DIMENSIONS OF SATURN S RINGS. 



following table are given the results of the micrometric observa- 

 tions of Professor Struve, reduced to the mean distance. 



The relative dimensions of the two rings, and of the planet 

 within them, are represented in fig. 8 projected upon the common 

 plane of the rings and the planet's equator. Each division of 

 the subjoined scale represents 5000 miles. 



9. The most surprising result of recent telescopic observations 

 of this planet has been the discovery of a ring, composed, as 

 it would appear, of matter reflecting light much more imperfectly 

 than the planet or rings already described ; and, what is still 

 more extraordinary, transparent to such a degree that the body 

 of the planet can be seen through it. 



In 1838, Dr. Galle, of the Berlin observatory, noticed a phe- 

 nomenon, which he described as a gradual shading off of the 

 inner ring towards the surface of the planet, as if the solid 

 matter of the ring were continued beyond the limit of its 

 illuminated surface, this continuation of the surface being 

 rendered visible by a very feeble illumination, such as would 

 attend a penumbra upon it ; and measures of this obscure 

 surface were published by him in the " Berlin Transactions " of 

 that year. 



The subject, however, attracted very little attention until 

 towards the close of 1850, when Professor Bond, of Boston, and 

 Mr. Dawes, in England, not only recognised the phenomenon 

 noticed by Dr. Galle, but ascertained its character and features 



55 



