Louis Bertrand Castel (15 November 1688 - 9 January 1757) was a French mathematician born in Montpellier, and entered the order of the Jesuits in 1703. Having studied literature, he afterwards devoted himself entirely to mathematics and natural philosophy. He wrote several scientific works, that which attracted most attention at the time being his Optique des couleurs (1740), or treatise on the melody of colours. Read more