Thursday, September 28, 2006

Apple #198: Dewey Decimal System

Yes, Dan, there really still is a Dewey Decimal System. And thanks for asking!

For those of you who may not know, the Dewey Decimal Classification system is a method of organizing materials, usually in a library, according to their subject. Think about it this way: you're standing in a library, book in hand. Where do you put the book? Say it's a book about robins, written by one of your favorite authors who also writes a lot of fiction, say Alexander Dumas. Do you put the book with other non-fiction books about robins, or do you put it next to books written by Alexander Dumas? This system helps you make that decision.

Next, you use the system to assign a code to the book. That code gets entered in a list of all the books in the library, and you can use the list to help you find that book again later, as well as any other book in the list. The list is called a catalog and the code given to each book is called the catalog number. The number gets printed on the spine of the book, and then you shelve the book about robins sequentially next to books with a similar number.

There are actually two major classification systems like this used in libraries in the United States and in libraries internationally. The other system, besides Dewey, is referred to as the Library of Congress Subject Headings (for those who know it on an informal basis, LC).

LC is much more comprehensive and detailed than Dewey and is most often used in larger libraries at universities, or at libraries with very specialized collections. The Dewey Decimial Classifaction system (DDC) is used most often in small to medium-sized libraries. Your local public library probably uses Dewey.

In fact, the Dewey Decimal system is the one most widely used in the world. It was originally developed by a guy named Melvil Dewey in 1876.

Melvil Dewey, looking kind of young
(Photo from the Harris County Public Library)

The Dewey Decimal System is now owned -- yes, it is intellectual property that has been bought and paid for -- by a company called OCLC, the Online Computer Library Center. OCLC is actually a consortium, but a very powerful one in the library world. Essentially, they provide the software that the vast majority of libraries use to catalog their collections. You can use software that will catalog according to Dewey or LC, as you choose for your library.

One of OCLC's buildings at headquarters in Dublin, Ohio
(Photo from OCLC)

  • If your library uses Dewey, the code on the spines of the books will start with numbers. If your library uses LC, the codes will begin with letters, followed by numbers.
  • Melvil Dewey devised his classification system in 1876, when he was 45 years old. He also helped found the American Library Association in the same year, he edited one of the oldest magazines about books and libraries, the Library Journal, and he is generally recognized as the founder of library science in the United States.
  • Mr. Dewey also promoted the metric system. Makes sense, since his Decimal System works pretty much in base ten, as does the metric system.
  • The Dewey Decimal System divides all fields of knowledge into ten major subject classes, indicated with the numbers 000 through 999. Each 100 mark denotes a new subject.
    • 000 Generalities
    • 100 Philosophy & Psychology
    • 200 Religion
    • 300 Social Sciences
    • 400 Language
    • 500 Natural Sciences & Math
    • 600 Technology & Applied Sciences
    • 700 Art, Sports, & Recreation
    • 800 Literature & Rhetoric
    • 900 Geography, History, Biography
  • Categorizations within a given subject are indicated by changing the numbers within that 100-level. Here's how we would make some cataloging decisions for our book about robins:
    • At the 100-level, we'd use the 500s, for Natural Sciences
    • At the 10-level, we'd use 590s, which is for books about Animals
    • At the 1-level, we'd use 598, which is for books about Birds
    • Next comes the decimal, and we'd proceed from there, with greater specificity at each step until we have a code that describes this and only this book.
  • One of the biggest problems with the Dewey system today is that there really isn't room within it to handle books about computers, hardware, software, video games, and that sort of thing. None of that technology was even imagined in the 1870s, and there just isn't a whole lot of room in the 620s (Engineering) for all the information about computer technologies.
  • If you go to your library's section on computers and look at the catalog numbers on the spines of the books in that section, you'll see that the numbers are probably really really long. That's because the only way the cataloger could get specific enough about the book was to add more sub-categories within the 620s.
  • For similar reasons, the Dewey System can sometimes result in awkward cataloging of non-book media, like music recordings or movies -- how do you indicate that something's on VHS as opposed to a DVD? Most libraries just put VHS before the catalog number or the like, but that means essentially that the Dewey System has to be modified to accommodate these other formats. And what do you do for software that's written for a PC as opposed to software written for a Mac?

Clearly, librarians are not the only people who have trouble figuring out what to do with piles of floppy disks
(Photo from ACT/Apricot)

  • Questions arise not just because of modern formats or technology. Just this year, the Lords of Cataloging at OCLC couldn't figure out how to categorize a book written by Jim Belushi called Real Men Don't Apologize.

    • "With all due respect to the author," said Leslie Buncombe, chair of OCLC's Editorial Policy Committee, "we remain unsure how to categorize this particular work. What is it? Autobiography? Self-Help? We can't even tell if it's fiction or non-fiction. Maybe it's Fantasy Biography?"
    • I have encountered many books that walk that weird line of "I'm a celebrity and I'm going to tell you about my life and maybe give you some tips but also just talk about how great I am." It is hard to know what to do with those things sometimes.
    • Buncombe isn't even sure this particular item is "an actual book."
  • I should note that catalogers have to make decisions like this all the time, regardless of what cataloging system they're using. In other words, just deciding to use LC instead of Dewey doesn't mean you won't encounter similar types of questions.
  • Any system of classification will have its shortcomings because really nothing can encompass the scope of all human endeavors across all times. After all, that's what these classification systems are trying to do. When you think of it that way, it's really remarkable that they hold up as well as they do.

Only one entry left to tell me your top five favorite Apples! Some of you, I know, already have your five favorites in mind. Now's the time to post 'em, please.

Rutgers Moving Image Collection, Glossary of Cataloging & General Terms
OCLC, Dewey Decimal Classification System
Middle Tennessee State University, Let's Do Dewey
Duke Libraries, How the Dewey Decimal System Works and Outline of the Dewey Decimal System
"Dewey Decimal System Helpless to Categorize New Jim Belushi Book," The Onion, August 14, 2006

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