THE study of classification is a necessary preliminary to the preparation of a comprehensive guide to recorded information. Of the multifarious systems that have been suggested for the classification of literature, Dewey's “Decimal Classification and Relative Index,“ first developed in 1873, seemed the most hopeful of any produced hitherto, and was hailed with jubilation in many quarters. But, although it proved successful for the purpose for which, in the first place, it was designed, i.e. the classification of books, it has been found inadequate when applied to greater bibliographical detail, such as individual scientific and technical papers. In its original form it is therefore unsuitable for the preparation of a detailed index to the records of human work and thought.