278 FROM NEBULA TO NEBULA 



by the weight of the upper part. Rocks are often found in such 

 a condition of strain that they fly to pieces when exposed on one 

 side in a deep mine. In some mining fields the rocks cut through 

 in driving a mine tunnel suddenly explode owing to the strain of 

 the overlying weight, just as a spring may snap when overloaded. 

 Fragments are thrown from the rock face in 'rock blasts', and 

 have caused many fatal accidents. 



This detonation of rocks (and other materials as 

 well, including metals) is no more than should be philo- 

 sophically expected. That the three states of matter, 

 solid, liquid and gaseous, must follow each other m a 

 cycle at peril of destroying Nature's very life seems all 

 but axiomatic. Were the fact otherwise, matter, once 

 caught in the trap of gravitation and held down by super- 

 incumbent layers, would become perpetually staled and 

 nullified ; which is repugnant to sound reason. We know 

 from experience that the heavier the pressure brought to 

 bear, the less space does the compressed substance oc- 

 cupy. Were this rule to apply indefinitely, it would 

 mean nothing less than the final extinction of matter by 

 shrinkage into no space at all. Where does this trend 

 cease and the recovery begin ? How does Nature restore 

 the balance? What logical thing remains for the tor- 

 tured molecules to do, but to rebel and bombard the walls 

 of their prison till these yield as to an acid and vouchsafe 

 escape? 



Heretofore it has always been assumed as quite a 

 matter of course that matter thus gravitationally en- 

 trapped in the interior of cosmic bodies is forever 

 rendered subservient to the ever accumulating material 

 overhead. It seems never to have suggested itself to the 

 minds of the physicists that the burdened materials could 

 ever find a way of release. Yet what deduction could be 

 more simple than that, given a sufficient body of rock 

 ripe for exploding, it would not need to await emancipa- 

 tion from the tardy hand of man, but, seeking the path of 

 least resistance, would tear its own way, here or there, 

 through to the surface? It is in this essentially ex- 

 plosible nature of matter, under varying pressures, that 



