56 HISTORY OF ASTRONOMY. 



If the distance of the Earth from the Sun be called 

 10, then 4 will represent nearly the distance of Mercury ; 

 7 that of Yenus j 16 that of Mars ; 52 that of Jupiter; 

 and 100 that of Saturn. This law exhibited in a striking 

 light the abrupt leap from Mars to Jupiter, and sug- 

 gested the probability of a planet revolving in the inter- 

 mediate region. This conjecture was rendered still more 

 plausible by the discovery, in 1781, of the planet Uranus, 

 whose distance from the sun was found to conform 

 nearly with the law of Bode. In Germany, especially, 

 a strong impression had been produced that a planet 

 really existed between Mars and Jupiter, and the Baron 

 de Zach went so far as to calculate, in 1784-5, the orbit 

 of the ideal planet, the elements of which he published 

 in the Berlin Almanac for 1789. In 1800, six astron- 

 omers, of whom the Baron was one, assembled at Lilien- 

 thal, and formed an association of twenty -four observers, 

 having for its object to effect the discovery of the unseen 

 body. For this purpose the zodiac was divided into 

 twenty-four zones, one of which was to be explored by 

 each astronomer ; and the conduct of the whole opera- 

 tion was placed under the superintendence of Schroter. 

 Soon after the formation of this society, the planet was 

 discovered, but not by any of those astronomers who 

 were engaged expressly in searching for it. Piazzi, the 

 celebrated Italian astronomer, while engaged in construct- 

 ing his great catalogue of stars, was induced carefully to 

 examine, several nights in succession, a part of the con- 

 stellation Taurus, in which "Wollaston, by mistake, had 



