loss of appendages so brilliant and unique as the rings. Saturn's train of satellites is the most numerous and remarkable in our system. As already mentioned, Huygens, the discoverer of the true form of the ring, discovered also the first and brightest satellite, Titan, which is a body somewhat larger than our own moon, having a diameter of 2,720 miles. A few years later came Cassini's discoveries of four other satellites, beginning in 1671 and ending in 1684. For more than 100 years discovery paused there, and it was not until August and September, 1789, that Sir William Herschel added the sixth and seventh to our knowledge of the Saturnian system. In 1848 Bond in America and Lassell in England made independently the discovery of the eighth satellite--another of the coincidences which marked the progress of research upon Saturn, and in both of which Bond was concerned. Then followed another pause of fifty years broken by the discovery, in 1898, by Professor Pickering, of a ninth, whose existence was not completely confirmed till 1904. The motion of this satellite has proved to be retrograde, unlike that of the earlier discovered members of the family, so that its discovery has introduced us to a new and abnormal feature of the Saturnian system. The discoverer of Ph[oe]be, as the ninth satellite has been named, has followed up his success by the discovery of a tenth member of Saturn's retinue, known provisionally as Themis. Accordingly the system, as at present known, consists of a triple ring and ten satellites. The last discovered moons are very small bodies, the diameter of Ph[oe]be, for instance, being estimated at 150 miles; while its distance from Saturn is 8,000,000 miles. From the surface of the planet Ph[oe]be would appear like a star of fifth or sixth magnitude; to observers on our own earth its magnitude is fifteenth or sixteenth. The ten satellites have been named as follows: 1, Titan, discovered by Huygens; 2, Japetus; 3, Rhea; 4, Dione; 5, Tethys, all discovered by Cassini; 6, Enceladus; and 7, Mimas, Sir William Herschel; 8, Hyperion, Bond and Lassell; 9, Ph[oe]be; and 10, Themis, W. H. Pickering. Titan, the largest satellite, has been found to be considerably denser than Saturn himself.