BiCKERTON. — Evidence in favour of Impact. 473 



motion were small, and the graze on an average more than a 

 tenth, then the two stars would become orbitally connected. 



46. Such a pah form a permanent double star. Proctor 

 and other astronomers are of opinion that impacting stars that 

 become orbitally connected could not make double stars, as 

 they would impact again. They overlook the fact that the 

 nebula that retarded their escape will have dissipated before 

 they return, hence the eccentricity will lessen greatly, and, as 

 a rule, instead of impacting again, they will be scores of mil- 

 lions of miles away at perihelion. 



47. Double stars should be more often variable than single 

 stars. Struve has proved that they are hundreds of thousands 

 of times more so than ordinary stars. They should be more 

 frequently coloured. This is also most strikingly the case. 



48. They should be associated with nebulae. Herschel says 

 the association of nebula3 and double stars is truly remarkable. 



49. They should be highly eccentric. This is also well 

 known to be the case. 



50. A large number of agencies tend to render the orbit 

 less eccentric. These are fully described in my papers of 

 1880. 



51. If stars come into partial impact the tendency to form 

 definite nebulae other than planetary or cometic seems to be 

 entirely destroyed by the outrush of the high-velocity gas. 

 This is not the case with the impact of nebulae. 



52. Impact may take place between nebulee, between 

 star -clusters, between meteoric swarms, and, of course, be- 

 tween any two similar or dissimilar celestial bodies. The 

 graze may be large or small; the original bodies may htive had 

 a little or great proper motion. Of course, all these peculiari- 

 ties will tend to vary the results. 



53. If two nebulae come into a slight grazing impact a 

 double nebula will result. This will show a spindle at the 

 centre. As they are parting company they may have tem- 

 porarily a dumb-bell appearance, but the two sides of the 

 coalesced nebula are moving in opposite directions. A spiral 

 begins to form at the centre, the ends travel on in space, the 

 spiral increases, and ultimately a double spiral results. 



54. One or both of the original nebulte may be entangled 

 in the spiral. 



55. If the impact be considerable the two nebulae do not 

 escape each other, and an annular nebula results. It has 

 gauzelike masses of nebulge at the poles of the rings, produced 

 by the outrush during the impact. 



56. If two universes such as the Magellanic Clouds 

 impact, an annular universe will result. The poles will be 

 covered with nebulous matter, due to the outrush of gas 

 during the millions of years of the impact. 



