But although we hesitate, perhaps, to tear to pieces good books, even for such a good purpose as this, there is much material that can be so treated with a clear conscience. Many duplicates of art works can be thus used, and there is hardly an illustrated book which when the librarian is ready to throw it away does not contain plates or maps which can be saved and used. In St. Louis when we condemn books they are never destroyed and consigned to the old-paper dealer before passing through the hands and before the eyes of all those who might use still usable fragments of this kind. Taking the item of maps alone, some of the best special maps are attached to volumes of travel or history, as folders or in pockets. So long as the book is usable, the map, of course, must go with it, but if the map has been reinforced with linen when the book is purchased, as it ought to be, it will probably be in usable condition when the book is worn out, and may at once be transferred to the map collection. The same is true of other plate than pictures--fac-similes of handwriting, for instance. A very fair autograph collection may be made of such detached plates--not originals of course, but originals are valuable merely as curiosities, in the way that we have already noted. Fac-similes are as good for any other purpose. Of course all such torn up or detached material is very convenient also for reference use--easily filed and quickly consulted. It may be kept in vertical file cases, in loose-leaf binders or in ordinary portfolios. One of the interesting things about it is the facility of assembling it in different ways. In our own library we sometimes tear apart the leaves of an art book simply to group the plates in an order that will make them more valuable for reference purposes. This leads us to another nearly related, though I should call it a still further, step toward the museum region, which is taken when we deliberately create specimens by clipping and mounting. Most libraries are now doing this freely, both for reference work and for circulation. In many cases there are no separate labels here except a brief descriptive title, the material being classified according to its subject or its intended use. The similarity to the school museum or circulating museum--a very recent development of museum work--is striking. In this field the library has been ahead of the regular museums. The material clipped and mounted is usually book material--largely plates from books, magazines or papers. There is much other material that can be so mounted and used--the kind of thing that is familiar in memorabilia scrapbooks--theatre and concert programs, announcements, invitations, tickets of admission, badges, menus, photographs, advertising material, etc. It is usually a mistake to make permanent scrap-books of such material. When they need to be assembled in book form the separate mounts can be brought together in a loose-leaf binder.