170 ON THE ORIGIN OF THE PLANETARY SYSTEM. 



which move in regular elliptical orbits, cutting the 

 earth's orbit in definite places, and therefore always 

 oc$ur on particular days of the year. Thus the 10th 

 of August of each year is remarkable, and every thirty- 

 three years the splendid fireworks of the 12th to the 

 14th of November repeats itself for a few years. It is 

 remarkable that certain comets accompany the paths 

 of these swarms, and give rise to the supposition that 

 the comets gradually split up into meteoric swarms. 



This is an important process. What the earth 

 does is done by the other planets, and in a far higher 

 degree by the sun, towards which all the smaller 

 bodies of our system must fall ; those, therefore, that 

 are more subject to the influence of the resisting 

 medium, and which must fall the more rapidly, the 

 smaller they are. The earth and the planets have for 

 millions of years been sweeping together the loose 

 masses in space, and they hold fast what they have once 

 attracted. But it follows from this that the earth and 

 the planets were once smaller than they are now, and 

 that more mass was diffused in space; and if we 

 follow out this consideration it takes us back to a 

 state of things in which, perhaps, all the mass now 

 accumulated in the sun and in the planets, wandered 

 loosely diffused in space. If we consider, further, that 

 the small masses of meteorites as they now fall, have 

 perhaps been formed by the gradual aggregation of 



