Bickekton. — On Cosmic Impact. 549 



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

 compounds with metals less volatile than are the metals them- 

 selves. Almost all oxides are less volatile than the metals 

 forming them. Consequently, when metallic atoms and 

 oxygen come together, they produce molecules that tend to 

 coalesce. Thus nuclei form in a nebula and it becomes dusty. 

 If the nebula be rotating this dust tends to move in orbits, 

 and it would be constantly picking up other dust and mole- 

 cules. Thus a rotating metallic nebula, in which molecular 

 selective escape has dissipated the light molecules, tends to 

 aggregate, not necessarily into a single body, but oftener into 

 a number 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 observed to notice any 

 sudden increase of intensity. Then the pair of impacting 

 stars should be watched for nebulas and for variability. 



Comets. 



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

 torted, and the constituent fragments would impact with 

 extraordinary frequency. They would therefore become very 

 brilliant, and show as comets. The friction would produce an 

 enormous development of electricity. 



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

 not belong to the comet itself. It is the dust of space lit up 

 in some way like motes in air illuminated by a search-light. 

 The phenomenon of the tail is almost certainly electrical. In 

 a paper " On a New Eelation between Heat and Electricity" 

 I have discussed agencies that may explain the phenomenon. 



34. Such a swarm, when close to the sun, would have its 

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

 rear of, the general swarm. Its weak attractive power would 

 cause it to separate into a train. 



The above are some of the phenomena that may ensue in 

 the coalesced mass. 



Vakiable Staks. 



35. The two stars that grazed would have a part cut out 

 of each : this would expose the probably hot interior. Each 

 star would entangle a portion of the other. This would in- 

 crease the temperature and luminosity of the cut part of each. 



36. The stars after collision would recover their sphericity 

 chiefly by the molten interior welling up. This by momentum 

 would overfill the space, and there would be a rhythmic tidal 

 action, the molten lake overfilling and then sinking. 



37. The retardation of the sheared stars by the entangled 

 material would cause them to spin. This would act chiefly 



