120 ROUGH WAYS MADE SMOOTH. 



called their attention to the great display of November 

 meteors which might be expected on November 13-14, 

 1866. The fine shower of that year was well observed, and 

 the part we may almost say the point of the constellation 

 Leo from which the meteors radiated was correctly de- 

 termined. And now a strange thing happened. Those who 

 believed in Schiaparelli's account of the August meteors 

 supposed of necessity that the bodies forming that system 

 travel in an orbit of enormous extent, for the comet of 1862 

 travels on a path extending much further from the sun than 

 the path of Neptune. There was, therefore, nothing to 

 prevent them from believing that the Leonides travel in a 

 track carrying them far away from the sun. The recurrence 

 of great displays of these meteors at intervals of about 33 

 years might be readily explained on such an assumption, 

 for if the Leonides have a period of about 33 years, their 

 path must extend far beyond the path of Uranus. But 

 hitherto astronomers had not been ready to admit such an 

 explanation of the periodic recurrence of great displays of 

 the November meteors. They preferred theories (for 

 several were available) which accounted for the 33-year 

 period, while assigning to the Leonides paths of much less 

 extent. Now that the idea of vast meteoric orbits had been 

 fairly broached, some astronomers thought it might at least 

 be worth while to calculate the path of the November 

 meteors on the assumption that their true period is about 

 33i vears - This was perfectly easy, because the period of 

 a body travelling round the sun determines the velocity at 

 any given distance from the sun, and knowing thus (at 

 least, on this assumption) the true velocity of the Leonides 

 as they rush into our air, while their apparent path is 

 known, their true course is as readily determined as the true 

 course of the wind can be determined by a seaman from the 

 apparent direction and velocity with which it reaches his 

 ship. When the path of the November meteors had been 

 determined (on the assumption mentioned), it was found to 

 be identical with the path of a comet which had only been 



