To "change" a man is to shift him from one car to another on the plea that the one he is in is to be taken off at a junction. While he is changing and going down the aisle, his "roll" or wallet disappears, and the pickpockets take another train at a junction. It is all done in a flash, and is as simple as can be to those who are in the business, but a great many "leathers" would be saved if people would only be careful and not crowd together like sheep. At circuses I have seen them push and shove like mad, and all the while the pickpockets were at work among them. An interesting story is told of an Illinois town where a mob of pickpockets had been led to believe that they had "squared" things sufficiently with the authorities to be able to run "sure thing" games at the show grounds with impunity,--pickpockets dabble occasionally in games,--but they swindled people so outrageously that the authorities got scared and prohibited the games. The men had paid so heavily for what they had considered were privileges, that they were going to be losers unless they got in their "graft" somehow, so they turned pickpockets again, and, as one man put it, "simply tore the crowd open." When it dispersed, the ground was literally covered with emptied pocketbooks. The easiest way for the police officer to deal with the pickpocket is to know him whenever he appears, and to let him understand that he is "spotted" and would better keep away. Some officers are born thief-catchers, and can seemingly scent crime where it cannot even be seen, and, whether they know a man or not, can pick out the real culprit. The average officer, however, must recognise his man before he can touch him, unless he catches him red-handed, and it is he who knows a great many offenders and can call the "turn" on them, give their names and records, that is the great detective of modern times. The sleuth of fiction, who catches criminals by magic, as it were, is a snare and a delusion. During my police experience I carried with me a pocket "rogue's gallery" of the most notorious pickpockets of the section of the country in which I had to travel. For a time I saw so many of these gentry in the flesh, and was shown so many pictures, that a bewildering composite picture of all formed in my mind. It seemed to me, sometimes, as if everybody I saw in the streets resembled a pickpocket that I had to be on the lookout for. I finally determined to commit to memory a picture a day, or every two or three days as was necessary, and learn to differentiate, and the method proved successful. To-day there are about fifty pickpockets that I shall know wherever I see them. The majority of them I have met personally, but a number are known to me by photograph only.