Of the last category, the man whom I have called the irresponsible criminal, there is not much of interest or value that I have to report. While acting as police officer I practically never encountered him in the open, and the few members of his class that I saw in prisons seemed to me to have become irresponsible largely during their imprisonment. Perhaps I take a wrong view of the matter, but I cannot get over the belief that the majority of offenders, particularly those who are ranked as "professionals," are _compos mentis_ as far as the law need require. In every department of the prisons that I visited, men were to be seen who gave the impression of being at least queer, but they formed but a very small part of the prison population, and may very possibly have been shamming the eccentricities which seemed to indicate that they were on the border line of insanity. For this reason, and, as I say, because I met none in the open, it has seemed fair to put this class last. The foregoing classification is naturally not meant as a scientific description in the sense that the professional criminologist would take up the matter. I have merely tried to explain how the criminal situation in the United States seems to the man whose business it is to keep an official watch over it. I may have overlooked, in my classification, offenders that some of my brother officers would have included, but it stands for the general impression I got of the criminal world while in their company. To attempt to estimate the numerical strength of these classes as a whole would land one in a bewildering bog of guesses. It is only recently that we have made any serious effort to keep a record of offenders shut up in penal institutions, of crimes which have been detected and of offenders who have been punished, and it is a fact well known in police circles that there is a great deal of crime which is never ferreted out. There is consequently very little use in trying to calculate the number of the entire criminal population. The most that I can say in regard to the question is that never before has this population seemed to me to be so large, but I ought to admit that not until my recent experience have I had such an advantageous point of view from which to make observations. CHAPTER II. THE PROFESSIONAL CRIMINAL. In appearance and manner the professional criminal has not changed much in the last decade. I knew him first over ten years ago, when making my earliest studies of tramp life. I saw him again five years ago, while on a short trip in Hoboland, and we have met recently on the railroads; and he looks just about as he did when we first got acquainted.