In addition, a series of bold class labels at the top of each class, and plenty of topic labels on the shelves, together with the progressive class numbers boldly printed, and fixed to the end of each shelf, will be found a great help to understanding the classification and finding the books. Shelf topic and number labels can be printed by the staff with an ordinary rubber-printing or sign-writing apparatus, and they can be fixed to the shelves by means of the label-holders mentioned in Section 249. For class numbers on the shelf-ends xylonite label-holders will be found economical and convenient, as they can be cut into inch widths. The above figure (Fig. 76) of a shelf-front with labels will give some idea of the application of these marks. The class number of the first or last topic only need be given. A method of guiding by tiers instead of by shelves is described in _The Library World_ (Nov. 1904) and is one of many experiments which have been made with shelf guiding. The illustrations (Figs. 77, 78) will show much better than words the appearance and possibilities of this system. Another form is illustrated below (Fig. 79) and shows a class label for indicating the chief contents of a main class. The illustration of an open access lending library given opposite (Fig. 80) shows the system of press guides used at the North Islington Library, which in practice has been found very effective. +---------------------------------------------------+ | | | A | | | | GENERALIA. | | | | 000 GENERAL 500 GEOMETRY | | 100 EDUCATION 600 GRAPHIC AND PLASTIC ARTS | | 300 LOGIC 900 GENERAL SCIENCE | | 400 MATHEMATICS | | | | For Special Subjects _see_ Index to Subject | | Classification. | | | +---------------------------------------------------+ FIG. 79.--Class Guide (Section 244). =245. Shelf Register.=--The shelf register is a record of the books as they stand on the shelves, and is the main guide used in stock-taking and otherwise checking the books. Cards are sometimes used for this purpose, each work being entered on a separate card, the whole being arranged in trays in the order of the classification. [Illustration: FIG. 80.--Bookcase with Classification Guides and Shelf Labels (Section 244).]