This is, in brief, the history of the famous Lyons murders. It must be added that many experiments were made with Aymar in Paris, and that they were all failures. He fell into every trap that was set for him; detected thieves who were innocent, failed to detect the guilty, and invented absurd excuses; alleging, for example, that the rod would not indicate a murderer who had confessed, or who was drunk when he committed his crime. These excuses seem to annihilate the wild contemporary theory of Chauvin and others, that the body of a murderer naturally exhales an invisible _matière meurtrière_--peculiar indestructible atoms, which may be detected by the expert with the rod. Something like the same theory, we believe, has been used to explain the pretended phenomena of haunted houses. But the wildest philosophical credulity is staggered by a _matière meurtrière_ which is disengaged by the body of a sober, but not by that of an intoxicated, murderer, which survives tempests in the air, and endures for many years, but is dissipated the moment the murderer confesses. Believers in Aymar have conjectured that his real powers were destroyed by the excitements of Paris, and that he took to imposture; but this is an effort of too easy good-nature. When Vallemont defended Aymar (1693) in the book called _La Physique Occulte_, he declared that Aymar was physically affected to an unpleasant extent by _matière meurtrière_, but was not thus agitated when he used the rod to discover minerals. We have seen that, if modern evidence can be trusted, holders of the rod are occasionally much agitated even when they are only in search of wells. The story gave rise to a prolonged controversy, and the case remains a judicial puzzle, but little elucidated by the confession of the hunchback, who may have been insane, or morbid, or vexed by constant questioning till he was weary of his life. He was only nineteen years of age.