The books in the Library are at present arranged according to two systems:

1. The Library of Congress classification, slightly modified. It is expected that the entire library will ultimately be reclassified by this system. Letters are used for main classes, subdivisions are chiefly indicated by numbers. The subjects now included in this classification are:

2. The Rowell classification which covers all subjects not reclassified. In it instead of letters, the classes are indicated by numbers from 1 to 999 with some sub-classes given lower case letters following these. A brief table of important main classes follows.

All books in the stacks are arranged according to these classifications and shelf lists on cards are available in the Catalogue Room. These are useful because they show all books in a class whether or not they happen to be on the shelves at any one time.