Chladni figures

Chladni figures

One of Chladni's best-known achievements was inventing a technique to show the various modes of vibration on a rigid surface, known as Chladni figures or Chladni patterns due to the various shapes or patterns created by various modes. When resonating, a plate or membrane is divided into regions that vibrate in opposite directions, bounded by lines where no vibration occurs (nodal lines). Chladni repeated the pioneering experiments of Robert Hooke who, on 8 July, 1680, had observed the nodal patterns associated with the vibrations of glass plates. Hooke ran a violin bow along the edge of a plate covered with flour and saw the nodal patterns emerge. Hooke had already observed this 9 years earlier in 1671, and in turn was inspired by a suggestion he read in Bacon's Sylva Sylvarum, where Bacon describes rubbing the rim of a glass filled with water and observing the water "frisk and sprinkle". Hooke presented this in 1680 to the Royal Society, and there was no follow-up.