520 COSMOS. 



but these lines or stripes have never been constant. Very 

 recently, during the latter months of the year 1850, a third very 

 pale, feebly luminous, and darker ring, has been discovered 

 between the planet and the ring hitherto called the inner one. 

 The discovery was made nearly simultaneously by Bond, at 

 Cambridge (U. S.), on the llth of November, by means of 

 the great refractor of Mertz with a four teen-inch object-glass, 

 and by Dawes, near Maidstone, on the 25th of November. 

 This ring is separated from the second by a black line, and 

 occupies the third part of the space, between the second ring 

 and the body of the planet, which was formerly stated to be 

 vacant, and through which Derham affirmed that he saw small 

 stars. 



The dimensions of the divided ring of Saturn have been 

 determined by Bessel and Struve. According to the latter, 

 the exterior diameter of the outer ring, at Saturn's mean 

 distance, appears to us under an angle 40" 09, equal to 1 53,200 

 geographical miles; the interior diameter of the same ring 

 under an angle of 35"'29, equal to 134,800 geographical miles. 

 For the exterior diameter of the inner (second) ring is 

 obtained 34"'47 ; for interior diameter of the same ring 26"-67. 

 Struve fixes the space between the last-mentioned ring and 

 the surface of the planet at 4"*34. The entire breadth of the 

 first and second rings is 14,800 miles ; the distance of the rings 

 from the surface of Saturn, about 20,000 ; the space which 

 separates the first from the second ring, and which represents 

 the black line of division seen by Dominique Cassini, is only 

 1,560 miles. The mass of the rings is, according to Bessel, 



T |-g- of the mass of Saturn. They present a few elevations 81 



> 



nomena which are presented by Saturn and his ring, did not 

 take place until the year 1659, four years afterwards, in the 

 Systema Saturnium. 



81 Such mountain-like inequalities of surface have recently 

 been again noticed by Lassell in Liverpool, by means of a 



