i8 6

Sir Is a ac Newton’s BookIL

volves round in about I day iihours. The next satelliteis distant about y^ semidiameters, and makes its period in a-bout a days 17^ hours. The third is removed to the dist-ance of about 8 semidiameters, and performs its revolution innear 4 days hours. The fourth satellite discovered firstby the great Huygens, is near 18^ semidiameters, andmoves round Saturn in about 1 y days 221 hours. The out-ermost is distant y 6 semidiameters, and makes its revolutionin about 79 days Jj hours \ Besides these satellites, therebelongs to the planet Saturn another body of a very singularkind. This is a shining, broad, and fiat ring, which encom-pastes the planet round. The diameter of the outermostverge of this ring is more than double the diameter of Saturn.Huygens, who first described this ring, makes the wholediameter thereof to. bear to the diameter of Saturn the pro-portion of 9 to 4. The late reverend Mr. Pound makes theproportion something greater, viz. that os 7 to 3. The di-stances of the satellites of this planet Saturn are compared byCAssini to the diameter of the ring. His numbers I havereduced to those above, according to Mr. Pound’s propor-tion between the diameters of Saturn and of his ring. Asthis ring appears to adhere no where to Saturn, so the dist-ance of Saturn from the inner edge. of the ring seems rathergreater than the breadth of the ring. The distances, which-here been given, of the several satellites, both for Jupiterand'ljkturn, may be more depended on in relation to theprop<mion, which those belonging to the lame primary planet

* Newt. Princ. philos. Lib. III. pag. 391, 391.

bear