Perhaps a detective pays a visit to F.'s wife. With the remembrance of many kindly acts performed by the police during her husband's involuntary absences, she is torn between a stubborn loyalty to him and her wish to be civil to her visitor. He is sympathetic--cynics may not believe that the sympathy is often genuine--but he has his duty to do. He does not expect her consciously to betray her husband, but his eyes are busy while he puts artless questions. An incautious word, the evasion of a question may give him the hint he seeks, or, on the other hand, she may be too alert and his mission may be fruitless. Meanwhile a description and photograph of F. have been circulated by what may be called the publicity department of Scotland Yard. It may be even given to the newspapers, for your modern detective realises the advantage of deft use of the Press. Remember, F. is a known criminal, and even in so vast a place as London no man who is known can hide himself indefinitely. A striking personal instance may be cited. The writer, in the course of an aimless walk through obscure streets, accompanied by a well-known detective, was greeted by no fewer than eight officers. I believe there is no instance on record of a definite person being "wanted" where the police have failed to find him. He may have escaped arrest for lack of evidence, but he has been found. The wide-flung net will, sooner or later, enmesh F. He may be seen and recognised or, what is more likely, he will be betrayed by one of his associates. It does not follow that he will at once be arrested and charged. He may be merely "detained," which means that the police have him in custody for not more than twenty-four hours, at the end of which time he must either be brought before a magistrate or set at liberty. He must not be questioned, but he is given to understand why he is held, and may, if he likes, volunteer a statement. If any of the stolen property is found on him the matter at once becomes straightforward, and if he is believed to have hidden or disposed of it to any particular person search warrants are procured to bring it to light. Another instance of the methods employed by the C.I.D. to establish identity may be recalled. Two Americans in Frankfort tried to rob a man of L30,000. One was arrested, and the other got away. The C.I.D. was asked if it could make any suggestions to the Frankfort police. Very courteously, Scotland Yard said in effect: "Yes. If the man left in a hurry, he probably left something behind. Go to his hotel and see." Frankfort did so, found some luggage in the cloakroom, and among them shirts with the name of a London maker. A Scotland Yard detective went to the address, and found the name of a certain American "crook" as having his shirts made to measure there. When the man, all unconscious that his connection with the robbery was known, stepped out of the train at Charing Cross Station a few hours later he was arrested.