1870.) on the Stori/ of the Nuvnnhrr Meteors. 47 



liavc almost grazed liis surface, and while tlicy were very close to such 

 a planet, he wonld be able to drag tlieni (piito out of tlieir former 

 course. This the planet Uranus seems to have done, and when, pur- 

 suing his own course, he again got too far off to influence them 

 sensibly, they found themselves moving slowly backwards, and slowly 

 inwards ; and accordingly began the new orbit round the sun, which 

 corresponds to the situation into which they had been brought, and 

 the direction and moderate speed of their new motion. 



They seem to have passed Uranus while they were still a small 

 compact cluster. Nevertheless those members of the grouj) which 

 happened to be next the jilanet as they swept past, would be attracted 

 with somewhat more force than the rest, the farthest members of the 

 group with the least. The result of this must inevitably have been 

 that when the group were soon after abandoned to themselves, they 

 did not find themselves so closely compacted as before, nor moving 

 with an absolutely identical motion, but with motions which differed, 

 although perhaps very little, from one another. These are conditions 

 which would have started them in those slightly differing orbits 

 round the sun, which, as we have seen, would cause them, as time wore 

 on, to be drawn out into the long stream in which we now, after 

 seventeen centuries, find them. 



What is here certain is, that there was a definite time when the 

 meteors entered upon the path they are now pursuing — that this time 

 was the end of February or beginning of March in the year 126 is still 

 a matter of probability only. It is, however, highly probable, because 

 it explains all the phenomena at present known ; but astronomers are 

 not yet in a position to assert that it is ascertained, since one link in 

 the complete chain of proof is wanting. We who live now should be 

 in possession of this link if our ancestors had made sufficiently full 

 observations ; and our posterity will have it when they compare the 

 observations they can make with those which we are now carefully 

 placing on record for their use. They will then know whether the 

 rate at which the stream is lengthening out is such as to indicate that 

 A.D. 126 was the year in which this process began. If so, Le Verrier's 

 hypothesis will be fully proved. 



MR. STONEY. 



Another episode in the eventful history of these meteors is also known 

 with considerable probability. It has been already mentioned that a 

 comet is travelling along the same path as the meteors. It is moving a 

 very little slower than they, and is at present just at the head of the 

 procession which they make through space. Another comet is similarly 

 moving in the track of the great elliptic ring of August meteors. In 

 1867, the lecturer ventured to suggest an important function which 

 these comets seem to have discharged. Picture to yourselves a mass 

 of gas before it became connected with the solar system, travelling 

 through space at a distance from the sun or any other star. Meteors 



