THE BOOKSTACK TOWER 

       SYMBOL of the spectacular creation of a distinctly 
American library, keyed to the tempo of the times, the 
massive steel bookstack tower of the Sterling Memorial Library 
is a dominant and integral part of the architectural, engineering 
and administrative concepts of its builders.
       Two major principles were regarded as fundamental in 
the construction of the stack tower expansion flexibility, so 
that future growth can be taken care of without marring the 
symmetry or beauty of the original structure, and centralization 
of books to minimize time and effort in handling.
       The library is a working laboratory in the true sense of 
the word, and the bookstack tower is the heart of the structure, 
bringing readers and books quickly and easily together. 
With a present capacity of three and a half million 
volumes, the tower rises to approximately 150 feet. Built on 
skyscraper principles, it is subdivided into sixteen tiers or 
horizontal sections by means of thin marble deck floors, one 
and a quarter inches thick, and supported in a light steel 
horizontal framework of the bookstack. The waste of thick 
building floors is thus avoided, and the maximum amount 
of the cubical contents of the building utilized for the storage 
of books.
       Two thousand tons of steel and iron are incorporated in 
the construction of the stack, and one thousand tons of marble 
in the floor and stair treads. All steel connections, both 
horizontal and vertical, were welded together instead of being 
riveted, resulting in a solid, self-supporting, free standing, 
massive unit of steel. This was the largest welding job 
of its kind. The steel framework, supported on an eighteen 
inch thick concrete mat, carries the roof and braces the heavy 
stone walls.
       An interesting construction detail, originated for the 
Yale tower, is the adjustability of the shelf supports. These 
may be adjusted to take eight, ten, or twelve inch shelves.