GERVAIS

See also:

• GERVAIS DELARUE (1751–1835)

DELARUE (1751–1835)  , French historical investigator, formerly regarded as one of the chief authorities on Norman and Anglo-Norman literature, was a native of Caen . He received his education at the university of that town, and was ultimately raised to the rank of professor . His first historical enterprise was interrupted by the French Revolution, which forced him to take refuge in England, where he took the opportunity of examining a vast mass of original documents in the Tower and elsewhere, and received much encouragement, from Sir Walter Scott among others . From England he passed over to Holland, still in prosecution of his favourite task; and there he remained till in 1798 he returned to France . The rest of his life was spent in his native town, where he was chosen principal of his university . While in England he had been elected a member of the Royal Society of Antiquaries; and in his own country he was made a corresponding member of the Institute, and was enrolled in the Legion of Honour . Besides numerous articles in the Memoirs of the Royal Society of London, the Memoires de l'Institut, the Memoires de la Societe d'Agriculture de Caen, and in other periodical collections, he published separately Essais historiques sur les Bardes, les Jongleurs, et les Trouveres normands et anglo-normands (3 vols., 1834), and Recherches historiques sur la Prairie de Caen (1837); and after his death appeared Memoires historiques sur le palinod de Caen (1841), Recherehes sur la tapisserie de Bayeux (1841), and Nouveaux Essais historiques sur la Dille de Caen (1842) . In all his writings he displays a strong partiality for everything Norman, and rates the Norman influence on French and English literature as of the very highest moment . BE LA RUE, WARREN (1815–1889), British astronomer and chemist, son of Thomas De la Rue, the founder of the large firm of stationers of that name in London, was born in Guernsey on the 18th of January 1815 . Having completed his education in Paris, he entered his father's business, but devoted his leisure DELATOR 945 hours to chemical and electrical researches, and between 1836 and 1848 published several papers on these subjects . Attracted to astronomy by the influence of James Nasmyth, he constructed in 185o a 13-in. reflecting telescope, mounted first at Canonbury, later at Cranford, Middlesex, and with its aid executed many drawings of the celestial bodies of singular beauty and fidelity . His chief title to fame, however, is his pioneering work in the application of the art of photography to astronomical research .

In 1851 his

attention was drawn to a daguerreotype of the moon by G . P . Bond, shown at the great exhibition of that year . Excited to emulation and employing the more rapid wet-collodion process, he succeeded before long in obtaining exquisitely defined lunar pictures, which remained unsurpassed until the appearance of the Rutherfurd photographs in 1865 . In 1854 he turned his attention to solar physics, and for the purpose of obtaining a daily photographic representation of the state of the solar surface he devised the photo-heliograph, described in his report to the British Association, " On Celestial Photography in England " (1859), and in his Bakerian Lecture (Phil . Trans. vol. clii. pp . 333-416) . Regular work with this instrument, inaugurated at Kew by De la Rue in 1858, was carried on there for fourteen years; and was continued at the Royal Observatory, Greenwich, from 1873 to 1882 . The results obtained in the years 1862–1866 were discussed in two memoirs, entitled " Researches on Solar Physics," published by De la Rue, in conjunction with Professor Balfour Stewart and Mr B . Loewy, in the Phil . Trans . (vol. clix. pp .

1-110, and vol. clx. pp . 389-496) . In 186o De la Rue took the photo-heliograph to

Spain for the purpose of photographing the total solar eclipse which occurred on the 18th of July of that year . This expedition formed the subject of the Bakerian Lecture already referred to . The photographs obtained on that occasion proved beyond doubt the solar character of the prominences or red flames, seen around the limb of the moon during a solar eclipse . In 1873 De la Rue gave up active work in astronomy, and presented most of his astronomical instruments to the university observatory, Oxford . Subsequently, in the year 1887, he provided the same observatory with a i3-in. refractor to enable it to take part in the International Photographic Survey of the Heavens . With Dr Hugo Muller as his collaborator he published several papers of a chemical character between the years 1856 and 1862, and investigated, 1868–1883, the discharge of electricity through gases by means of a battery of 14,600 chloride of silver cells . He was twice president of the Chemical Society, and also of the Royal Astronomical Society (1864–1866) . In 1862 he received the gold medal of the latter society, and in 1864 a Royal medal from the Royal Society, for his observations on the total eclipse of the sun in 186o, and for his improvements in astronomical photography . He died in London on the 19th of April 1889 . See Monthly Notices Roy .

Asti . Soc . I . 155; Journ . Chem . Soc. lvii . 441; Nature, xl . 26; The Times (April 22, 1889) ; Royal Society, Catalogue of Scientific Papers .