145.
145. The following diagrams give the usual dimensions for ordinary standard and wall bookcases, and may be taken as the unit from which a library stack can be built up according to any plan of arrangement. [Fig. 31] represents a double-sized standard iron bookcase, 7 feet 6 inches × 3 feet 2 inches × 15 inches, which can be joined end to end to form cases of any length, or used in halves to form cases against walls.
Exactly the same dimensions can be used with wooden presses fitted with adjustable brackets or catches. In reference libraries the dimensions may be slightly varied, as the average book which must be stored is rather larger than in lending libraries. But the chief provision for folio and large quarto books should be in special cases arranged round the walls, and it is well to have presses intended for music and quartos fitted with uprights about eighteen inches apart, in order to distribute the weight of the books and facilitate their handling.
Fig. 31.—Double Bay Standard Metal Bookcase ([Section 145]).
146.
146. For standard reference cases the unit of size should be 7 feet 6 inches × 3 feet 2 inches × 18 inches. Special wall-cases should be the same height, but should have an arrangement for large books in the form of a ledged base projecting at least six inches from the front of the upper part of the case, about three feet above the floor ([Fig. 32]).
147. Adjustable Shelf Fittings.
147. Adjustable Shelf Fittings.—The old-fashioned varieties of shelf adjustments for wooden bookcases, such as pegs fitting into holes drilled in the uprights, one and a half or two inches apart, wooden or metal ratchets for carrying bars or rods for supporting the shelves, and similar devices, may be dismissed as unsuitable for modern library purposes. The best-known adjustment is that known as Tonks’, from the name of its patentee. It consists of metal strips, with perforations at inch intervals, let into grooves in the uprights, and designed to carry the shelves on four metal studs or catches, which engage in the slots or perforations. This method requires very careful fitting, as the grooves in the woodwork must be deep and smooth enough to admit the catches, and each metal strip must be accurately inserted so that the slots will come level not only with those adjoining, but with those on the opposite upright. The least carelessness in fitting will cause shelves to rock and buckle, because not supported by catches all at one level. The illustration on [page 145] ([Fig. 33]) will show exactly the form of this fitting. It consists of: shelf supported on standard; perforated metal slip and stud; and groove in wooden standard.
