262 T. C. ChamberUn — Jones's Criticism of 



rigid state and the viscous state. The essential consid- 

 erations in the former state are fixed attachments of the 

 constituents to one another at particular points by a force 

 which resists displacement, attended by a reacting elastic 

 force which tends to restore any displacement that may 

 take place. There is thus implied a resisting-yielding- 

 restorative combination. In the viscous state displace- 

 ment also requires force but displacement is not followed 

 by restorative action. The elastico-rigid state is not, as 

 its name clearly indicates, a state of ' i absolute ' ' rigidity, 

 but one of elastic yield. It thus becomes the basis for 

 certain typical modes of deformation and even of continu- 

 ous movement under differential stress, as in the case of 

 glacial motion and solid rock-flow as now interpreted by 

 the most critical students of these fields. 



In my serial paper on the self -compression of the earth 5 

 — which, as my only paper as yet built on the "ground- 

 work," should be taken as the chief index as to what "the 

 study of megadiastrophism is to be" — I have cited the 

 lucid illustration of this property offered by the electro- 

 magnetic poles developed by the revolution of electrons 

 about positive nuclei. Attachment by minute intense 

 poles of this type affords an ideal picture of fixation at 

 particular points conjoined with a restorative force. 

 This is probably the actual mode of formation of the 

 elastico-rigid state, but as it may be premature to insist 

 upon this, let it serve merely as a clear-cut index of the 

 type of view held. 



Now this is a very different picture from that which my 

 critic paints for me. As already stated he seems to me to 

 confound the effects of possible stresses not necessarily 

 connected in any way with the organization of the matter, 

 with the properties of the matter arising from the mode 

 of its organization. A spring balance is an illustration 

 of an elastico-rigid mechanism, but the properties of the 

 balance belong to one category while the varying strains 

 of commodities put on it to be weighed belong to a differ- 

 ent category. A modern steel bridge is a rigido-elastic 

 structure, but examining engineers are accustomed to 

 report its properties in fixed terms, not in variables 

 dependent on the stresses of a hand-car or a freight train 



5 Diastrophism and the Formative Processes : XV. The Self -Compression 

 of the Earth as a Problem of Energy, Jour. Geol., vol. 29, pp. 679-700, 1921. 



