Frequency and vibrations.

I came across this article somewhere on the web, copied, closed the tab and now can’t even give credit to the site.  I think it was on futilitycloset.com.  Anyway, this is too cool:

In 1680 Robert Hooke sprinkled a plate with flour, drew a violin bow across its edge, and saw the flour spring into surprising geometric shapes. The plate was resonating, driving the flour into invisible nodal lines on its surface that were not vibrating.

German physicist Ernst Chladni pursued these experiments in the 18th century and published his results in Discoveries in the Theory of Sound in 1787. Today they’re known as Chladni figures.

“The universe is full of magical things,” wrote Eden Phillpotts, “patiently waiting for our wits to grow sharper.”