A LETTER!—STRANGE HESITATION.—GLOOMY FOREBODINGS.—JACK DOWN DEEP IN THE DUMPS.—FRESH CONFESSIONS.—WHY HE MISSED THE TRYST.—REMORSE AND REVENGE.—JACK'S VOWS OF VENGEANCE.—A VERY SINGULAR AND UNACCOUNTABLE CHARACTER.—JACK'S GLOOMY MENACES.A FRIENDLY CALL.—PRELIMINARIES OF THE DUEL NEATLY ARRANGED.—A DAMP JOURNEY, AND DEPRESSED SPIRITS.—A SECLUDED SPOT.—DIFFICULTIES WHICH ATTEND A DUEL IN A CANADIAN SPRING.—A MASTERLY DECISION. —DEBATES ABOUT THE NICETIES OF THE CODE OF HONOR.—WHO SHALL HAVE THE FIRST SHOT, STRUGGLE FOR PRECEDENCE.—A VERY SINGULAR AND OBSTINATE DISPUTE.—I SAVE O'HALLORAN FROM DEATH BY RHEUMATISM.CHAPTER XXXI.