18 A Sijnopsh of the principal 



The ecceniric'iLy of his orbit is -0562 ; half ihe major axis 

 being taken as unity. 



His mean longitude at the commencement of the present 

 oentnry, was inV lo° 20' 31 ',5. 



The lonsiitudc of his perllielion was, at the same time, nx 

 2* 29" 8' 37",9: but t!)c line of the apsides has an apparent 

 motion in longitude, according to the order of the signs, of 

 J' 9',5 in a vear, or l" 5b' 47",1 in a century. 



His orbit is in-cVnied to the plane of the ecliptic in an 

 angle of 2^ 29' 3S', 1 : which is observed to decrease about 

 15", 5 in a century. 



His orbit, at the commencement of the present century, 

 crossed the eclijuic in 3^ 21° 5 a' 46'',3 : but the place of 

 the nodes has an apparent motion in longitude, according 

 to the order of llic signs, of 'i7"j'l in a year, or 45' 43'',5 iu 

 a century. 



The rotation on his axis is performed in 10*' 16' 19", 2: 

 [ai d ihe axis is inclined in an angle of 58° 41' to the plane 

 of the ecliptic] 



[His mean diameter is 7OO68 miles: consequently he is 

 nearly 10 times as larae as our Earth.] 'fhe ajis of his 

 poles is to his equatorial diaineler as 1 I to 12. 



His mass, compared with that of the Sun considered as 

 unity, is tWt.-ov- [^^'^ h'^ density is -OS.] 



[The proportion of light and heat received from the Sun 

 is -001 1 ; that received by the Earth being considered as 

 unity.] 



Saturn is sometimes marked by zones or belts ; which 

 are probably obscurations in his atmospkcre. And he is 

 accompanied by seven saieU'iles. 



The most singular pliaiiionienon, however, attending this 

 planet, is the double ring with which he is surrounded. 



This ring, which is very thin and broad,' is incbned to 

 the plane of the ecliptic in an angle of 31-' 19' 12',0; and 

 revolves from west to east, in a period of 10'' 29'- 16', 8, about 

 an axis perpendicular to its plane and passing through the 

 cenire of the planet. 



The breadth of the ring is nearlv equal to its distance from 

 the surface of Saturn : that is, about -j- of the diameter of 

 the planet. 



The surface of the ring is separated in the middle by a 

 black concentric band, which divides it into two distinct 

 rings. 



The edges of this ring, being very thin, sometimes disap- 

 pear : and, as this edge will present itself to the Sun twice 

 in each revolution of the planet, it is obvious that the dis- 

 appearance 



