=190. Special Collections.=--The most necessary work of the library, after it has formed its general collection, is to collect local literature; this we deal with in a separate chapter (XXVIII.). Most public libraries possess some kind of special collection in addition to the purely local collection. Examples of these may be specified in the Shakespeare and Cervantes collections at Birmingham; the Burns and Scottish poetry collections at Glasgow; music, shorthand, Chinese books, etc., at Manchester; fishes at Cheltenham; Welsh literature at Cardiff, etc. The literature of special local industries should always be collected. Representative works in foreign languages, particularly French, German and Italian, should also be collected, in addition to the Greek and Latin classics; and the large and more cosmopolitan cities may endeavour to represent every foreign literary output so far as their circumstances warrant and their finances permit them to do so. =191. Sets of Periodicals.=--Some discrimination must be made in regard to the collecting of periodicals. Larger libraries settle the question by securing and preserving sets of all magazines of value which they can accommodate; but obviously the expense of the practice, the ephemeral character of much of this type of literature, and the large amount of shelf space it requires, makes that practice impossible for any but the largest libraries. Ephemeral, but otherwise wholesome, magazines may be used unbound for issue in lending libraries to good purpose; or may be bound and so used--but not replaced when they are worn out. Only periodicals which have a _reference_ value should be retained in sets, and then only where the geographical situation of the library warrants that course. A smaller town near a great town library may reasonably refer its readers to that library for sets of expensive periodicals. We are led to this view by the facilities now at the disposal of librarians through the Library Association. That body now publishes the _Subject Index to Periodicals_, hitherto called _The Athenæum Subject Index_--an invaluable and indeed indispensable tool for all librarians--and by an arrangement with the Central Lending Library for Students, Tavistock Square, London, W.C., any article recorded in the _Subject Index_ may be borrowed for a payment of about fourpence. The _Index_, moreover, gives a list of the principal periodicals, and is a rough guide to assessing their permanent worth as well as an admirable key to their contents.