Colorized portrait of Johann Heinrich Lambert (August 26, 1728 - September 25, 1777), a Swiss mathematician, physicist, philosopher and astronomer. Lambert was the first to introduce hyperbolic functions into trigonometry and is credited with the first proof that pi is irrational. He also devised a formula for the relationship between the angles and the area of hyperbolic triangles. He invented the first practical hygrometer, and formulated the law of light absorption, the Beer-Lambert law, and introduced the term albedo. He was the first mathematician to address the general properties of map projections, and the first to discuss the properties of conformity and equal area preservation and to point out that they were mutually exclusive. In 1772 he published seven new map projections now known as: Lambert conformal conic, Transverse Mercator, Lambert azimuthal equal area, Lagrange projection, Lambert cylindrical equal area, Transverse cylindrical |