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LESSON 5 CONTENTS: |
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Our discussion up to this point has focused on the important work catalogers do in terms of assigning authorized subject headings to a book. Through their efforts, the subject content of each item in a library is carefully described. But that is only half the story. Libraries must also organize their entire collection in some systematic way so that books can be found quickly and easily. How is this enormous challenge faced? As mentioned earlier, libraries organize their collections according to subject matter. This arrangement is intended to be convenient for library users since books on the same subject are placed together on the shelf. But in order for subject-based organization to succeed, it must be based on a definite and established plan that can be referred to again and again. Therefore, libraries have created classification systems. A classification system is an established plan that divides all knowledge into precise categories and subcategories. Each category is called a "class" and each subcategory is called a "division" or "subdivision." This division of knowledge always proceeds from general classes to more and more specific subdivisions. Each class and subdivision is assigned a specific symbol, thus insuring that books on that subject will always be classified (i.e. grouped) under that symbol. The symbols used are letters, numbers, or a combination of letters and numbers, depending on the classification system being used.
THE DEWEY DECIMAL CLASSIFICATION SYSTEM In 1872, Melvil Dewey devised the first major classification system
used by libraries. Known as the Dewey Decimal System,
it divides all knowledge into ten main classes numbered 000 to 900:
These ten primary classes are then split into divisions, which can be subdivided even further through the use of decimal numbers. For example, here are the ten divisions and a few subdivisions for the 900 main class (Geography / History): 900 Geography/History
980 General history of South America
Notice that the Dewey system uses numbers – not letters --
to signify subject categories, and that additional decimal numbers
represent greater subject specificity. Although most public libraries
use the Dewey system, most college and university libraries (including
Skyline) use a different classification system: the Library
of Congress Classification System.
THE LIBRARY OF CONGRESS CLASSIFICATION SYSTEM Devised in 1897, the Library of Congress Classification System (or LC System) is a highly detailed system that uses combinations of letters and numbers to represent subject areas. It divides all knowledge into 21 main classes indicated by a single letter of the alphabet:
These main classes are broken into principal subdivisions by an added letter. For example, here are the principle subdivisions of the Fine Arts main class (N):
Principal subdivisions are in turn subdivided by adding numbers to the letters. This dramatically expands subject specificity. For example, the NB subdivision is subdivided with numbers as follows:
It’s not necessary to memorize all the details of the two library classification systems. However, it it’s very useful to know which is being used in your library (Dewey or LC) and its basic structure. Become familiar with the classification letters and numbers -- usually referred to as the class number -- for the subject or field in which you are doing research. For example, in the LC system, the class number for economic history is HC10 through HC1085. Knowing this, you can go to that section of the collection, browse the shelves in that call number range and find materials on that subject grouped together. You should also be aware of the following general principles regarding classification systems: 1) A single class number does not necessarily embrace all the books on a given subject. Although it’s useful to know the class number for a subject that interests you, keep in mind that a single class number does not necessarily embrace all the books on that subject. Theoretically, a library classification system would place books on any one subject in only one place on the shelves. However, this becomes impossible for books that deal with more than one subject. For example, a book such as Women, Philosophy, and Sport: A Collection of Critical Essays (Scarecrow Press 1983) could be classified under women's studies (HQ), philosophy (B), or sports (GV), which are far apart from each other on the shelves (Mann 50). However, only one class number can be assigned to this book and a cataloger will have to decide by examining the book and choosing the class number that corresponds to the subject covered most prominently by that book. Subjects covered in the book but not reflected in the call number will be described by additional subject headings assigned by the cataloger.
For example, someone could write a book on the Great Depression and discuss it as an historical event, which would place it in the history class (E). Another author's book on the Great Depression could discuss it from an economic perspective, which would place it in the economics class (HB-HD). A third book could discuss the Great Depression from the point of view of sociology and it would belong in the sociology class (HM). These two principles illustrate how complex subject classification can be. Therefore, you must rely on the online catalog for comprehensive subject searching. The online catalog will be discussed in part 2 of this lesson.
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