If you've ever tried to find a nonfiction book in the library, yo've noticed the numbers--Dewey Decimal numbers--printed on the little white spine labels on books. While we arrange fiction by the author's last name, we organize nonfiction according to the Dewey Decimal System. Each number corresponds to a certain subject. This allows for most of the books on a subject to be grouped together.

The Dewey Decimal System was invented by Melvil Dewey, who was born in Adams Center, NY, on December 10, 1851 (156 years ago today). Dewey began his career in librarianship while he was a student at Amherst College. Upon graduation, he remained an employee of the library and investigated other libraries. Dewey developed ideas about how the library should be arranged, and in 1876 published A Classification and Subject Index for Cataloguing and Arranging the Books and Pamphlets of a Library. (You've got to love those 19th century titles; they're often long and descriptive.) This system became know as the Dewey Decimal System. Although many colleges and universities use the Library of Congress Classification System, public and school libraries tend to favor Dewey. In fact, the Dewey Decimal System has become the most widely used library classification in the world.

How, exactly does the Dewey Decimal System work? Dewey is divided into ten main classes of knowledge. Then, each class is broken down into ten divisions, and each division into ten sections. This creates a three-digit number. A decimal point often follows the three digits. The numbers following the decimal point get even more specific. When you look at the numbers after the decimal point, be sure to read the numbers individually, rather than as a whole (973.12 comes before 973.2).

Knowing the main classes of the Dewey Decimal System will give you a general idea of where books are located in the Nashua Public Library or any other library that uses Dewey. They are as follows:
000 Computer science, information & general works
100 Philosophy and psychology
200 Religion
300 Social Sciences
400 Language
500 Science
600 Technology
700 Arts & Recreation
800 Literature
900 History and Geography
Click here to see the divisions, sections, and a more in-depth explanation of the classification system.

Sometimes, books you may assume to be in one area will be elsewhere. Many books cover more than one subject or are about a multidisciplinary topic. I've noticed that the 900s and 300s have quite a bit of crossover. History is located in the 900s, but political science, civil rights, slavery & emancipation, and international relations are in the 300s. Some books that I assume to be in one area are actually in the other. If you can't find what you need, check the online catalog for a specific call number or ask a reference librarian for assistance.

Sources:

"Melvil Dewey." Encyclopedia of World Biography, 2nd ed. 17 Vols. Gale Research, 1998. Reproduced in Biography Resource Center. Farmington Hills, Mich.: Thomson Gale, 2007 http://galenet.galegroup.com/servlet/BioRC

OCLC "Summaries, DDC Dewey Decimal Classification." Dublin, Oh.: OCLC, 2003. http://www.oclc.org/dewey/resources/summaries/deweysummaries.pdf