Library stack

More specifically, this term refers to a narrow-aisled, multilevel system of iron or steel shelving that evolved in the 19th century to meet increasing demands for storage space.

Although the structure was of cast iron, the shelves were made from strips of thin U section steel, designed to be as light as an equivalent pine shelf.

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.

In an open-stack library, patrons are free to enter the stacks to browse the collection and retrieve items that interest them.

A notable proponent of the open-stack system was John Cotton Dana, who became head of the Denver Public Library in 1889.