Editing Bookcase (section)

== Library shelving ==
[[File:SteacieLibrary6.jpg|thumb|Parallel arrangement of bookshelves]]
[[File:Firestone Library Princeton mobile aisle shelving.jpg|thumb|Mobile aisle shelving]]
In the great public libraries of the twentieth century, multilevel [[Library stack|stacks]] often served as both structure and shelving,<ref name="ELH">{{cite book|editor-last=Wiegand|editor-first=Wayne|title=Encyclopedia of Library History|year=1994|publisher=Garland|pages=352–355}}</ref> of [[iron]], as in the [[British Museum]] where the shelves are covered with [[cowhide]]; or [[steel]], as in the [[Library of Congress]] in [[Washington, D.C.]]; or of [[slate]], as in the [[Fitzwilliam College, Cambridge|Fitzwilliam Library]] at [[Cambridge]].<ref name=EB1911/>

=== Systems of arrangement ===
There are three common ways of arranging stationary bookcases: flat against the wall; in stacks or ranges parallel to each other with merely enough space between to allow for the passage of a librarian; or in bays or alcoves, where cases jut out into the room at right angles to the wall-cases. The stack system is suitable only for public libraries where economy of space is essential; the bay system is not only handsome but utilizes the space to great advantage.{{citation needed|date=December 2011}} The library of the [[City of London]] at the [[Guildhall, London|Guildhall]] is a peculiarly effective example of the bay arrangement.<ref name=EB1911/>

For libraries where space is extremely tight there is yet another system, usually called [[Mobile shelving|mobile aisle shelving]]. In such systems rows of bookcases are mounted on wheels and packed tightly together with only one or more aisles between them. It is possible then to visit only two bookcase sides at a time, all the others being pressed close together. A gearing mechanism allows users to move the bookcases and open the aisle in the desired location. Because of the danger of tripping on the floor-mounted rails or being crushed between bookcases, these systems may have electronic sensors and/or recessed track, or may be reserved for closed stacks where access is restricted.