116 COSMOS. 



zur Ke?intniss des gestirnten Himmels, that " he had taken 

 the law of the distances from a translation of Bonnet's Con- 

 templation de la Nature, prepared by Professor Titius at 

 Wittenberg," still it has generally borne his name, and sel- 

 dom that of Professor Titius. In a note which the latter add- 

 ed to the chapter on the System of the Universe,* he says, 

 " When the distances of the planets are examined, it is found 

 that they are almost all removed from each other by distances 

 which are in the same proportion as their magnitudes in- 

 crease. If the distance from Saturn to the Sun is taken as 

 100 parts, the distance of Mercury from the Sun is 4 such 

 parts, that of Venus 4 + 3 = 7 such parts, the Earth 4 + 6 = 10, 

 Mars 4+12 = 16. But from Mars to Jupiter there is a de- 

 viation from this accurate (!) progression. Mars is followed 

 by a space of 4+ 24 = 28 such parts, in which neither a prin- 

 cipal planet nor a subordinate planet has yet been seen. Is 

 it possible that the Creator should have left this space empty ? 

 It can not be doubted that this space belongs to yet undis- 

 covered satellites of Mars ; or that perhaps even Jupiter has 

 further satellites around him, which have not hitherto been 

 seen by any telescope. In this space (unknown to us as re- 

 gards its contents) Jupiter's circle of action extends to 4 + 48 

 = 52. Then follows Saturn in 4 + 96 = 100 parts — an ad- 

 mirable proportion." Titius was therefore inclined to consid- 

 er the space between Mars and Jupiter as containing, not 

 one, but, as is actually the case, several cosmical bodies ; how- 

 ever, he conjectured that they were more likely to be subor- 

 dinate than principal planets. 



How the translator and commentator of Bonnet obtained 

 the number 4 for the orbit of Mercury, is nowhere stated. 

 Perhaps he selected it only in order to have in combination 

 with the easily divisible numbers 96, 48, 24, &c, exactly 100 

 for Saturn, at that time the most distant planet known, whose 

 distance is 9-5, thus very nearly =100. It is less probable 

 that he constructed the order of succession by commencing 

 from the nearer planets. A sufficient correspondence of the 

 law of duplication, setting out, not from the Sun. but from 

 Mercury, with the true planetary distances, could not have 

 been affirmed in the last century, as the latter were known 



* Karl Bonnet, Betrachtung iiber die Nat?ir, translated by Titius, sec- 

 ond edition, 1772, p. vii., note 2 (the first edition appeared in 1766). In 

 Bonnet's original work no such law is noticed. (Compare also Bode, 

 Anleit. zur Kenntniss des gestirnten Himmels, second edition, 1772, p, 

 462.) 



