=311. Lantern Slides and Negatives.=--Modern libraries collect and preserve, occasionally even make for their own use, lantern slides and negatives. The method recommended for storing these is precisely similar to that for prints; that is to say, in drawers in cabinets of suitable dimensions. Such cabinets are made by several firms specializing in photographic apparatus; and drawers can be obtained of a size to accommodate either slides or negatives. Without being dogmatical upon the point, it may safely be said that the best arrangement of slides is a classified one in drawers, the classification number being written on a label on the mount of the slide and on the top edge of the binding. If the slide is made from a negative in the possession of the library the number of the negative should also appear on the mount. =312.= Negatives require more careful treatment, as the film is subject to damage if unprotected. They are also generally larger than lantern slides; and separate cabinets, or separate drawers, are desirable to hold them. A useful method is to insert each in a small manilla folder bearing the number on its edge, which number should also be written in ink (white is best) on the corner of the negative. Negatives may be arranged by accession numbers, as they are rarely wanted more than one at a time; and the slide catalogue will refer from slide to negative, as well as be a direct reference to the latter. =313.= The index or catalogue of slides may be on cards arranged as a rule by titles or subjects, as the photographer or slide-maker’s name is rarely wanted. The following example of a card shows the title, source, location, and classification number of a slide and the number of its negative: +------------------------------------------------------+ | 656 LOCOMOTIVES. | | Ble | | Blenkinsop’s Engine, with Rack-Rail, 1811. | | | | | | | | | | | | Print-- Lantern Slide-- | | Process Coloured. | | Size 3 in. × 3 in. | | Negative 18. Lecture--Railways. | | 66675 P. | | | +------------------------------------------------------+ FIG. 119.--Lantern-slide Index Card (Section 313). Slides which form lecture sets and are invariably used together, may be filed as sets, in spite of the fact that the others may be classified. After all, the rule of classification itself is that things used together must be placed together.