306 THE WORLD MACHINE 



been predicted and calculated as the consequence of some law, 

 or a long series of observations. It was purely an accident, 

 made, moreover, by means of a relatively small telescope. It 

 undoubtedly would have been made by some other observer, 

 probably within a few years, since star maps were coming into 

 fashion more and more ; the changing position of the planet 

 must have soon been noted. 



But what the discovery did was to lift from poverty and 

 obscurity one of the most wonderful observing geniuses known 

 in the history of astronomy. This was Herschel ; his larger 

 deeds were in the realms of stellar research, and they will fill 

 a sequent chapter. Simple and loyal subject that he was, 

 Herschel claimed the right of discovery, and wished to name the 

 planet after his king, George III. The continentals did not 

 take to the suggestion ; some of them wished to name it after 

 Herschel himself, and so for a time it was known. Finally 

 it was agreed to draw a name from the ancient myths, like 

 those of the other planets, and deeming that Uranus may have 

 been the earliest of the astronomers, it perpetuates his twilight 

 fame. 



The new planet was in no wise remarkable, save as to its 

 distance. It was only about half the diameter of its neighbour 

 Saturn, though seventy or eighty times the volume of our pigmy 

 earth. One peculiarity of its distance was promptly noted ; 

 just as with most of the planets, its orbit lay at about twice the 

 distance from the sun as that of its next nearest neighbour. 

 Saturn is at ten times the distance of the earth ; Uranus was 

 found to be very closely twenty times. Promptly the astrono- 

 mers began to search for yet further outlying members of the 

 system. 



The probable existence of at least one more planet was borne 

 in by the curious discrepancies observed in the orbit of Uranus. 

 The discovery of this conjectured planet was one of the greatest 

 triumphs, though not the final, of Newton's ideas. Before it 

 could be made there was another, or rather a series, of not 

 less interest. 



Even in the solar system as it was known before Herschel, 

 there was a curious gap. If the distance of Mercury from the 

 sun be taken as unity, it was noted that Venus was very nearly 

 twice this distance, and that each successive planet was some- 

 thing like double that of the next. The relationship is not 



