COSMIC PHILOSOPHY 



that the velocities of the planetary rotations 

 supply further confirmation ; for " other things 

 equal, a genetic ring that is broadest in the 

 direction of its plane will produce a mass ro- 

 tating faster than one that is broadest at right 

 angles to its plane ; " and accordingly Jupiter 

 and Saturn, originating from relatively quoit- 

 shaped rings, rotate very swiftly ; while all the 

 inner planets, originating from relatively hoop- 

 shaped rings, rotate with much less rapidity. 



Here we may profitably consider the singular 

 instance in the history of the solar system in 

 which a detached ring has failed to become in- 

 tegrated into a single planetary mass. Every 

 one remembers how, in accordance with the law 

 of Titius concerning planetary intervals, Kepler 

 was led to predict the existence of a planet be- 

 tween Mars and Jupiter ; and how, at the be- 

 ginning of the present century, not one only, 

 but four such planets, were suddenly discovered. 

 More than a hundred of these little bodies have 

 now been detected, and each year adds new 

 names to the list. The four earliest observed — 

 Vesta, Juno, Ceres, and Pallas — are of respect- 



And concerning the Uranian system our knowledge is still 

 more inadequate. It will be observed, however, that even 

 the facts here fragmentarily collated point clearly to some com- 

 mon mode of genesis for both planets and satellites ; and are 

 likely, when completely generalized, to yield important testi- 

 mony in behalf of the nebular theory. 

 268 



