SHOOTING STARS. 273 



believs that farther observations carefully directed to this point will 

 reveal many striking similitudes. But it must be considered that a 

 shower of the same meteors coming from space with say a three 

 months' interval must sensibly change their appearances, because the 

 earth which at the first display is moving almost directly towards the 

 meteor system, is at the second display passing through it at right 

 angles. Thus the later fragments will move apparently slower, 

 and this difference of motion will originate differences in the aspect 

 or appearance of the meteors themselves. We obviously 

 require many further and careful observations, and when we have 

 them before us, I am confident we shall find there are two, at least, 

 distinct kinds of meteor showers. There will be the periodical 

 showers, amongst which the August meteors (called the Perseids) 

 and November meteors (called the Leonids) will figure the most 

 prominently. But we also have instances of this class in the meteors 

 of January 2, April 20, October 18, Nov. 27, and December 11. 

 They form a special order of systems remarkable (r) for great 

 intensity ; (2) for short endurance ; and (3) probably for radiant 

 points showing a rapid change in their apparent places amongst 

 the stars. And we shall find that there is another class of showers, 

 forming by far the most numerous order, with the distinguishing 

 characteristics of (i) giving few meteors 5 (2) long duration, and 

 (3) a stationary radiant point. The latter kind give little indication 

 of very active transient displays. Their period of action is spread 

 over a long interval, during which a feeble and intermittent fall of 

 meteors is continued. There is a very large number of these latter 

 showers, in fact the great majority of those contained in our 

 catalogues are of this sort, and it now remains for observers to 

 ascertain the exact limits of duration. It is to these long continued 

 and stationary radiants that I attribute second outbursts ; and if 

 these re-appearing meteor showers are anything beyond mere 

 chance coincidences and have a real existence, it would seem tha^ 

 they must belong to the earth. They may be of terrestrial origin, 

 but do not exist in the upper strata of the atmosphere. Such an 



