Thanks for all the great guesses at the identity of the December Crocodile! In fact, the mystery object is a tool for removing the rod from a particular type of card catalog drawer (see Folgerpedia‘s Card catalogs article for information about our card catalogs and how to use them).
Ironically, Richard M. Waugaman’s tongue-in-cheek proposal that it’s a worn-out corkscrew comes closest to the actual function: this type of card catalog rod is removed by jamming the tool onto the end of the rod and pulling, just like you’d pull a cork from a bottle. It’s sometimes called a “key” but it is purely a friction fit, not something that triggers a release mechanism. Personally, I call them card-catalog-rod-puller-outers.
The discoloration that Daniel R Harris noted about a third of the way from the end matches the depth of the knob on the rod, and was caused by decades of scratches from twisting the rod out of the drawer with the tool attached.
Card catalog rods are a convenience as well as a safety feature. Without them, an entire drawer of cards could be dumped by accident (inconvenient) causing the person who has to refile them to have a heart attack (dangerous). Rods also serve a quality-control function, as described at the end of the post.
There are five main types of card catalog drawer, and all five can be found at the Folger.
Friction-fit rod: If you don’t have a card-catalog-rod-puller-outer, try pulling with just your fingers (sometimes the rods are quite loose). If that doesn’t work, try pushing on the rod from the other end (a small crowbar can be useful).
Threaded rod: Grasp the knob, turn it counter-clockwise to unscrew, and hope that the person who last screwed it in had a gentle touch (if not, a vise grip wrench can be useful).
Lift-and-pull rod: In one smooth motion, lift up on the knob and pull out the rod. This can be done one-handed if you use your thumb on the drawer handle for leverage.
Hidden-release rod: Pull the drawer out a little bit, peer inside, and look for a tab or button of some sort. Figure out if it needs to be pushed, pulled, slid to the side, or whatever. Push it, pull it, or slide it to the side with one hand while pulling on the rod’s knob with the other hand. Extra points for doing this while holding your notepad under your chin and clenching a pencil between your teeth.
No rod at all: Pull the drawer out a little bit and hope the card you need is near the front. If it’s near the back, and you have to pull the drawer almost all the way out, do not lift up on the drawer unless you are prepared to fully support its weight and carry it to a level surface.
Rods also serve a quality-control function: when filing cards, you always file “above the rod.” That is, you leave the rod in place, and file the cards where you think they ought to go. Once you’ve filed all the cards in a batch, you or someone else can easily double-check the filing by flipping through the cards that are sticking up. After verification, it’s time to “drop the cards” by pulling the rod out just far enough to allow the new cards to fall into place as you wiggle the rod back in.1
Note that even though we no longer update or add to the card catalogs at the Folger, we do still have a card sorter and a marked-up copy of the ALA Filing Rules for Catalog Cards that shows which options the Folger opted for.
You just never know.