Charles Dupin

Baron Pierre Charles François Dupin (6 October 1784 to 18 January 1873) was a French Catholic mathematician, engineer, economist and politician, born at Varzy in the Nièvre and known particularly for his mathematics, where the Dupin cyclide and the Dupin indicatrix are named after him, and for his work in statistical and thematic mapping. In 1826 he created the earliest known choropleth map. He studied geometry with Monge at the École Polytechnique and then became a naval engineer. His mathematical work was in descriptive and differential geometry, and he discovered the conjugate tangents to a point on a surface as well as the indicatrix. In 1808 he took part in the Greek science revival by teaching mathematics and mechanics lessons in Corfu.