Once again we return to "The Heterodyne Boys and the Dragon from Mars" to find yet another hidden reference, in-joke, or layer of foreshadowing.
...which is to say, I think I've solved the clockwork ducks.
Meet the Canard Digérateur, or Digesting Duck!
Like the more-famous Mechanical Turk, it's a fraud.
Qualifying indeed as a clockwork duck, it was supposed to eat, process, and excrete food, generally grain, of course for a paying audience. (It didn't. Grain could go in, but the excreta was pre-loaded in a separate, unconnected compartment.) The device was a marvel for nearly 80 years before someone caught on.
Wikipedia has a list of literary appearances, including one in which "Vaucanson's duck attains consciousness and pursues an exiled Parisian chef across the United States." (I'M INTRIGUED?!) One of them is a novel called Spark! Yes, really.
Wikipedia does not mention its cameo in Girl Genius.
I presume Theo put it into his story because it's hilarious, so Rule of Funny covers why fictional Klaus would have one, much less multiple. It is indeed the sort of thing that the kids Theo was entertaining would know about and laugh at.
Many thanks to Professoressa Kaja for mentioning "the duck" during this Wednesday's Twitch office hours, and no thanks to my brain for taking three whole days to run a simple "ducks + early Girl Genius" keyword search, making me sit up in the middle of the night and go "HANG ON A SECOND, that's a REFERENCE?!"
And now we know.
