Dewey Decimal System

   One classification system used by libraries was devised by Melvil Dewey (1851-1931), the father of American library science. The number on the spine of a library book identifies its position on a shelf through a system known as the Dewey Decimal System, which is now employed by more than 85 percent of libraries in the United States.

   Dewey, born in Adams Center, New York, devised his classification apparatus while a student and acting librarian at Amherst College. In 1876, when Dewey was only in his twenties, he completed his method for classifying publications and published his system under the title Classification and Subject Index for Cataloguing and Arranging the Books and Pamphlets of a Library.

   Subsequently he helped found the American Library Association, the New York Library Association, and the Library Journal, for which he served as first editor. In 1883 Dewey became librarian of Columbia College (now Columbia University), where in 1887 he established the country's first professional school of library science.

   Dewey's system used numbers from 000 to 999, dividing the general fields of knowledge into nine main classes, all of which can be subdivided out to several decimal places.

   A system of classification was devised at the International Institute of Bibliography in Brussels. It extends the Dewey system, on which it is based, by using various symbols as well as Arabic numerals. The Library of Congress letter/number system provides more flexibility, however, for large collections.

   In 1889, Dewey introduced another innovation to facilitate the reading of books, the traveling library, now popularly called the "bookmobile." This system has been of particular importance to the rural community where access to public libraries is inconvenient.