Manchester Memoirs, Vol. Iv. (1910), No. I. 15 



interior of the planet as being the birthplace of these 

 singular appendages. It is therefore with some amount 

 of diffidence that 1 venture to affirm that they are the 

 ejectamenta of Saturn when its diminishing energies were 

 insufficient to eject a cometary satellite, or a comet with 

 its train of meteorites beyond the sphere of its gravita- 

 tional attraction. And here it may be well to remark 

 that all meteoric and other small discrete bodies are not 

 formed directly from the universal nebular substance, but 

 are necessarily fragments of the solid or liquid parts of a 

 globe, which had a long previous history, involving the 

 evolution of the several series of elementary substances of 

 which the globular body was composed. 



The dimensions of Saturn's rings are drawn up in the 

 following table for a new determination of the times of 

 their revolutions, and are based upon the commonly 

 accepted equatorial diameter of the planet = 73.860 miles 

 or the semi-diameter of 36,930 miles. 



The dimensions have been calculated from scaled 

 measurements which I have made of reproductions of the 

 fine photographs of Saturn taken at the Lick* and other 

 Observatories during recent years, and which surpass in 

 accuracy those calculated from observations and micro- 

 metric measurements. 



The radial dimensions of the rings on the line of the 

 equatorial diameter of the planet have the same propor- 

 tional relations at different angles about this diameter, 

 and constitute the basis of the method of measurements 

 which I have adopted. 



In accordance with the notation of O. Struve, now 

 generally adopted, I have designated the rings A, B, and 

 C, in the order of their distances from the planet. 



* Todd, "Stars and Telescopes," 1900. 



