Page:Library Administration, 1898.djvu/183

 become the practice to recommend three size-classifications, only corresponding roughly, folio, quarto, and octavo, running horizontally one above the other. This idea is found impossible of execution in the storage of modern books, folios and quartos being rarely used except for costly illustrated books, which are often withdrawn from the arrangement in order to subject them to special precautions. The term "press-mark" of course falls out of use where the relative-location system prevails, since the distinguishing marks are attached to the books themselves, not to their receptacles. The simplest form of marking consists in numbering the books successively as they stand on the shelves. This evidently is only possible where the accessions can be placed at the end, for if they had to be incorporated in various places, there would be no number available. This elementary proceeding is used sometimes in free libraries for marking the class Fiction, which needs no classification. The typical instance of elaborate marking is the Dewey-Cutter system, which largely prevails in the United States. The books stand on the shelves in the order indicated by the "decimals" belonging to them in the classification. As, however, even the most elaborate of these decimals only denote classes of books, a further indication, the "book-number," is required to guide the searcher to the individual book. This may be selected in various ways. (1) The accession-number, or number attached to the book in the