=186. Popular Books.=--The duplication of popular or temporarily popular books is a policy to be adopted with the greatest of care. In some libraries the plan of multiplying copies of every book which becomes fashionable is carried to such an extreme that some injury must be done to the general work of the library by unduly fostering one class of literature at the expense of all the other classes. The practice of adding six or more copies of a new novel has the effect of decreasing the funds available for the purpose of buying other works, and it certainly gives rise to misleading conceptions of the stock of books possessed by the libraries. A reported stock of 5000 novels may easily mean an actual stock of only 3000 different works in libraries which buy three, six or twelve copies of a single popular work. This makes a vast difference in the field of choice offered to borrowers, because, after all, popular novels of the ordinary much-advertised class soon have their little day, and the duplicates become dead stock. For this reason caution should be exercised in the supply of extra copies of temporarily popular books, and a good plan is to provide a special stock or accessions book in which they can be registered and, when necessary, written off without complicating the other records of the library. These remarks apply almost exclusively to the duplication of novels and magazines. There is less need to trouble about other classes. =187. Replacements and Out-of-print Books.=--Replacement of worn-out books is a recurrent, necessary and serious expense in most libraries, and one which gravely reduces possible expenditure upon new books. Before replacing an old, dirty or defective book it should be carefully considered if it is worth retaining in the library. Closely connected with the question of replacements is the matter of out-of-print books. Most librarians in libraries of several years’ standing have been confronted with the difficulty of obtaining copies of certain books which have been allowed to go out of print by their publishers. The number of such books is rapidly increasing, and among them are works which have taken a recognized place in English literature, as well as many others which have obtained a certain value by being enshrined in the catalogues of hundreds of public and other libraries. In course of time many of these books are worn out, and it becomes necessary to replace them with new copies. It is then the discovery is made that fresh copies cannot be obtained, and the librarian receives a long list of books from his bookseller marked with the ominous sign “O/P.” A temporary relief is sometimes obtained by advertising for second-hand copies. Even these are becoming more difficult to procure, and in the case of novelists like G. P. R. James, James Grant and Harrison Ainsworth, sometimes only three-volume editions are reported.