PHYSICAL EVOLUTION 3 



The close connection between the orbits of comets 

 and those of meteoritic streams has led to the 

 universally admitted conclusion that comets are 

 neither more nor less than swarms of meteorites. 

 Again, the resemblance between the spectra of 

 comets and those of nebula3 suggests that these also 

 are swarms, or aggregations, of meteorites. And we 

 naturally infer that the stars with similar bright- 

 line spectra must be collections of meteorites. From 

 bright-line stars we pass to those whose meteoritic 

 origin is no longer to be recognised, all having 

 blended together. Further it is claimed that by 

 supposing variable and temporary stars to be due to 

 the meeting and entanglement of two meteoritic 

 swarms we get a better explanation of the observed 

 phenomena than any other hypothesis can give. 



Evolution of the Universe. This meteoritic 

 hypothesis supposes that the present material 

 Universe was at one time in a state of 

 " cosmic dust," spread irregularly through space, 

 and moving slowly in many directions. It is the 

 original irregular distribution of the cosmic dust and 

 its irregular movements which are the source of all 

 the energy in the Universe. We have specimens 

 of this cosmic dust in the chrondroi , or spherules , of 

 which many of the stony meteorites are built up. 

 They are small round bodies of crystallised minerals, 

 varying from microscopic dimensions to the size of 

 a marble. Of course these chondroi are not the 

 first form in which matter existed. They are 

 evidently due to chemical reactions, and we could 

 frame several different hypotheses as to their origin 



