Most classified catalogues are issued in this manner. But, in spite of the admitted advantages of the complete printed catalogue in book-form, the tendency is to depend upon complete manuscript catalogues at the library, and to advise readers of additions by means of a periodical library bulletin, by duplicated lists, by lists published in the local newspapers, etc. The open access system has destroyed the most immediate necessity for the printed catalogue--the choosing of books from a stock which readers were unable to examine--and few libraries which publish such a catalogue can hope to recoup even a substantial part of the cost from sales. One or two libraries have a _selected_ printed catalogue, which contains the 10,000-20,000 invariable books in the library--the classics in all branches of literature which readers have a right to expect to find on the shelves--and depend upon MS. catalogues for the stock as a whole. =260. Card Distribution, etc.=--In using the term “manuscript catalogue” we speak somewhat loosely, in that the term usually covers any catalogue not in printed _book_ form; hence it covers slip, card, sheaf, placard and various other forms in which individual entries may indeed be printed. The most used of these is the card catalogue, in which each entry of books is made on a separate card, and the cards are arranged on their fore-edges in drawers or trays (but drawers preferably) in the order that would be used in a book-catalogue. The merit of this system is its infinite flexibility; for, as every book has its separate card, cards for additions can be inserted without dislocating the order, and the catalogue can be kept up-to-date always. Several of the great bibliographical and cataloguing institutions have adopted this form, the most important being the Library of Congress at Washington. This admirable library not only prints its own cards, but offers copies for sale to other libraries at a low cost. In 1914 these cards were available for 650,000 titles, and to these additions of from 50,000 to 55,000 are made annually. As the cards are of standard size (5 inches × 3 inches = 12·5 × 7·5 cm.) they can be used in any properly constructed catalogue. Naturally there is an emphasis on American books, but thousands of the cards apply to English books as well. Thus, for an expenditure of about two cents per card, any library may have the cards for its catalogues, and this is at a far smaller cost in labour and money than any individual printed entry can be obtained by any library. The backbone of the system is the “unit” card; that is to say, one card is printed for a book and on it are indicated all cross-references, etc., and extra copies of the card can, if it is thought necessary, be purchased and placed under the headings indicated. The Library of Congress issues advance proof sheets at a charge of $30 a year, which may be cut up and mounted on cards as a staff catalogue, or as