Page:The American Cyclopædia (1879) Volume XIV.djvu/665

 SATURN the two bright rings is constantly increasing." The theory now generally accepted respecting the rings is that they are composed of minute satellites, like sand on the seashore for multi- tude. The following table shows the position of the ring system and the proportions of the ring and globe : Longitude of ring's rising node 167 44' Inclination of ring to the ecliptic 28 10' Annual precession of rising node 8-145" Exterior diameter of outer ring in miles 166,920 Interior " " ' " 147,670 Exterior diameter of inner ring 144,810 Interior " * " 10i,100 Inferior diameter of the dark ring 91,780 Breadth of outer bright ring 9,625 of inner bright ring 17,605 " of division between rings 1,680 of dark ring 8,660 of system of bright rings 28,910 " of entire system of rings 87,570 Space between planet and dark ring 10,822 Saturn is attended by eight satellites, the largest of which, Titan, sixth in order of dis- tance from the planet, is the largest satellite of the solar system, and probably is as large as the planet Mercury. Much confusion prevails, as Sir John Herschel complains, in the nomen- clature of the Saturnian satellites, owing to the order of distances not coinciding with that of discovery. The elements of the satellites, and the names of their discoverers, are as follows, counting from within outward : No. Sidereal revolution. Distance In radii of > . Diameter In miles. Discoverer. 1. Od. 22h. 87m. 8-3607 1,000? Sir W. Herschel. a. 1 8 53 4-8125 do. 8. 1 21 18 5-3396 500? Q. D. Oassini. 4. 2 17 41 6-8898 500? do. 5. 4 12 25 9-5528 1,200 do. 6. 15 22 41 22-1450 8,000 C. Huygens. 7. 21 7 8 26-7834 ? W. Bond. 8. 79 7 54 64-3590 1,800 G. D. Cassini. Saturn's surface is marked by belts, somewhat similar to Jupiter's. Owing to the inclination of Saturn's equator, his belts afforded an op- portunity, wanting in Jupiter's case, for testing the question whether the sun is the chief agent in causing the belts. It is clear that if this were so the belts would follow the sun, the equatorial zone, a well marked band of whitish color, remaining no longer equatorial when the sun was far to the north or south of the Satur- nian celestial equator. And as the sun viewed from Saturn takes more than 29 years in com- pleting the circuit of the star sphere, being half that time north of the Saturnian equator and the remaining half south of that circle, it is clear that there would be ample time for the sun to draw the cloud zone north of Saturn's equator during the summer of Saturn's north- ern hemisphere, and south of the equator du- ring the summer of Saturn's southern hemi- sphere. This would happen if the sun caused and therefore ruled the Saturnian cloud belts, as he causes and rules the great cloud belt of the zone of calms. But in Saturn's case nothing of this kind is observed. His great SATURNALIA equatorial cloud zone remains equatorial all the year round. No clearer evidence could be desired of the fact that this cloud zone is neither sun-raised nor sun-ruled, but is due to some cause in the Saturnian globe itself. This cause can be no other, it would seem, than an intense heat pervading the whole globe of the planet. For other reasons, drawn from a con- sideration of the condition of Jupiter and Sat- urn on the nebular hypothesis, Prof. Peirce has recently adopted the opinion that these two great planets are thus instinct with their primeval fires. Measurements of Saturn have led to the singular result that the planet ap- pears to vary in shape. The disk is usually elliptical, but sometimes shows a figure in which the two diameters from 45 Saturnian latitude N. to 45 S. appear the greatest, the equatorial diameter less, and the polar diame- ter the least. This appearance has been called Saturn's " square-shouldered " aspect. It was first noticed by Sir W. Herschel, and as he recognized it with different telescopes he was satisfied that it was not a mere optical delusion. It has since been noticed by other observers, as the Bonds, Airy, and Coolidge, who possessed far too great skill in observing to be readily deceived in a matter so simple. It has "been ascribed to optical illusion, but probably with- out sufficient ground. In fact it has never been shown why the illusion should be noticed at one time and not at others, or how it can be occasioned. It appears to the writer that a sufficient, a reasonable, and a probable inter- pretation is afforded by the theory that the atmosphere of Saturn is subject to changes, either by the formation and precipitation of cloud masses at an enormous elevation, or in some other way, which cause the apparent fig- ure of the disk to alter while the real globe of Saturn, far within the visible boundary, re- mains unchanged in shape. This theory cor- responds well with results to which the study of the planet Jupiter seems to lead us, as already shown. (See JUPITEB.) SATIRXALIA, the festival of Saturn, celebra- ted originally by the rural population of ancient Italy in December, as a sort of harvest home, and in later ages converted into a season of almost absolute relaxation and merrymaking. Its origin was ascribed to Janus, Hercules, and others. Tullus Hostilius is said to have revived games of the Saturnalia and Opalia at Rome, in honor of Saturn and Ops, to commemorate a victory over the Sabines. During the repub- lic a single day in the middle of December was set apart for its celebration, although the whole month was considered as dedicated to Saturn ; but under the emperor Augustus the term was made to embrace Dec. 17, 18, and 19, to 'which a fourth day, and under Caligula a fifth, was added. It would seem, however, that under the emperors the festivities in real- ity lasted seven days, and included three sep- arate festivals, the Saturnalia proper, the Opa- lia, and the Sigillaria, so called from the little