March 1, 2020

Library Life: Dewey Made Easy

Last time, I discussed call numbers on youth literature. Today, I tackle nonfiction, which is organized according to Dewey Decimal Classification (DDC, for short). Unfortunately, some people hear the phrase “Dewey Decimal System” and give up on the spot, sure that this century-and-a-half old system is far too cumbersome for the laymen to work with. Not so! And, as someone who is positively in love with nonfiction, I’m here to tell you how to navigate it.

See, Melvil Dewey was obsessed with simplification and classification, even from his youth. He decided that there ought to be a way to categorize all human knowledge, and so created his decimal system. There are ten main classes, broken into a thousand subclasses—these are the numbers to the left of the decimal point in any nonfiction call number you come across. The numbers to right of the decimal, in the tenths, hundredths, thousandths, and so on places, are even smaller, more specific categories. Essentially, Dewey found a way to place any subject into a large category, and then specify where it should live by creating more and more little sub-sub-sub categories. Brilliant!

But you don’t have to know any of that.

I brought it up to give a little history, and to pay Dewey his due. What you need to know is, DDC works like a number line.

Let’s say you look up a book in a library catalog, and it says 170.44 PET for the call number. First, you would go to the 100s section, close to the beginning of nonfiction, and travel past the 140s, 150s, and 160s until you get to 170. Easy! Then you travel past the 170s with no decimal (because they are secretly 170.0; who said you’ll never use math in real life!), past 170.1, 170.2, and 170.3 until you get to 170.4. And then, realizing that 170.44 is larger than 170.4 (that is, 170.44 > 170.40), you keep on going, stopping just before you get to 170.45. Hazzah! 170.44! Think of it like a number line, and you can find anything.

Now, the library which I work in is pretty small, so in general, once you find the number, you’ve pretty much found the book you’re looking for. Some sections, though, are much larger, so we’ll need to use those three letters after the decimal, which stand for the authors last name. Take most true crime, which is 364. Let’s say you want to read Devil in the White City, by Erik Larson, and the catalog says its call number is 364.1 LAR. You find DDC number 364.1. In fact, you find a whole shelf of it! All you have to do is go alphabetically, looking at the letters of all these various crime authors until you get to LAR for “Larson”. Easy! Bigger libraries use a combo of letters and numberscalled "cutter numbers"to represent the author, but they still go alphabetically and numerically, and follow the alphabet/number-line pattern.

Of a final note, some nerds like me like to not just find individual books, but to actually browse nonfiction. Thus, it can be helpful to learn what the numbers mean, at least in your particular area of interest, whether that’s history (900s), medicine (610s), or the paranormal (001.9, 133, and 398). Wikipedia has a nice break down of all one thousand. So give Dewey a try; you just might find your next favorite book!

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