THE NOVEMBER METEORS. 113 



remain in great part solid until they actually strike the earth 

 itself. 



The importance of the meteors in the planetary system 

 will be recognised when wo remember that the November 

 group alone extends along its oval course in one complete 

 system of meteors for a length of more than 1,700 millions 

 of miles, with an average thickness of about a million 

 miles (determined by noting the average time occupied 

 by the earth in passing through the system on November 

 13-14), and an unknown cross breadth which probably does 

 not fall short of three or four millions of miles. Other 

 systems are, no doubt, far more important, for it has been 

 found that meteors follow in the track of comets. Now the 

 November meteors follow in the track of a comet (Tempel's 

 comet of 1866), which was so small when last favourably 

 placed for observation that it escaped detection by the naked 

 eye. If so small a comet as this is followed by so large 

 a meteoric system, in which also meteors are strewn so 

 richly that during the passage of the earth through it, tens 

 of thousands of meteors have been counted, how vast must 

 be the numbers and how large probably the individual 

 bodies following in the track of such splendid comets as 

 Newton's, Donati's (1858), the comets of 1811, 1847, 1861, 

 and others ! For it should be remembered that we become 

 cognisant of the existence of a meteoric system only when 

 the earth threads its way through one, when those which 

 she encounters may become visible as falling stars if it so 

 chances that she encounters them on the dark or night half 

 of her surface. But the earth is far smaller compared with 

 a system like the November meteor-flight than a rifle-ball 

 compared with the largest flight of birds ever yet seen. 

 Such a ball fired into a very dense and widely extending 

 flock of birds might encounter here and there along its 

 course some five or six birds not one in 10,000, perhaps, 

 of the entire flight ; and if the flock continued flying with 

 unchanging course, a hundred rifle balls might be fired 

 through it without seemingly reducing its numbers. Our 



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