invented technique to show modes of vibration on a surface. Chladni repeated the (1680) experiments of Robert Hooke to view nodal patterns produced when a violin bow was run along the edge of a plate covered with flour. Chladni's technique, first published in 1787 in his book, 'Entdeckungen über die Theorie des Klanges' (Discoveries in the Theory of Sound), consisted of drawing a bow over a piece of metal whose surface was lightly covered with sand. When resonance was reached the sand formed a pattern showing the nodal regions;
invented a musical instrument 'Chladni's Euphonium' consisting of glass rods with different pitches.
1799 - Chladni improved Robert Hooke's 'musical cylinder' to produce the 'Clavicylinder', in 1799