478 



T. C. CHAMBERLIN 



the larger bodies of the soHd order. They thus serve to put to 

 severe test our notions as to the formation of such bodies. It 

 will not be surprising if we find that these small bodies lie on the 

 precarious border that separates successful aggregation from 

 dissipation into planetesimals. 



TABLE II 



Dynamical Properties of Ten Representative Bodies of the 

 Terrestrial and Smaller Classes 



The selections are adapted to the earth as unit and the spheres of control 

 are based on the earth's distance from the sun. An ideal body -h the mass of 

 the earth is introduced between Mars and the moon to better grade the series, 

 and for a like reason an ideal body i ,000 miles in diameter is introduced below 

 the moon. The four ideal bodies, 500, 100, 50, and 10 miles in diameter, 

 respectively, are selected to cover the range of the planetoids and smaller 

 satellites. The largest of planetoids thus far measured satisfactorily is 485 

 miles in diameter (Barnard). Two hypothetical densities are assigned to 

 each of these, the one to represent bodies supposed to be composed largely 

 of stony matter, the other to represent those that may have a notable content 



