Johann Heinrich Lambert

Johann Heinrich Lambert was an Alsatian polymath from the Republic of Mulhouse, then an associate of the Swiss Confederacy, who lived from 1728 to 1777 and made fundamental contributions to mathematics, physics, philosophy, astronomy and map projections. Born into a Huguenot family, he left school at twelve for lack of money and educated himself while working as a clerk, tutor and secretary. In 1763 he joined the Prussian Academy of Sciences in Berlin, supported by Frederick II and working beside Leonhard Euler. He gave the first proof that pi is irrational, systematized hyperbolic functions in trigonometry, and was the first to treat the general properties of map projections, including the incompatibility of conformality and equal area; the Lambert conformal conic projection is named for him. In physics he invented the first practical hygrometer, wrote the Photometria in 1760 and introduced the term albedo, and the non-SI unit of luminance, the lambert, honours his work.