"Because they are sure that if I were to take them into custody, which I could do, knowing what they are, and present them before a magistrate, they would all be committed to prison for a month, as rogues and vagabonds." "They prefer then to have lost no inconsiderable capital in dress and dinner, to being laid up in jail." "Exactly so." The bell rings, and all five go off into the same carriage to London. This is a circumstance that actually occurred; and a similar one happened when the Queen went to Dublin. The mere appearance of one the Detective officers before a "school" which had transported itself in the Royal train, spoilt their speculation; for they all found it more advantageous to return to England in the same steamer with the officer, than to remain with the certainty of being put in prison for fourteen or twenty-eight days as rogues and vagabonds. So thoroughly well acquainted with these men are the Detective officers we speak of, that they frequently tell what they have been about by the expression of their eyes and their general manner. This process is aptly termed "reckoning them up." Some days ago, two skilful officers, whose personal acquaintance with the swell mob is complete, were walking along the Strand on other business, when they saw two of the best dressed and best mannered of the gang enter a jeweller's shop. They waited till they came out, and, on scrutinising them, were convinced, by a certain conscious look which they betrayed, that they had stolen something. They followed them, and in a few minutes something was passed from one to the other. The officers were convinced, challenged them with the theft, and succeeded in eventually convicting them of stealing two gold eye-glasses, and several jeweled rings. "The eye," said our informant, "is the great detector. We can tell in a crowd what a swell-mobsman is about by the expression of his eye." It is supposed that the number of persons who make a trade of thieving in London is not more than six thousand; of these, nearly two hundred are first-class thieves or swell-mobsmen, six hundred "macemen," and trade swindlers, bill-swindlers, dog-stealers, &c.; About forty burglars, "dancers," "garretteers," and other adepts with the skeleton-keys. The rest are pickpockets, "gonophs--" mostly young thieves who sneak into areas, and rob tills--and other pilferers. To detect and circumvent this fraternity, is the science of thief-taking. Here, it is, however, impossible to give even an imperfect notion of the high amount of skill, intelligence, and knowledge, concentrated in the character of a clever Detective Policeman. We shall therefore finish the sketch in another part. Part XII. A DETECTIVE POLICE PARTY.