It is now more than a decade since I became acquainted with tramps. My purpose in seeking them out was to learn about their life; and I soon saw that, to know it well, I must become joined to it and be part and parcel of its various manifestations. At different times during this period,--some of them lengthening out into months,--I have lived intimately with the vagabonds of both England and the United States. In the tramp class, or so near it that the separation is almost imperceptible, are to be found any number of criminals associating freely, either for purposes of business or sociability, with their less ambitious brethren. In nearly every large city of the two countries mentioned I know something about them, and in not a few instances I have succeeded in becoming well acquainted with notorious members of their class. My desire is to tell of the impression they make on one who studies them in their own habitat, that I may be able to show how different is the outdoor criminal from his convicted brother shut in behind prison-bars. I I must first note the species of criminal that I have met in the open. Lombroso and other investigators classify the cases they have studied as political, instinctive, occasional, habitual, and professional; but, so far as my finding is concerned, only one class is of any great importance--the professional. That there are also instinctive criminals, as well as occasional, I am well aware; but they form a very small part of that outcast world that I know best, and cannot be taken as definitely representative of it. It is the man who wilfully and knowingly makes a business of crime or is experimenting with it from commercial motives that I have found in largest numbers "on the road"; and it is he, I believe, who appears oftenest in our criminal courts. To be sure, he tries to make out that he is not a wilful offender, and often succeeds in convincing a jury that he is not; but this is due to his cleverness and trained abilities.