Here, too, Dumas' account of the "question by water," or, rather, the notes on the subject, which accompanied the first (1839) edition of "Les Crimes Célèbres," form interesting, if rather horrible, reading. Not alone in the Bastille was this horrible torture practised, but in most of the prisons of the time. "_Pour la 'question ordinaire,' quatre coquemars pleins d'eau, et contenant chacun deux pintes et demi, et pour 'la question extraordinaire' huit de même grandeur._" This was poured into the victim through a funnel, which entered the mouth, and sooner or later drowned or stifled him or her, or induced confession. The final act and end of the unnatural Marquise de Brinvilliers took place at the Place de la Grève, which before and since was the truly celebrated place of many noted crimes, though in this case it was justice that was meted out. As a sort of sequel to "The Conspirators," Dumas adds "A Postscriptum," wherein is recounted the arrest of Richelieu, as foreordained by Mlle. de Valois. He was incarcerated in the Bastille; but his captivity was but a new triumph for the crafty churchman. "It was reported that the handsome prisoner had obtained permission to walk on the terrace of the Bastille. The Rue St. Antoine was filled with most elegant carriages, and became, in twenty-four hours, the fashionable promenade. The regent--who declared that he had proofs of the treason of M. de Richelieu, sufficient to lose him four heads if he had them--would not, however, risk his popularity with the fair sex by keeping him long in prison. Richelieu, again at liberty, after a captivity of three months, was more brilliant and more sought after than ever; but the closet had been walled up, and Mlle. de Valois became Duchesse de Modena." Not only in the "Vicomte de Bragelonne" and "The Taking of the Bastille" does Dumas make mention of "The Man in the Iron Mask," but, to still greater length, in the supplementary volume, called in the English translations "The Man in the Iron Mask," though why it is difficult to see, since it is but the second volume of "The Vicomte de Bragelonne." This historical mystery has provided penmen of all calibres with an everlasting motive for argumentative conjecture, but Dumas without hesitancy comes out strongly for "a prince of the royal blood," probably the brother of Louis XIV. It has been said that Voltaire invented "the Man in the Iron Mask."