178 LIGHT SCIENCE FOR LEISURE HOURS. 



the interplanetary spaces, that they form systems, and 

 that these systems travel in regular elliptical orbits 

 about the sun. Two of the systems produce striking 

 meteoric displays, viz. the system encountered by the 

 earth on or about August 10, and the system encoun- 

 tered on or about November 13. Now it had been 

 suggested that the members of the former system 

 follow the track of the conspicuous comet which made 

 its appearance in the year 1862 ; and it was proved 

 that, assuming the orbit of the meteors to be very 

 eccentric, and assigning to them a period of 147 years 

 (that of the comet), their motions corresponded in the 

 most remarkable manner with the orbital track of the 

 comet. In fact the agreement was so close that very 

 few who had examined the question could believe it to 

 be accidental. But there were two objections on which 

 some stress was laid. First, it had been necessary to 

 make assumptions respecting the motion of the meteors ; 

 secondly, those assumptions were not rendered probable 

 by anything which had been proved respecting any 

 meteoric system. The examination of the November 

 star-shower by a host of eminent mathematicians in 

 1866-7 led to results which at once removed these 

 objections, and brought new evidence and that of 

 the most striking character in favour of the theory 

 that comets and meteors are associated. It had been 

 supposed that the November meteors travelled in a 

 nearly circular orbit within a period of somewhat less 

 than a year. Adams proved that they travel in an orbit 

 extending far out into space beyond the orbit of distant 



