AN EVENING WITH THE TELESCOPE. 117 



of a somewhat fainter description, of which one at least, 

 in the outer ring, is a permanent feature of the system. 



To see the most delicate part of this beautiful structure 

 requires a telescope of considerable power ; it has only been 

 discovered in comparatively recent years, and is the third 

 ring of the system. It extends from the inner margin 

 of the second ring, half-way in towards the globe of 

 the planet. The name assigned to this mysterious but 

 lovely object is the crape ring, and the appropriateness 

 of the designation will be apparent when the hue of 

 the object as well as its curious semi-transparency is 

 noticed. 



The structure of the rings of Saturn suggests problems 

 that have exercised the profoundest mathematicians. It 

 was speedily seen that the rings could not be thin plates 

 of solid material. No doubt a superficial glance at their 

 appearance will suggest that such is their nature. How- 

 ever, it can be demonstrated by mechanical principles that 

 the very existence of the rings would be impossible if 

 they were what this notion implies. In this instance, 

 as in many others, the pen of the mathematician has 

 proved a more potent instrument than the telescope. 

 What the astronomer could hardly expect to find out in 

 his observatory has been demonstrated by actual calcula- 

 tion made by pen and paper. It has been proved that 

 this wondrous set of rings consists of a multitude of small 

 objects, each pursuing its own voyage round the planet 

 like a little moon. These bodies are so numerous and so 

 close together that the most powerful telescope can hardly 

 be said to recognise their individual existence, though 

 occasionally no doubt the rings do seem subdivided in a 



