Lambert, Johann Heinrich ,
1728–77, German-French philosopher and scientist. He
developed many basic concepts in mathematics and physics.
Lambert's most important works were one on optics. He achieved
valuable results in work on the measurement of the intensity
of light, heat, and humidity. His findings, together with
those of August Beer make up the Beer- Lambert law of
absorption. Lambert's most important physics books are Photometria
(1760) and Pyrometrie (1779).