=307. Prints, Photographs and Maps.=--Unframed, unmounted “illustration” material, in which are included prints, illustrations, photographs, maps, and broadsides, requires separate and careful filing. In the first place it should be, so far as possible, mounted on “nature,” “sultan mecca,” or similar mounts of uniform size. This applies particularly to prints and photographs, and is the best means of ensuring their preservation and ease in handling and consulting them. They then need close classification by one of the existing systematic schemes to line on so far as may be with the classification of the books; and it is often necessary to expand a classification considerably to differentiate the almost innumerable sub-topics which may form the subjects of pictures. Such expansion is skilled work and should be done only by an expert classifier. An examination of the classification proposed for local photographic surveys in Gower, Jast and Topley’s _The Camera as Historian_, 1916 (Sampson, Low), will show how minute a classification photographs demand. Each mount should bear a label, in the top left corner preferably, giving the class-number, the subject, and other particulars (see the sections on Photographic Surveys, =433=, etc.). The filing may be in classification order in boxes which will lie flat on the shelves; and the most economical boxes are those made of the stoutest material compatible with lightness, such as cardboard covered with rexine, pegamoid cloth, etc.; heavy boxes of wood are awkward to handle and should be avoided. Better than boxes, because of the ease of consultation and insertion permitted, is a vertical file in drawers. In this the prints are inserted loosely like cards in a card-index, and no lifting and little handling are necessary to find any given print. For vertical filing the mounts should be the stoutest available, and a further protection is to use folders to hold groups of prints--one to a topic as a rule. The projecting edge of the folder may bear the topic number.