Brewster, SIR DAVID, an eminent Scottish natural philosopher, was born at Jedburgh, December 11, 1781. From the early age of twelve he was educated for the Church of Scotland at the university of Edinburgh, where he highly distinguished himself. A constitutional nervousness disinclining him for a clerical life, he became editor in 1802 of the Edinburgh Magazine, and in 1808 of the Edinburgh Encyclopædia, to which he contributed many important scientific articles. Previous to this he had entered deeply on the study of optics, with which his name is now enduringly associated. The beautiful scientific toy called the kaleidoscope was invented by him in 1816, and many years after he improved Wheatstone's cumbrous stereoscope by the introduction of lenses, and produced the lenticular instrument now in use. In 1819 the Edinburgh Philosophical Journal took the place of the Magazine; and in 1831 Brewster was one of the chief originators of the British Association. In 1815 he was elected a Fellow and Copley medallist of the Royal Society; in 1816 he received half the prize bestowed by the French Institute; in 1818 the Royal Society awarded him the Rumford gold and silver medals for his discoveries on the polarisation of light; in 1825 he became corresponding member of the Institute of France; in 1832 he was knighted, and had a pension conferred upon him; in 1838 he was appointed principal of the united colleges of St Salvador and St Leonard, St Andrews; in 1849 he was elected one of the eight Foreign Associates of the French Institute; he was also a member of the academies of St Petersburg, Berlin, Copenhagen, and Stockholm. In 1859 he was chosen principal of Edinburgh University, and filled this post until within a few months of his death at Allerly, Melrose, February 10, 1868. He made important discoveries in every branch of the great subject of polarisation, and in most departments of optics, dealt with optical illusions, the colour of mother-of-pearl, fringes of colour, the optical properties of innumerable substances, biaxial crystals, dichroism, the absorption of light, phosphorescence, fluorescence, photography, and the value of combinations of lenses. The most immediate practical result of Brewster's discoveries was the introduction to British lighthouses of the dioptric system, the honour of having elaborated which he shared with Fresnel. He resolutely maintained his own theory of the three primary colours, and never fully accepted the undulatory theory of light. It has been said that he wrote with the calm decision of a philosopher, the vivid imagination of a poet, and the fervour of a preacher. In 1822 he edited Legendre's Geometry, translated by Thomas Carlyle. His Life of Newton, first published in 1828 in the Family Library, was issued in a totally new and greatly enlarged form in 1855. Among his other works are his interesting Letters on Natural Magic, addressed to Sir Walter Scott; More Worlds than One (1854); his treatises on the Kaleidoscope and on Optics (Cabinet Cyclopædia); his Martyrs of Science; and his treatises in the 7th and 8th editions of the Encyclopædia Britannica on Electricity, Magnetism, Optics, the
Stereoscope, &c. He also contributed largely to the Edinburgh and North British Reviews, and communicated hundreds of papers on scientific subjects to the transactions of learned bodies and to scientific journals. See Home Life of Brewster, by his daughter, Mrs Gordon (1869).