As Colwyn moved about the room, examining everything with his quick appraising eye, he noticed that the position of the bed had been changed since he last saw it. The head was a trifle askew, and nearer to the side of the wall than the foot. The difference was slight, but Colwyn could see a portion of the fireplace which had not been visible before. The bed stood almost in the centre of the room, the foot in line with the door, and the head about three or four feet from the chimney-piece. In noting this rather unusual position during his last visit, Colwyn had formed the conclusion that it had been chosen for the benefit of fresh air and light during the summer months, as the window, which looked over the terraced gardens, was nearer that end of the room.
Colwyn approached the head of the bed and bent down to examine the bedposts. A slight groove in the deep pile carpet showed clearly enough that the bed had been pushed back a few inches. The change in position was so trifling that it might have been attributed to the act of a servant in sweeping the room if a closer examination had not revealed the continuance of the groove under the bed. The inference was unmistakable: the bed, in the first instance, had been pushed much farther back on its castors, and then almost, but not quite, restored to its original position.
Had the bed been moved to gain access to the fireplace? He could see no reason for such a proceeding. It was too early in the autumn to need fires, and the room had not been occupied since the murder. In any case, the appearance of the grate showed that no fire had been lit. There was ample space to pass between the head of the bed and the fireplace, though perhaps not much room for movement. On his last visit Colwyn had looked into this space to test its possibilities of concealment. In the quickened interest of his new discovery he pushed the bed out of the way and examined it again.
The first thing that caught his eye was a scratch on the polished surface of the register grate. It looked to be of recent origin, and for that reason suggested to Colwyn's mind that the bed had been moved by somebody who wanted more room in front of the grate. For what purpose? He turned his attention to the grate itself in the hope of obtaining an answer to that question.
The grate was empty, and in the housewifely way a sheet of white paper had been laid on the bottom bars to catch occasional flakes of soot from the chimney. But there were no burnt papers or charred fragments to suggest that the grate had recently been used. Dissatisfied and perplexed, Colwyn was about to rise to his feet when it chanced that his eyes, glancing into a corner, lighted on something tiny and metallic in the crevice between the white paper and the side bars of the grate. Wondering what it was, he succeeded in getting it out with his finger and thumb. It was a percussion cap.
This discovery, strange as it was, seemed at first sight far enough removed from the circumstances of the murder, except so far as it brought the thought of lethal weapons to the imagination. But a weapon which required a percussion cap for its discharge had nothing to do with Violet Heredith's death. She had been killed by a bullet which fitted Nepcote's revolver, which was a pinfire weapon. The medical evidence had established that fact beyond the shadow of a doubt. Moreover, the percussion cap was unexploded, which seemed to make its presence in the grate even more difficult of explanation. It looked as though it had been dropped accidentally, but how came it to be there at all? The strangeness of the discovery was intensified by the knowledge that percussion caps and muzzle-loading weapons had become antiquated with the advent of the breech-loader. Who used such things nowadays?
By the prompting of that mysterious association of ideas which is called memory, Colwyn was reminded of his earlier visit to the gun-room downstairs, and Musard's statement about the famous pair of pistols in the brass-bound mahogany box, which "carried as true as a rifle up to fifty yards, but had a heavy recoil." They belonged to the period between breech-loaders and the ancient flint-locks, and were probably muzzle-loaders. With that sudden recollection, Colwyn also recalled that Musard had been unable to show him the pistols because the key of the case had been mislaid or lost.
This incident, insignificant as it had appeared at the time, seemed hardly to gain in importance when considered in conjunction with the discovery of the cap in the grate. Apart from the stimulus to memory the percussion cap had produced, there was no visible co-ordination between the two facts, because it was, apparently, quite certain that Mrs. Heredith had been shot by Nepcote's revolver, and by no other weapon. But the balance of probabilities in crime are sometimes turned by apparently irrelevant trifles which assume importance on investigation. Was it possible that the key of the pistol-case had been deliberately concealed because the box had something to hide which formed a connection between the pistols and the presence of the cap in the grate? That inference could only be tested by an examination of the case of pistols. The experiment was undoubtedly worth trying. Colwyn left the room and descended the stairs.