236 Canadian Record of Science. 



out from the sun would travel under the law of gravitation 

 nearly in a straight line outward and back again into the 

 sun. If in its course it enters the earth's atmosphere, its 

 relative motion, that which we see, should be in a line par- 

 allel to the ecliptic, except as slightly modified by the 

 earth's attraction. A large number of these meteors, that 

 is most, if not all, well observed fireballs, have certainly not 

 travelled in such paths. These did not come from the sun. 

 It has been a favorite hypothesis that the meteorites 

 came from some planet broken in pieces by an internal 

 catastrophe. There is much which mineralogists can say 

 in favor of such a view. The studies of M. Stanislas 

 Meunier and others, into the structure of meteorites have 

 brought out many facts which make their hypothesis plau- 

 sible. It requires, however, that the stone-meteor be not 

 regarded as of the same nature as the star-shower meteor, 

 for no one now seriously claims that the comets are frag- 

 ments of a broken planet. The hypothesis of the existence 

 of such a planet is itself arbitrary ; and it is not easy to 

 understand how any mass that has become collected by the 

 action of gravity and of other known forces should by inter- 

 nal forces be broken in pieces, and these pieces rent asun- 

 der. The disruption of such a planet by internal forces 

 after it has by cooling largely lost its original energy, 

 would be specially difficult to explain. 



We cannot then look to the moon, nor to the earth, nor 

 to the sun, nor to any of the large planets, nor to a broken 

 planet as the first home of the meteoroides, without seeing 

 serious if not insuperable objections. But since some of the 

 meteoroides were in time past certainly connected with 

 comets, and since we can draw no line separating shooting 

 stars from stone-meteors, it is most natural to assume that 

 all of them are of a cometary origin. 



And if the cometary origin of meteorites is inadmissible, 

 the objections must mainly come from the nature and 

 structure of meteoric stones and iron. 



What that structure is, and to some extent what condi- 

 tions must have existed at the time and place of its first 

 formation and during its subsequent transformations, miner- 



