fcH. xxxn. METEOR-SHOWERS. 309 



The next was that of the November meteors, which was 

 determined by Adams, and also independently by Leverrier. 

 It had been shown by searching out all the past accounts 

 of November showers that in times gone by the earth passed 

 through these meteors a little earlier in the year than she 

 does now, and this could not be accounted for by any irre- 

 gularity in the movement of the earth. It looked therefore 

 as if the orbit of the November meteors must be slowly 

 shifting, just as the orbits of the planets do, within certain 

 limits. It was upon this shifting that Adams founded his 

 calculations, and he worked out the meteor path with great 

 accuracy, showing that those astronomers had been right 

 who thought it extended beyond Uranus. This time the 

 problem was solved by pure astronomical reasoning, but per- 

 haps the most remarkable part of the story is that in 1866, 

 long after Adams had determined the orbit, a new comet 

 was seen, which was found to move exactly along the path 

 of the November meteors, in the same way that the comet 

 of 1862 agrees with those which fall in August. 



Although these two meteor-showers are the most import- 

 ant, they are by no means the only ones crossed by our 

 earth. Mr. Proctor states that on any clear night, if you 

 watch carefully, you may see about six shooting-stars in one 

 hour ; and Professor Newton, of America, has calculated 

 that 7,500,000 meteors large enough to be seen without a 

 telescope pass through our atmosphere in one single day 

 and night At least a hundred sets of meteors, or meteor- 

 systems as they are called, are known to astronomers, and 

 each one of these is composed of millions of bodies ; and 

 you must bear in mind that these systems do not move 

 round us, but round the sun, so that it is only because we 

 happen to cross their path that we know anything of them. 

 It would be idle to suppose that these hundred meteor- 



