David Brewster (1781-1868), Scottish physicist, discoverer of the polarizing angle or Brewster's law. It states that light reflected from a solid surface is polarized. Originally studying for the ministry at Edinburgh University, he abandoned the church for science after graduating. His work, which amounts to almost 300 papers, includes the optical classification of crystals & minerals, and the use of spectroscopy for chemical analysis. A keen inventor, he patented his invention of the kaleidoscope in 1816. In 1831 he helped found the British Association for the Advancement of Science. Brewster was knighted in 1832 for his services to science.