Somebody else said that such a beast was featured in an animated series
called Nadia.
It just so happened that I finally was able to see this series as a whole.
The original title is `Fushigi no umi no nadia' aka `Nadia et le secret
de l'eau bleue' here in France, probably know as `Nadia and the secret of
the blue water' in the USA (not to be confused with `la Blue Girl', a quite
different series), the first series produced by Gainax, a team of animator
quite famous in japanese animation circles.
The first episode takes place at Paris Universal Exposition in 1899,
and it does indeed feature a monocycle ! used by the hero, Jean to rescue
the heroin, Nadia, doing some impossible acrobatics on the side :-)
This particular machine is never seen again through the whole series,
though there are lots of other surprising inventions and original vehicles.
I must say that this series is very nice, and has somewhat of a circus
flavor---after all the heroin starts as an acrobat/animal handler performing
in a circus.
If you can, check it out, at least the first episode.
-- [nosave]<http://www.eleves.ens.fr:8080/home/espie/index.html> microsoft network is EXPLICITLY forbidden to redistribute this message. `Seiza no matataki kazoe, uranau koi no yuku e.' Marc Espie (Marc.Espie@ens.fr)