The first, whom Lord Kelvin considers “the most accomplished and original naturalist of his time,” was a pupil of Geoffroy Saint-Hilaire, Jussieu, and De Blainville. He is regarded as the originator of the use of the dredge for collecting specimens and the first who undertook the systematic study of Marine Zoology with reference to the distribution of fauna. In 1859 his _Natural History of the European Seas_ appeared after his death. One of the most important investigators in this line is Prof. Haeckel, famous for his studies of the lower class of marine animals. He is also distinguished for his researches in other branches of Zoology and Palæontology, and was one of the first followers of Darwin in Germany. Entomology has also made enormous progress during the Nineteenth Century. At the end of the Seventeenth Century, Ray estimated the number of insects throughout the world at 10,000 species! The great entomologists of the Eighteenth Century include Linnæus, De Geer, and Fabricius. Next follow Latreille, Kirby and Spence, and a host of distinguished scientists in Europe and the United States, of whom Sir John Lubbock (Lord Avebury) heads the list. A comparatively new line of investigation is that of the Chalcididæ (see Fairy Flies, pages 1449-1458, in Vol. IV). ESTHER SINGLETON. ILLUSTRATIONS The Zodiacal Light _Frontispiece_ Chart of the Northern Constellations _Opposite p._ 73 Belt and Sword of Orion ” 121 Nebula in the Constellation Cygnus ” 169 Sun’s Surface and Sun Spot ” 217 Portion of the Moon’s Disk ” 265 Nine Views of the Hour-Glass Sea on Mars ” 313 Twelve Views of Jupiter ” 361 Three Views of Saturn ” 409 CONTENTS THE HEAVENS. Amédée Guillemin 25 SPACE. Richard A. Proctor 33 EXTENT OF THE SIDEREAL HEAVENS. Sir Robert S. Ball 42 THE STARS. Amédée Guillemin 53 THE LUCID STARS. J. E. Gore 60 THE CONSTELLATIONS. Camille Flammarion 70 THE ARABIAN HEAVENS. Ludwig Ideler 106 ASTRONOMY WITHOUT A TELESCOPE. J. E. Gore 120 THE MILKY WAY. Richard A. Proctor 133 THE MAGELLANIC CLOUDS—ZODIACAL LIGHT—STAR GROUPS. Amédée Guillemin 147 THE NEBULÆ AND SWARMS OF SUNS. J. E. Gore 154 THE GREAT NEBULA OF ORION. Sir Robert S. Ball 176 COLORED, DOUBLE, MULTIPLE, BINARY, VARIABLE, AND TEMPORARY STARS. J. E. Gore 187 A WORLD ON FIRE—NOVA PERSEI. Alexander W. Roberts 228