146 A CENTURY'S PROGRESS IN ASTRONOMY. 



Further meteoric showers from Biela's comet 

 were seen in 1885 and 1892. The Leonid 

 shower was confidently predicted for 1899, in 

 accordance with the thirty -three -year period, 

 but the great display did not come off, either 

 in 1899 or 1900. In 1901 there was a certain 

 weak shower observed in America ; and similar 

 displays took place in 1903 and 1904. Many 

 explanations have been given as to the failure 

 of the shower, the most probable idea being 

 that the attraction of Jupiter diverted the 

 meteors from their course. 



Denning's observations on meteors resulted, 

 as early as 1877, in the discovery of so-called 

 "stationary radiants." The radiant-point of 

 a long enduring shower usually exhibits an 

 apparent motion, resulting from the combined 

 orbital motions of the Earth and the meteors ; 

 but Denning found that in some cases the 

 shower, though lasting for months, persistently 

 exhibited the same radiant-point, implying that 

 the motion of the Earth must be insignificant 

 compared with that of the meteors, computed 

 by Ranyard at 880 miles per second. The dif- 

 ficulty of admitting so great a velocity led 

 the French astronomer, Francois Felix Tisserand 

 (1845-1896), to doubt the existence of these 

 stationary radiants ; but the fact of their 



