THE SUN 277 



critical point in gases; signifying that, given a certain 

 temperature (varying, of course, with the substance), no 

 application of pressure, however great, that may be 

 brought to bear will avail to reduce the gas to the form of 

 a solid or liquid. Now, if this generalization is valid, 

 then it necessarily follows that the heart of the sun is 

 gaseous, since there the temperatures prevailing are 

 demonstrdbly above the critical point of every known 

 chemical element. But though the interior of the sun is 

 gaseous, it does not follow that the whole globe is. On 

 the contrary, when we consider his high internal tempera- 

 tures, and his high density as compared with what he 

 ought to possess were he in a solely gaseous state, we 

 soon come to realize that the sun can be nothing else than 

 an enormous inflated solid or liquid shelL Not only does 

 this conclusion obviate the postulation of a chimerical 

 fourth state of matter, and account for the persistence of 

 sun-spot identity and the enigmatic low density of the 

 sun, stars and planets, but, as we shall presently see, it 

 also supplies the clue to practically every mystery of 

 star-life and star-behavior from the moment the star 

 crystallizes out of the nebular dust until it dissolves into 

 nebular dust again. 



After all, what is this doctrine of the critical point 

 except a general recognition of the explosibility of all 

 substances by percussion, or crushing? Dynamite may 

 be detonated by raising its temperature, by a sudden 

 blow, by friction, or by strong pressure. So may any and 

 every other substance. "Give me," said Archimedes, 

 "a lever long enough and I will move the earth ", and so 

 I say, give me a press powerful enough and I will deton- 

 ate any known substance, whatever be its temperature, 

 from gunpowder to granite. Apropos of this statement 

 let me quote from the pen of that world-wide authority, 

 J. W. Gregory, Professor of Geology at the University 

 of Glasgow (Geology of To-day, p. 157) : 



The ordinary rocks on the earth's surface are crushed into 

 powder when subject to a weight of somewhere between two and 

 thirty tons to the square inch. Hence if a column of ordinary 

 rocks were built from 3 to 5 miles high, the base would be crushed 



