292 FROM NEBULA TO NEBULA 



this advantage, however, wisps of the most tenuous mat- 

 ter will always remain uncaptured and continue to litter 

 the zone of the ecliptic indefinitely. These wisps, being 

 illuminated by the sun outside the boundaries of the 

 earth's shadow, are responsible for the phenomena known 

 as the Zodiacal Light and Gegenschein. Incidentally, be 

 it added, this residuary nebular matter is forever seeking 

 to preserve its equilibrium, in pursuit of which it hovers 

 near the plane of the ecliptic, as part of the main vortex ; 

 and where it pervades the earth-moon subordinate vortex,, 

 it affects the plane of the lunar orbit. 



When I say that the planets devour this nebular mat- 

 ter, I do not mean to exclude from the cannibalistic feast 

 the asteroids, satellites, or even the meteors, that help to 

 make up our system. All of these share impartially, ac- 

 cording to their respective gravitative voracities. Fur- 

 thermore, they stand the same risk of being struck by 

 the flying missiles. This suggests the question as to 

 what should be the direct effect upon terrestrial life were 

 such a catastrophe as I have described to take place to- 

 day. 



Granting that the earth is the built-up product of 

 10,000 such contributions from the solar mass, and that 

 the same thing is true of all the rest of the planets and 

 satellites, then, since all these together equal 1-750 of the 

 sun, it follows that the latter loses on each such occasion 

 only 1-7,500,000 of his corpus, or, say, 1-20 of an earth. 

 Since the earth's disc, as previously computed, intercepts 

 only 1-2,000,000,000 of the sun's light, of course it would 

 likewise intercept only the 1-2,000,000,000 of 1-20 of six 

 sextillions of tons of weight, or 150,000,000,000 of tons- 

 equal to 750 tons to the square mile, or, say, 1.25 tons to 

 the acre, taking in the entire area of the earth's surface. 

 Of course this solar hail would not be evenly distributed, 

 unequal fragments being promiscuously scattered here 

 and there, while the night side of the planet and other 

 sheltered places might escape scot free. The real incre- 

 ment to the planet's growth would not be acquired by 

 this direct bombardment, but by the subsequent slow 

 gleanings from the nebula. 



