AND ITS INHABITANTS 47 



berlin and Moulton, had a long antecedent history before it 

 gave birth to its planetary system. Therefore before there 

 was an earth, the sun had been condensing and moving undis- 

 turbed in space for countless ages, until it came within the 

 influence of another and a greater star. The gravitative 

 influence of this mighty passing intruder acted catastrophically 

 upon the sun and caused its partial disruption. As a conse- 

 quence, from opposite sides of the sun there streamed rapidly 

 outward materials of its own mass that soon arranged them- 

 selves into a two-armed luminous spiral nebula. The mass 

 which was so extruded, and which did not fall back again into 

 the sun, was less than i per cent of the sun's mass, and yet it 

 gave rise to the planetary system which encircles the parent 

 body. From this we also the more readily appreciate the 

 great size of the parent sun, whose volume is 1,300,000 times 

 greater than that of the earth. 



Growing earth during the Formative era. In the solar 

 nebula there existed eight knots of more or less loosely aggre- 

 gated denser and hotter matter, the nuclei of the future minor 

 and major planets and their satellites, and these in the course 

 of time attracted to themselves most of the surrounding nebu- 

 lous material, usually spoken of as the planetesimals. The 

 earth-knot, it is estimated, may have had an original diameter 

 of about 5,500 miles, and the moon-knot perhaps half its 

 present diameter of 2,162 miles. In the course of cosmic time, 

 the earth and moon, revolving as companions about the sun, 

 gathered into themselves the planetesimals that lay within 

 their spheres of influence. 



The speaker holds to the postulate of Barrell that the plan- 

 etesimals conceived by Chamberlin to have been of the size of 

 sand and dust were probably for the most part much larger 

 and more like the planetoids in dimensions. From time to 

 time, as one or more of the planetoid-like bodies, singly or in 

 combination, plunged in upon the earth with velocities up to 



