ro; 



Dr. H. Wilde on the Origin of 



revolutions, and are based upon the commonly accepted 

 equatorial diameter of the planet = 73,860 miles or the semi- 

 diameter of 36,930 miles. 



Elements of Saturn's Rings. 



Ri 



Distance from centre 

 of Saturn. 



Sat. Units. 



Miles. 



Time of 

 Revolution. 



Exterior A 230 



Breadth 026 



Mid-breadth 217 



Interior A 21)4 



Interval O07 



Exterior B 1'97 



Breadth | 047 



Mid-breadth } 1'735 



Interior B ; 1 50 



Exterior C j 1*50 



Breadth ! 123 



Mid-breadth , - 1385 



Interior C \ T27 



Ball Space \ 0-27 



Sat. Ball ! 1-00 



Mimas 3 - 36 



84.937 



9,602 

 80.138 

 75,337 



2,585 

 72.752 

 17,357 

 64.073 

 55,395 

 55,395 



8,493 

 51,148 

 46,901 



9,971 

 36,930 



124,084 



12 48 



11 45 



10 42 



10 9 



8 



24 



6 



44 



6 



44 



»» 



»> 



6 



00 



5 



15 



») 



*. 



10 



13 



22 



37 



The dimensions have been calculated from scaled measure- 

 ments which I have made of reproductions of the fine photo- 

 graphs of Saturn taken at the Lick * and other observatories 

 during recent years, and which surpass in accuracy those 

 calculated from observations and micrometric measurements. 



The radial dimensions of the rings on the line of the 

 equatorial diameter of the planet have the same proportional 

 relations at different angles about this diameter, and con- 

 stitute the basis of the method of measurements which I 

 have adopted. 



In accordance with the notation of 0. Struve, now generally 

 adopted, I have designated the rings A, B, and C in the 

 order of their distances from the planet (PI. XIY. fig. 2). 



* Todd, • Stars and Telescopes/ 1900. 



