structural entity incorporating staircases and floors, and even capable of supporting a roof structure. He designed the shelves so that they could adjust to book sizes using a simple lug system without the need for any bolts or fixings. Although the bookstacks were decorated and very simply embellished, they are of machine-age industrial design. Open versus closed stacks In the design and administration of any library, a key decision is whether its stacks will be open or closed. In an open-stack library, patrons are free to enter the stacks to browse the collection and retrieve items that interest them. In a closed-stack library, only library staff are allowed in the stacks; patrons must use the catalog to identify books they want, and request that staff retrieve them. Until the late 19th century, most public libraries had closed-stack systems, but toward the end of that century open stacks increased in popularity. A notable proponent of the open-stack system was John Cotton Dana, who became head of the Denver Public Library in 1889. The first few Carnegie libraries used the closed-stack system, but later Carnegie Libraries were designed to operate with open stacks. Angus Snead Macdonald, president of the Snead Company from 1915 to 1952, advocated the transition from closed stacks to modular, open-plan libraries. See also Bookcase Harvard Depository An example of recent proposals regarding 21st century library stacks A controversial undertaking by the New Zealand National Library to dispose of half a million books from its stacks (a little over half of its reserves).Reactions and opposition. References Architectural elements Book terminology Library equipment