The Man Who Chased His Own Equation

André-Marie Ampère founded the science of electrodynamics. In the fortnight after hearing about Ørsted's discovery in September 1820, he worked out that parallel currents attract or repel, formulated the force law that still bears his name, and coined the word solenoid. The unit of electric current is called the ampere because of him. His name is carved into the Eiffel Tower.

He was also, in every other respect, catastrophically elsewhere.

Ampère once picked up a pretty pebble on the Pont des Arts, admired it, remembered he was late, carefully slipped it into his pocket, and threw his pocket-watch into the Seine. On a wet winter night in 1836 he came home from the Sorbonne, tucked his dripping umbrella tenderly into his bed, and stood himself on the doormat. Annoyed by his cats scratching at his study door, he had a carpenter cut two holes in the wood, one large and one small, and was genuinely bewildered to learn the kitten could use the big one.

But his finest moment came on a Paris boulevard, mid-calculation, when he mistook the flat back panel of a parked fiacre for a blackboard. He chalked it dense with equations. The cab pulled away.

He ran after it down the street, trying to finish the proof.