Most library users are familiar with one or two classification systems — the Library of Congress or Dewey Decimal. When researchers look in the Congregational Library's catalog, however, they are sometimes baffled by the call numbers assigned to the items in our collection. We are the first to admit that they're a little odd, but we do have our reasons.
The reason our call numbers don't look quite like anybody else's is because... we kind of made them up. Or mashed them up, to use more modern lingo. Our system isn't entirely original, but rather inspired by two other systems — Charles Cutter's expansive classification, developed for our neighbors at the Boston Athenaeum, and Ernest Richardson's decimal system, which originated in the Princeton University library — along with some tweaks and customizations from our past librarians to better suit the needs of our materials.
Because our collections are so specific, using LC or Dewey would result in us only using about half a dozen broad subject categories — history, religion, sociology, biography, reference, etc. By creating our own system, we can sort our materials in ways that are much more useful to our researchers. And even if they're unusual, our staff knows how to use the call number system to find whatever you need.
If you're interested in other idiosyncratic systems, the Mass. State Library recently featured a proposed location-based classification system that was never implemented. There are other topic-specific classifications like the Moody System used at Harvard for their international law collection, and format specific systems like the ANSCR (Alpha-Numeric System for Classification of Recordings) for audio materials.
Do you know of other quirky classifications? Do you have a favorite? Let us know.