About five o'clock on the afternoon of Saturday, the 12th September 1840, a person named Daun, a miller, together with his wife and son, observed from the stage of their mill, on Wimbledon Common, two carriages approaching it from opposite directions, and at once suspected what was about to take place. Two gentlemen first quitted the carriages--each with a pistol-case--duly loaded a brace of pistols, and stepped out twelve paces; on which two other gentlemen, the Earl of Cardigan and Captain Tuckett, came up, and took their stations at the points indicated. To each was given a pistol; the other two withdrew to a little distance; the word to fire was uttered, and immediately followed by an ineffectual discharge of both pistols. The principals remained at their posts; a second brace of pistols was given them; again both fired and Captain Tuckett fell, wounded in the small of the back--bleeding profusely, but, as it proved, not from a mortal, or even dangerous wound. Thus the aristocratic affair of _honour_ was more fortunate in its issue than that plebeian one in which, two or three years before, the young linendraper Mirfin had received his mortal "satisfaction." Lord Cardigan's second was Captain Douglas, and Captain Wainwright was that of Captain Tuckett. The whole affair of the duel had been witnessed by the miller, (who was also a constable,) and his wife and son, standing on the stage of the windmill. The moment that Captain Tuckett fell, the miller and his son quitted their post of observation, ran up to the scene of action, and intimated to all the parties that they must consider themselves in his custody. Lord Cardigan still held in his right hand the pistol with which he had fired; and there lay on the ground two pistol-cases, one of them bearing the Earl's coronet. Captain Tuckett lay on the ground, his second Captain Wainwright kneeling beside him, supporting him; while Sir James Anderson, a surgeon, who had attended them to the field, was examining the wound. One of these three entreated the constable to allow the wounded gentleman to be removed to his own house, giving a solemn pledge that, on his recovery, he should attend before the magistrate. At the same time one of them took out a card, on which was printed--"Captain Harvey Tuckett, No. 13 Hamilton Place, New Road," and wrote in pencil, on the back of the card, the words, "Captain H. Wainwright." Who gave this card remains, in the evidence, a mystery; nor did it appear whether Lord Cardigan saw the card given, or knew what was printed or written on it, or heard what was said. As almost the whole interest of the trial, and also its unexpected issue, turned upon the identity of the wounded duellist, and the requisite adroitness and vigilance of the late Sir William Follett, the Earl's counsel, in dealing with this card, and the circumstances attending its delivery to the constable, the reader will find his account in remarking these circumstances accurately.