leidoscope, which he patented; but, from some defect in the registration of the patent, it was quickly pirated, and he never realised anything by it. His 'Treatise on the Kaleidoscope ' was published in 1819.
The 'Edinburgh Magazine' was published from 1817 under the name of the 'Edinburgh Philosophical Journal,' and Brewster edited it in conjunction with Professor Jameson, the mineralogist, and afterwards alone, the name being again changed (1819) to the 'Edinburgh Journal of Science.' Not only was the number of papers published by Brewster at this period of his life remarkable, but the investigations which were required, and the discoveries especially in the delicate subject of optics which they recorded were in every way extraordinary. In 1813 he commenced to publish in the 'Philosophical Transactions' a communication 'On some Properties of Light,' and in the two succeeding years he furnished no less than nine papers on analogous subjects. After this the phenomena of double refraction engaged his attention, and his discoveries occupied several additional papers.
In 1820 Brewster became a member of the Institute of Civil Engineers in London. In 1821 he was active in founding the Royal Scottish Society of Arts, of which he was named director ; and in 1822 he became a member of the Royal Irish Academy of Arts and Sciences. In this year he edited a translation of Legendre's 'Geometry,' and also four volumes of Professor Robinson's 'Essays on Mechanical Philosophy.' In 1823 he edited Euler's 'Letters to a German Princess,' writing copious notes and a life of the author. Between 1819 and 1829 he appears to have relaxed a little, but he wrote 'On the Periodical Colours produced by Grooved Surfaces ;' he investigated 'Elliptic Polarisation by Metals,' 'The Optical Nature of the Crystalline Lens,' 'The Optical Conditions of the Diamond,' and 'The Colours of Film Plates.' Beyond these the only paper communicated to the Royal Society was one 'On the Dark Lines of the Solar Spectrum,' in which he was associated with Dr. John Hall Gladstone. In 1825 Brewster was made a corresponding member of the French Institute, and honours from all parts of the world were crowded upon him. There was never any long intermission in his researches. In 1827 he published his account of a new system of illumination for lighthouses, which led to a successful series of experiments under his direction in 1833.
In 1831 the British Association for the Advancement of Science was organised, chiefly by a few scientific men who assembled at the archiepiscopal palace near York, Brewster being among them. The first meeting was held in York, when 325 members enrolled their names. Brewster was especially active, and he strove most zealously to advance the long-neglected interests of science. In this year William IV sent to Brewster the Hanoverian order of the Guelph, and shortly afterwards an offer of ordinary knighthood followed, the fees, amounting to 109l., being remitted.
Sir David Brewster's busy pen now produced his 'Treatise on Optics' (1831) in Lardner's 'Cabinet Encyclopaedia,' a volume of 526 pages, in which every phenomenon connected with catoptrics or dioptrics known up to the time of its publication was described with remarkable clearness and precision. About the same time he wrote for Murray's 'Family Library' his 'Life of Sir Isaac Newton,' and his 'Letters on Natural Magic.' In 1855 he proved the correspondence between Newton and Pascal produced by M. Chasles to be a forgery. An accident arising through an explosion nearly robbed Brewster of his eyesight ; but his sight was eventually restored.
In 1836 Brewster went to Bristol to attend the sixth meeting of the British Association, being the guest of Mr. Henry Fox Talbot at Laycock Abbey. Mr. Talbot was engaged on his earliest experiments on photography, and his explanations of his immature processes, and the inspection of even the imperfect pictures which he produced, were sufficient to create in Brewster's mind a strong desire to work on the chemistry of light. He never found the time required for the practice of the art, but he wrote on the subject, and in 1865 received a medal from the Photographic Society of Paris.
Brewster was in receipt of an annual grant from the government of 100l. In 1836 this was increased by an additional grant of 200l. a year. In 1838 he received from the crown the gift of the principalship of the united college of St. Salvator and St. Leonard in the university of St. Andrews. This appointment relieved him from embarrassments, and he was glad to take possession of his house at St. Andrews. Brewster had published his 'Treatise on Magnetism' in the seventh edition of the 'Encyclopædia Britannica.' His labours were, however, interrupted by the illness of his wife. Her failing health caused him to remove her to Leamington, and leaving her in charge of a medical friend, he, with his daughter, attended the twelfth meeting of the British Association at Manchester, where he made the acquaintance of Dr. Dalton, which led
