How do you organize your books so they can be found when you need them? For a "small" library almost anything goes: colour, size, alphabetically by author, alphabetically by title, etc. I have a modest number of scores and books about music acquired gradually over the last 20 years. For the longest time they were sorted alphabetically by author or composer or editor. Recently I looked through this collection and found forgotten treasures. Scores for recorders were filed next to scores for cello. Vocal music was next to string quartet music. My memory of what I owned was so degraded that I had no recollection of the pieces or where I'd bought them. Music that would be fun to play was lost in my filing system!

At this point it became clear that I needed to reorder my collection so it would be easier to find items of interest. Realistically my collection is so small that I could just come up with my own cataloging scheme and be done with it but, being a good programmer, I didn't want to reinvent the wheel. Why not stand on the shoulders of giants? This led me to the web.

A search quickly led me to a blog post by one of the librarians at the San Francisco Public Library about using the Dewey Decimal System to categorize scores. This seemed like a good way to go. If I could figure out the proper class number for each book or score, then sort them numerically, related items would be right beside each other. Also, I could use the SFPL's online catalog to my advantage. If they have the same books I have then I can just use their call number. No thinking required!

If only life was that simple.

Since I had to start somewhere I chose "The Oxford Companion to Musical Instruments" by Anthony Baines (ISBN 0-19-311334-1). Many books include the Dewey class number on their copyright page and this is one of them. According to the OUP, this book should be filed under 784.1903. As a check, just to be sure that my technique was viable, I looked it up on the SFPL web site. To my surprise they gave the call number as 781.91. Why the discrepancy? Which number is right?

After hitting this roadblock my enthusiasm (and progress) slowed somewhat. Finally, in desperation, I wrote to the librarians at the SFPL via their Ask a Librarian web page. I said,

I wish to use the Dewey Decimal System to arrange my personal library of books about music and musical scores. Your page of Musical Scores Call Numbers (http://sfpl.org/librarylocations/main/art/scoresearch.htm) is a great resource. However, I have noticed discrepancies between the numbers you assign books and the numbers others assign them. For example "The Oxford Companion to Musical Instruments" by Anthony Baines is given the DD# 784.91 by the publisher. In your library it is 781.19. Which number is correct and why? Any information you can provide would be much appreciated.

(Note that I jumbled up the numbers. Sheesh.)

One of the librarians there very quickly (and kindly) responded,

A radical revision was made to the music numbers of the Dewey classification in the 20th ed. (mid-1980's). It was decided at that time that SFPL would not start applying the new numbers, but would continue to use the (19th ed.) old schedule - in fact, a "customized" version of the old schedule.

Aha!

I imagine this was a difficult decision to make. Suppose your library has 20,000 music books and scores categorized using the the old schedule. How much would it cost to re-catalog all your books? Say it takes 15 minutes to figure out a new number. (This is obviously a wild guess. In future blog posts I will discuss how I compute a Dewey class number for a book and you will see that 15 minutes is probably an underestimate when you're striving for accuracy.) That means a librarian could classify four books in an hour. So it would take 5000 hours to reclassify all your books. In one year, if you take two weeks holiday, you work 40x50 = 2000 hours. That means it could take a single librarian two and a half years to reclassify all those books. You can start to see why they decided to stick with the old schedule. (According to the blog post referenced earlier, the SFPL may have as many as 45,000 actual items to catalog.)

Of course, on the flip side, now whenever a new music book or score is acquired you cannot use the publisher's determination of the Dewey class number. For each new book you need to return to first principles to figure out where it belongs. Suppose over time your library doubles in size from 20,000 to 40,000 books. You have now spent as much money re-categorizing new books using the old schedule as it would have cost to switch all your old books over in the first place.

When money is tight this is a tough call to make. How do you balance a huge upfront cost against an long-term, ongoing one? I suspect the latter is easier to hide in the budget.

Although I would like to use the SFPL call numbers as a labour-saving tool, it is pretty clear to me that I should use the new schedule for my music library. As luck would have it, my local library has the 20th edition of the "Dewey Decimal Classification and Relative Index" reference manuals. Now all I have to do is learn how class numbers are calculated.