260 T. C. Cliamberlin — Jones's Criticism of 



grown earth is 194 diameters of the earth, The sphere 

 of control of the self-controlled portion of the erupted 

 mass obviously could not have been so large as this. 

 Taking the ultra-maximal sphere of control as a working 

 basis to give a margin of safety, the volume of the erupted 

 mass due to radial dispersion simply — 430 times the 

 earth's diameter — compared with the volume of the pres- 

 ent sphere of control — 194 times the earth's diameter — 

 shows that less than one-tenth of the erupted mass lay 

 within even the ultra-maximal sphere of control. To this 

 dispersion should be added the dispersive effects of gase- 

 ous expansion and of eruptive scattering. Over against 

 these additional dispersive factors there is only the allow- 

 ance to be made for the inward curvature of the projected 

 constituents due to their mutual gravity during their 

 swift short flight under the projectile forces. 



I think that every competent reader will see that, with- 

 out laying stress on any factor that depends upon personal 

 judgment, the collecting nucleus would only have included 

 a minor fraction of the projected matter. The rest must 

 have gone into independent orbits from which collection 

 by orbital dynamics would have been very slow and the 

 development of a holpmolten state of the earth quite out 

 of the question. 



It thus appears clear to the point of practical demon- 

 stration that a molten state would not arise normally 

 under the terms of the planetesimal hypothesis, and that 

 the attempt to graft such a state on the hypothesis merely 

 gives rise to an incompatibility, not to an issue. 



Contrasted views of rigidity. — It has thus taken much 

 space to clarify the issues projected in the Introduction 

 before any semblance of real review began, but another 

 such projection immediately follows relative to the mean- 

 ing of rigidity, as follows : 



"The term 'rigidity' lias been generally loosely interpreted. 

 Rigidity is dependent not only on the stress applied but upon 

 the time the stress is applied. A material may be rigid for one 



set of stress conditions and non-rigid for another Rigidity, 



then, is merely a relative term. ' ' 



There is just enough of truth and of misconception in 

 this to make it very misleading. Two things are easily 

 confounded: (1) the property of rigidity whose values 



