Her name's Joya Treviñas. She wants to see you about -- well, she's mixed up with that Rafael Ortiz. She's his -- she's his girl. She says he's innocent. She says she made the money and got him to pass it. Don't you believe her, Mr. Little-field. That's the way with these Mexi- can girls; they'll lie, steal, or kill for a fellow when they get stuck on him. Never trust a woman that's in love!"

"Mr. Kilpatrick!"

Nancy Derwent's indignant exclamation caused the deputy to flounder for a moment in attempting to explain that he had misquoted his own sentiments, and then he event on with the translation:

"She says she's willing to take his place in the jail if you'll let him out. She says she was down sick with the fever, and the doctor said she'd die if she didn't have medicine. That's why he passed the lead dollar on the drug store. She says it saved her life. This Rafal. seems to be her honey, all right; there's a lot of stuff in her talk about love and such things that you don't want to hear."

It was an old story to the district attorney.

"Tell her," said he, "that I can do nothing. The case comes up in the morning, and he will have to make his fight before the court."

Nancy Derwent was not so hardened. She was look- ing with sympathetic interest at Joya Treviñas and at Littlefield alternately. The deputy repeated the dis- trict attorney's words to the girl. She spoke a sentence or two in a low voice, pulled her shawl closely about her face, and left the room.

"What did she say then?" asked the district attorney.

"Nothing special," said the deputy. "She said: 'If the life of the one' -- let's see how it went -- 'Si la vida de ella a quien tu amas -- if the life of the girl you love is ever in danger, remember Rafael Ortiz.'"

Kilpatrick strolled out through the corridor in the direction of the marshal's office.

"Can't you do anything for them, Bob?" asked Nancy. "It's such a little thing -- just one counterfeit dollar -- to ruin the happiness of two lives! She was in danger of death, and he did it to save her. Doesn't the law know the feeling of pity?"

"It hasn't a place in jurisprudence, Nan," said Little- field, "especially in re the district attorney's duty. I'll promise you that the prosecution will not be vindictive; but the man is as good as convicted when the case is called. Witnesses will swear to his passing the bad dollar which I have in my pocket at this moment as 'Exhibit A.' There are no Mexicans on the jury, and it will vote Mr. Greaser guilty without leaving the box."

The plover-shooting was fine that afternoon, and in the excitement of the sport the case of Rafael and the grief of Joya Treviñas was forgotten. The district attor- ney and Nancy Derwent drove out from the town three miles along a smooth, grassy road, and then struck across a rolling prairie toward a heavy line of timber on Piedra Creek. Beyond this creek lay Long Prairie, the favourite haunt of the plover. As they were nearing the creek they heard the galloping of a horse to their right, and saw a man with black hair and a swarthy face riding toward the woods at a tangent, as if he had come up behind them.

"I've seen that fellow somewhere," said Littlefield, who had a memory for faces, "but I can't exactly place him. Some ranchman, I suppose, taking a short cut home."

They spent an hour on Long Prairie, shooting from the buckboard. Nancy Derwent, an active, outdoor Western girl, was pleased with her twelve-bore. She had bagged within two brace of her companion's score.

They started homeward at a gentle trot. When within a hundred yards of Piedra Creek a man rode out of the timber directly toward them.

"It looks like the man we saw coming over," remarked Miss Derwent.

As the distance between them lessened, the district attorney suddenly pulled up his team sharply, with his eyes fixed upon the advancing horseman. That individ- ual had drawn a Winchester from its scabbard on his saddle and thrown it over his arm.

"Now I know you, Mexico Sam!" muttered Littlefield to himself. "It was you who shook your rattles in that gentle epistle."

Mexico Sam did not leave things long in doubt. He had a nice eye in all matters relating to firearms, so when he was within good rifle range, but outside of danger from No. 8 shot, he threw up his Winchester and opened fire upon the occupants of the buckboard.

The first shot cracked the back of the seat within the two-inch space between the shoulders of Littlefield and Miss Derwent. The next went through the dashboard and Littlefield's trouser leg.

The district attorney hustled Nancy out of the buck- board to the ground. She was a little pale, but asked no questions. She had the frontier instinct that accepts conditions in an emergency without superfluous argument. They kept their guns in hand, and Littlefield hastily gathered some handfuls of cartridges from the pasteboard box on the seat and crowded them into his pockets

"Keep behind the horses, Nan," he commanded. "That fellow is a ruffian I sent to prison once. He's trying to get even. He knows our shot won't hurt him at that distance."

"All right, Bob," said Nancy steadily. "I'm not afraid. But you come close, too. Whoa, Bess; stand still, now!"

She stroked Bess's mane. Littlefield stood with his gun ready, praying that the desperado would come within range.

But Mexico Sam was playing his vendetta along safe lines. He was a bird of different feather from the plover. His accurate eye drew an imaginary line of circumference around the area of danger from bird-shot, and upon this line lie rode. His horse wheeled to the right, and as his victims rounded to the safe side of their equine breast- work he sent a ball through the district attorney's hat. Once he miscalculated in making a détour, and over- stepped Ms margin. Littlefield's gun flashed, and Mexico Sam ducked his head to the harmless patter of the shot. A few of them stung his horse, which pranced promptly back to the safety line.

The desperado fired again. A little cry came from Nancy Derwent. Littlefield whirled, with blazing eyes, and saw the blood trickling down her cheek.

"I'm not hurt, Bob -- only a splinter struck me. I think he hit one of the wheel-spokes."

"Lord!" groaned Littlefield. "If I only had a charge of buckshot!"

The ruffian got his horse still, and took careful aim. Fly gave a snort and fell in the harness, struck in the neck. Bess, now disabused of the idea that plover were being fired at, broke her traces and galloped wildly away -- Mexican Sam sent a ball neatly through the fulness of Nancy Derwent's shooting jacket.

"Lie down -- lie down!" snapped Littlefield. "close to the horse -- flat on the ground -- so." He almost threw her upon the grass against the back of the recum- bent Fly. Oddly enough, at that moment the words of the Mexican girl returned to his mind:

"If the life of the girl you love is ever in danger, remem- ber Rafael Ortiz."

Littlefield uttered an exclamation.

"Open fire on him, Nan, across the horse's back. Fire as fast as you can! You can't hurt him, but keep him dodging shot for one minute while I try to work a little scheme."

Nancy gave a quick glance at Littlefield, and saw him take out his pocket-knife and open it. Then she turned her face to obey orders, keeping up a rapid fire at the enemy.

Mexico Sam waited patiently until this innocuous fusillade ceased. He had plenty of time, and he did not care to risk the chance of a bird-shot in his eye when could be avoided by a little caution. He pulled his heavy Stetson low down over his face until the shots ceased.

Then he drew a little nearer, and fired with careful aim at what he could see of his victims above the fallen horse. Neither of them moved. He urged his horse a few steps nearer. He saw the district attorney rise to one knee and deliberately level his shotgun. He pulled his hat down and awaited the harmless rattle of the tiny pellets.

The shotgun blazed with a heavy report. Mexico Sam sighed, turned limp all over, and slowly fell from his horse -- a dead rattlesnake.

At ten o'clock the next morning court opened, and the case of the United States versus Rafael Ortiz was called. The district attorney, with his arm in a sling, rose and addressed the court.

"May it please your honour," he said, "I desire to enter a nolle pros. in this case. Even though the defend- ant should be guilty, there is not sufficient evidence in the hands of the government to secure a conviction. The piece of counterfeit coin upon the identity of which the case was built is not now available as evidence. I ask, therefore, that the case be stricken off."

At the noon recess Kilpatrick strolled into the district attorney's office.

"I've just been down to take a squint at old Mexico Sam," said the deputy. "They've got him laid out. Old Mexico was a tough outfit, I reckon. The boys was wonderin' down there what you shot him with. Some said it must have been nails. I never see a gun carry anything to make holes like he had."

"I shot him," said the district attorney, "with Exhibit A of your counterfeiting case. Lucky thing for me -- and somebody else -- that it was as bad money as it was! It sliced up into slugs very nicely. Say, Kil, can't you go down to the jacals and find where that Mexican girl lives? Miss Derwent wants to know."