The theft was, however, quickly discovered, and the French police were put on the alert. Shaw immediately betrayed himself by addressing an anonymous letter to a royal personage in London, in which the writer offered to restore to their rightful owners, the English royal family, certain jewels wrongfully detained by the Duke of Brunswick, on receiving a reward of 100,000 francs. This letter was at once handed over to the authorities in Scotland Yard, who passed it on to Paris. A postscript was added to the letter, stating that the writer would meet any messenger sent with the money at Boulogne. Acting at once on this clue, the French detectives hastened to Boulogne, and, visiting every hotel, soon found a young man answering the description, who was arrested and taken back to Paris. The diamonds were found in his possession. This Shaw, a tall, very thin young man, with a pale, intelligent face, and very bold, prominent eyes, was soon recognised by the police as a professional thief of English extraction, who had worked much abroad, and was indeed a cosmopolitan rogue, having committed many great robberies in the capitals of Europe, generally by the same means. He was sentenced to twenty years (_travaux forcés_), although the Duke, dreading the publicity of the Assize court, would not appear to prosecute. The prison known as La Santé was situated in the rue de la Santé close to the Boulevard Arago, upon the left bank of the Seine. Founded and completed in the palmiest days of the French Empire, it was the newest and certainly long the best prison in Paris. Enthusiastic Frenchmen have, indeed, declared that it was the best and most beautiful building of the kind in Europe, but the statement is rather far-fetched. Coming twenty years later than Mazas, it was a marked advance upon that penitentiary, which it resembled in many respects. It consisted of two distinct divisions, or “sides,” and the inmates of each were subjected to different systems of imprisonment. In one, unbroken cellular confinement was the rule, in the other, prisoners occupied separate sleeping cells at night, but took their food and exercise, and worked together during the day. The former régime was applied to all sentenced for the first time, the latter to _récidivistes_, or habitual offenders, who fell into trouble again and again. The cellular division, that first reached when the threshold of the prison, with its sleepy gatekeepers and punctilious _greffier_, was passed, was cleaner and tidier than Mazas as I saw it, and altogether better kept. There were the same radiating wings, extending like the spokes of a wheel round a central nave, the _rond point_; in which was the same glass house or observatory, with an altar on top, towards which all the cell doors, as to their Mecca, religiously turned for the Mass. The cells were warmed and ventilated by an arrangement of hot water pipes and fresh air flues, just as is seen in every modern prison since