Concerning a subject so changeable as cant and slang, it is evidently of importance to know the acceptation of every expression at every period of the development of the language. As a matter of course, therefore, I have tried to discover, in the language of our author, the exact shade of sense of the different slang and cant-expressions, especially in cases where it does not coincide with the common usage, or where it concerns rare expressions. In order to contribute to the knowledge of the prevalence of the cant and slang-expressions, I have tried to indicate the social position, the sex, the degree of culture, etc., of the persons speaking; and, as far as possible, I have ascertained the history and etymology of my expressions, though, in this respect, my efforts have often been without success. A rather difficult point has been the classification of the expressions. The question whether a term may be regarded as vulgar or slang, or merely colloquial, is, in many cases, very debateable, as the opinions even of qualified judges concerning this matter are often divergent. In such cases, I have endeavoured to find a medium, founding my statements on the authority of cultivated Englishmen. A number of original cant and slang-expressions have, _to a certain degree_, penetrated into the colloquial speech of the cultivated, holding thus an intermediate position between cant or slang on one side, and colloquial language on the other: these terms have been treated as special groups _vulgar_ > _colloquial_ and _slang_ > _colloquial_. I take the opportunity to express my sincere thanks to the University-Lecturer, Mr. CHARLES SCOTT FEARENSIDE, whose valuable assistance has been of great use to me throughout the course of my researches. I also beg to express my gratitude to Mr. SIDNEY CHARLESTON, University-Lecturer in Upsala, and to Mrs. GERTRUDE FAHLSTRÖM, née PICKERING. Lund, October 6th, 1910. _Olof Bosson._ Bibliography. In the following list of Jerome’s books, T. E. means «Tauchnitz Edition», E. L. «The English Library».