12 T. C. CHAM BERLIN 



While meteorites in the main seem to belong to the solar system, 

 they appear to be samples from many sources, for they are extremely 

 numerous and come to the earth from various directions and at 

 very different velocities. It is therefore thought that they fairly 

 represent the nature of any kind of scattered interplanetary matter 

 of the soHd t5q3e that might once have been available for the 

 formation of small planets and satellites. This view does not rest 

 so much upon their present status as upon the dynamics of the case, 

 for the self-aggregation of small masses implies feeble graivitative 

 control, and under the conditions of such feeble control only the 

 heavier, sluggish molecules can be gathered and held. For this 

 reason meteoritic material is taken to represent the densest type 

 of scattered solid particles and small masses, whether planetesimal, 

 satellitesimal, meteoritic, or otherwise, available now or in the past, 

 for the growth of satellites and planets. This of course does not 

 exclude the availability of lighter material, even gaseous material, 

 to planets massive enough to hold such material, nor does it exclude 

 occluded or combined gases from even the smallest bodies. 



In building up these parity-earths, the series starts with the 

 moon, the lowest in mean density, rises thence through Mars and 

 the representative meteorite, to Venus, next to the earth in mean 

 density, and ends with our planet. This arrangement should 

 suggest at once that as the last two are the most massive bodies 

 and hence have the greatest power of holding light molecules, they 

 probably have the largest proportions of inherently light matter 

 in their composition. 



THE NUMERICAL RESULTS 



The leading numerical results of the computations are gathered 

 into Table II. 



Let us hasten to admonish ourselves that these results are as yet 

 uncriticized. Before the inquiry may properly rest these results 

 must be scrutinized in the light of the dynamical conditions under 

 which the four bodies were formed, for these conditions were such 

 as to determine the inherent heaviness or the inherent lightness of 

 the matter that formed them. This critical phase of the study will 

 take us rather far afield and must therefore be deferred to a later 

 article. I feel warranted, however, in saying that this further study 

 will indicate, as does the hint given above, that the more massive 



