I read about Chladni's figures (1787) when I was a kid.
A glass square is supported from the center on a stand,
and lycopodium powder - whatever that is - is sprinkled
over it, and bowed on the edge, while one point of the
edge is damped between the fingers.
Yesterday, I not only saw a Chladni's plate, but used it.
The plate was steel, the bow was a thick gut string on a
wire frame, and the powder was fine sand.
Moments like this don't come around too often.
There other interesting things to try: an acoustic tube
sprinkled with foam poly beads
and driven from a controlable frequency source, with a
removable end stop; a coupled pendulum pair; a Foucault's
Pendulum hung from the high joists.
I noticed the pendulum bob which was a fine looking brass orb
had a characteristic oscillation around its C of G from the
marker pillar knock-downs. In this respect a solid bell shape
would be better, I suppose.
These were some observations on a visit to the Omniplex center
at Oklahoma City, where the Air-Space, and Science Museums are
colocated.
brian whatcott <inet@intellisys.net> Altus OK
Eureka!