Plumleigh Augusta Babbage’s Full Adder Brooch

In 2012, I started a steampunk costume that never seemed to take flight. The only finished piece is the skirt stay/brooch, created in collaboration with my friend Katherine Koba (who did all the beadwork, and continues to create the mathematically-inspired jewelry in her Etsy shop).

The backstory for the character I dreamt up to costume included Ada Lovelace as her godmother, inspiring her to tool about with Babbage’s analytical engines. While the character is fictitious, Lady Ada King, Countess of Lovelace was not—she’s considered the first computer programmer, having theorized how the Analytical Engine could do calculations decades before an electronic computer was built. So, in honor of Ada Lovelace Day (the middle Tuesday of October every year), here is a post about the brooch (finally!).

Full Adder skirt stay/brooch — “Plumleigh Augusta Babbage’s Adder Brooch,” Rachael Arnold and Katherine Koba, May 2013. Bead, wire, bicycle gears, spray paint, superglue.

With computers, everything boils down to zeros and ones—electric current on or off. Calculations are performed by circuits of varying complexities. One of the more basic is called a full adder, which we modeled this brooch after. As you might guess from the name, it adds numbers together.

full adder diagram — Diagram of a full adder

In the beadwork, the inputs are splayed across the top and the results (sum and carryover) are dangling from the bottom, with the gates and intermediate results between. The smaller, purplish beads are numbers—1 or 0—and the larger orange and gold represent the logic gates—gold for AND, orange for XOR. The white beads are filler for the paths between the gates.

The beadwork is mounted on a base made from bicycle gears (we can pretend they’re from an analytical engine) that were superglued together and spray-painted. I can’t speak for Koba, but I think sizing the wires correctly was the most difficult part of this—particularly since the gears and I were in Utica, and Koba and the beads were in South Korea!

Full Adder skirt stay — “Plumleigh Augusta Babbage’s Adder Brooch,” Rachael Arnold and Katherine Koba, May 2013. Bead, wire, bicycle gears, spray paint, superglue. Shown on draped fabric in intended position as a skirt decoration.

Plumleigh can’t do any actual calculations with this full adder, but it certainly is a fun accessory to wear while she fiddles with a real set of circuits solving any manner of problem.

Projects like this are just one of the myriad ways STEM sneaks into my crafting. How does it influence your hobbies?