FORMATION OF METEORITES 39 ^ 



in the central portion of the stellar system, in which the sun 

 seems to be placed at present, the general attractions are prob- 

 ably nearly balanced. Two stars, therefore, whose speeds are 

 sub-equal and whose paths gently converge, ma}^ be controlled 

 almost freely by their mutual attractions after they come within 

 the spheres of each other's dominant influence. Such stars under 

 mutual control would describe paths relative to each other 

 similar to those assumed in the discussion. Their closeness of 

 approach at periastron would be determined by the relative 

 differences (not the total amounts) of their speeds and momenta." 

 The principle of sub-parallel movements applies here and gives 

 results quite at variance with those that obtain in cases of opposed 

 movements, where the relative sums of the velocities and 

 momenta are to be considered. The movements of the long- 

 orbit comets seem to be concrete expressions of this principle, 

 as their perihelia are largely clustered on the front side of the 

 Sun, /. e., the side toward which it is moving, and they make 

 close approaches to it. Such star clusters as the Pleiades, the 

 members of which seem to have proper movements nearly the 

 same in amount and direction, are doubtless also expressions of 

 the principle of sub-parallelism, and in their remarkable neb- 

 ulosity they may at the same time illustrate the doctrine of dis- 

 turbed secondaries leading on to dispersive action, a part of the 

 product of which remains associated with the stars themselves, 

 while a part is more or less widely scattered, as the terms of the 

 doctrine require. 



If our stellar system has a definite boundary and is a flat- 

 tened spheroidal cluster or a discoid, and if the ideal paths of the 

 stars are elongate orbits stretching from border to border across 

 the heart of the cluster (except as diverted by close approaches) , 

 then the orbital speeds and momenta should be lowest on the 

 outer surface, and the paths should there be most frequently 

 sub-parallel, and hence the conditions for the close approach of 

 two suns through their reciprocal attraction be there most favor- 

 able. Now, visible nebulae are most frequent in the regions 

 polar to the Milky Way, and they may be regarded as lying on 



