1889.] on Meteorites and the History of the Stellar Systems. 383 



The result of tliis discussion then appeared to justify the opinion 

 that the meteoric theory may be reconciled with Laplace's hypothesis, 

 and that they may both be held to be true. 



After this discussion of the proposed modification of Laplace's 

 hypothesis, it was natural to turn to the series of events which may 

 be supposed to have occurred after the nebular stage of evolution. 



At the various centres of condensation, which now form the sun, 

 planets, and satellites, the swarm of meteorites must bo supposed to 

 have become denser, and the collisions too frequent to allow the gases 

 to condense again, so that by degrees all solid matter in the neigh- 

 bourhood of such centres would be volatilised. Away from these con- 

 densations there were still many free meteorites, but the majority of 

 those which formed the swarm in primitive times would have been 

 absorbed, and the absorption would still go on gradually. 



The collisions amongst the free meteorites became rarer and less 

 violent, and finally, when relative motion was nearly annulled, almost 

 ceased to occur. The residue of the meteoric swarm then consisted 

 of sparse flights of meteorites moving in streams. There is evidence 

 of the existence of such streams at the present day in the zodiacal 

 light, in falling stars, and in comets. But these are the dregs and 

 sawdust of the solar system, and merely give a memento of the myriads 

 which must have existed in early times, before the sun and planets 

 were formed. 



The subject of this lecture is a large one, and the limits of time 

 rendered it impossible to do more than speak of the more prominent 

 features of the problem. The value of the investigation of which 

 some account has been given, will appear very different to different 

 minds. To some it will stand condemned as altogether too specula- 

 tive ; others may think that it is better to risk error on the chance of 

 winning truth. It was, however, contended by the lecturer that the 

 line of thought flowed in the channel of truth, and that by its aid 

 many other interesting problems might perhaps be solved with suffi- 

 cient completeness to throw further light on the evolution of nebulas 

 and of planetary systems. 



[G. H. D.] 



