THE TWO COMETS OF THE YEAR 1868. 179 



Uranus. And the period of this orbit was calculated 

 to be 33^ years. Here then was strong confirmatory 

 evidence in favour of the elliptic orbit and the long 

 period assigned, by way of assumption, to the August 

 meteors. But this was far from being all. Astrono- 

 mers looked for a comet to be associated with the 

 November meteors ; and they found one a small one, 

 it is true, but with a well-defined character an orbit 

 calculated beyond suspicion of important error, and 

 agreeing so closely in its motions with those of the 

 November meteors that the chances were millions on 

 millions to one against the coincidence being acci- 

 dental. It hardly required, after this, that an associa- 

 tion should be pointed out between other meteor- 

 systems and other comets. Yet this has been done, 

 and thus that which had already been demonstrated 

 was illustrated by new proofs. We may say that 

 nothing which men of science have dealt with has ever 

 been more satisfactorily proved than the fact that 

 meteors are the attendants on comets. 



Now, how meteors are thrown off from cometic 

 nuclei we are not yet able to say. They differ wholly 

 in character from their source, and thus we learn that 

 the gaseous nature of cometic nuclei is due to the 

 action of causes connected with those to which the 

 nuclear (structure of the comet's head is due. But 

 whether the first formation of meteoric systems is asso- 

 ciated in any way with the processes which result in 

 the formation of a comet's tail, is not quite so clear. 

 As yet no comet which has had a brilliant tail has been 



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