Ernst Florens Friedrich Chladni

Chladni was trained as a lawyer — his father insisted — and hated it. The moment his father died, he turned to music and physics. He had no academic post, no laboratory, and no formal scientific education beyond an amateur's reading. He paid his way by touring Europe performing acoustic demonstrations, accompanied by his own invention, a glass-rod instrument he called the euphon.

In 1787 he published Entdeckungen über die Theorie des Klanges (Discoveries on the Theory of Sound), which laid out the experimental technique that made him famous: fix a thin metal plate at its centre, sprinkle fine sand on it, and draw a violin bow along one edge. The plate rings at one of its eigenfrequencies, and the sand, bouncing on antinodes and rolling to the motionless nodal lines, traces those nodes out as a sharp geometric pattern. Different frequencies give different patterns — stars, crosses, concentric rings, asymmetric flowers.

Chladni could demonstrate the patterns. He could not derive them. The mathematics — a fourth-order plate equation — was beyond anyone at the time. Napoleon, who saw a demonstration in Paris in 1809, was so taken with it that he offered a 3,000-franc prize through the Academy for a theoretical explanation. Sophie Germain won it (on her third try) in 1816; her theory was still not quite right, and the full treatment wasn't settled until the twentieth century.

Chladni also founded the scientific study of meteorites. His 1794 book arguing that 'stones from the sky' really did come from space, and weren't just folklore, was mocked for a decade before he was vindicated.