NEWS FROM HERSCHEL'S PLANET. 123 



the sun as Saturn is. So that the features of Uranus 

 are not merely reduced in seeming dimensions, in the 

 proportion of about one to four, but they are less 

 brilliantly illuminated in the same proportion. And 

 therefore (roughly) any given portion of the surface of 

 Uranus say a hundred miles square near the middle of 

 his visible disc sends to us but about one-sixteenth 

 part of the light which an equal and similarly-placed 

 portion of the surface of Saturn would send to us. 

 Now every astronomer knows how difficult it is, even 

 with very powerful telescopes, to study the physical 

 features of Saturn. A telescope of moderate power will 

 show us his ring-system and some of his satellites ; but 

 to study the belts which mark his surface, the aspect of 

 his polar regions, and in particular those delicate tints 

 which characterise various portions of his disc, requires 

 a telescope of great power. It will be understood, 

 therefore, that in the case of Uranus, which receives so 

 much less light from the sun, and is so much farther 

 from us, even the best telescopes yet made by man must 

 fail to reveal any features of interest. We may add 

 also that Uranus is a much smaller planet than Saturn, 

 though far larger than the combined volume of all the 

 four planets, Mars, Venus, the Earth, and Mercury. If 

 Saturn (without his rings) and Uranus were both visible 

 together in the same telescopic field (a circumstance 

 which may from time to time happen) the Herschelian 

 planet would appear so small and faint that it might 

 readily be taken for one of Saturn's moons, the ringed 



