Jean Bernard Léon (ʒɑ̃ bɛrnar leɔ̃). 1819–68, French physicist. He determined the velocity of light and proved that light travels more slowly in water than in air (1850). He demonstrated by means of the pendulum named after him the rotation of the earth on its axis (1851) and invented the gyroscope (1852)

Michel. 1926–84, French philosopher and historian of ideas. His publications include Histoire de la folie (1961) and Les Mots et les choses (1966)