BiCKEKTON. — Evidence in favour of Impact. 471 



a series of discs of diameters diminishing with increase of 

 atomic weight. 



27. This fact taken in conjunction with the broadening of 

 the hnes into bands wiU enable us to calculate the distance 

 of such a body. 



28. The hydrogen will rob the heavy molecules of their 

 energy ; hence in any considerable graze the heavy metals 

 might not expand indefinitely. They would lose their velocity 

 by radiation and work done ; they would be attracted back 

 again and form a star. Some planetary nebulae have such 

 stars. 



29. In a partial impact the coalesced part will not have all 

 its motion converted into heat. On the two sides the 

 momentum will not be exactly balanced ; the body will conse- 

 quently tend to spin. It is generic of partial impact that it 

 tends to cause rotation in all the bodies produced, and the 

 rotation is all in the same direction. 



30. It is a peculiarity of oxygen that it tends to render its 

 compound with metals less volatile than the metals them- 

 selves. Almost all oxides are less volatile than the metals 

 forming them. Consequently when metal and oxygen come to- 

 gether they produce molecules that tend to coalescence. Thus 

 nuclei form in a nebula and it becomes dusty. If the nebula 

 be rotating this dust tends to move in orbits, constantly 

 picking up other dust and molecules. Thus a rotating metallic 

 nebula tends to aggregate, not necessarily into a single body, 

 but into a mass of bodies orbitally connected. If the mass 

 be large it will become a star-cluster ; if small, a meteoric 

 swarm. 



31. In star-clusters impacts should be frequent. These 

 groups should be photographically watched to notice sudden 

 increase of intensity, and then the pair of impacting stars 

 should be watched for nebula and for variability. 



32. Meteoric swarms when near the sun would be dis- 

 torted, and the constituents would impact with extraordinary 

 frequency ; they would become very brilliant, and show as 

 comets. There would be tremendous development of elec- 

 tricity. 



33. It is certain that the matter of the tail of a comet does 

 not belong to the comet. It is like the motes in air illuminated 

 by a search-light. The phenomenon of the tail is almost 

 certainly electrical. 



34. Such a swarm when near the sun would have its near 

 part drawn in advance of, and its distant part left behind, the 

 general swarm. Its weak attractive power would cause it to 

 divide into a train. 



35. The two stars that gi-azed would have a part cut out 

 of each. This would expose the hot interior. A portion of 



