DREYER, JOHN LOUIS EMIL Danish astronomer, was born at Copenhagen on Feb. 13, 1852, and was I educated in his native town. In 1874 he became astronomer at the earl of Rosse's observatory at Birr Castle, Ireland. He re mained in Ireland, holding the post of assistant astronomer at the Royal Observatory, Dunsink, from 1878 to 1882, and of di rector of the observatory at Armagh from 1882 until he retired in 1916. Dreyer's work in astronomy falls into two groups—his observations on nebulae and on the motion of stars, and his work on the history of astronomy. His astronomical observations were started at the Rosse observatory, where the telescope was par ticularly suitable for his purposes, and continued at Dunsink and Armagh. Dreyer is the author of a number of papers on nebulae and stars, and of Second Armagh Catalogue of 3,300 Stars (1886) . His "New General Catalogue of Nebulae and Clusters of Stars," published in the Memoirs of the Royal Astronomical Society (1888), with supplements in and 1908, is a standard work. He was particularly interested in the work of Tycho Brahe, and wrote Tycho Brake, a Picture of Scientific Life and Work in the 16th century (1890), and prepared a complete edition of Tycho Brake's work, Tycho Brake Opera Omnia. The first volume was published in 1913; ten volumes appeared before Dreyer's death, and the remaining four were complete in manuscript. Dreyer held many academic honours. He died on Sept. 14, 1926.