904 J. BARRELL MEASUREMENTS OF GEOLOGIC TIME 



sorbed as au added store of energy. The coefficient of expansion is also 

 small and indicates that the energy of the absorbed heat only slightly ex- 

 pands the sphere of the atonies influence. The internal fixed energy of 

 the atom is therefore enormous as compared with that which can be added 

 or taken away by processes under human control. 



In some manner the elements must have had their evolution, and ac- 

 cording to the law of the conservation of energy that which the stars are 

 now liberating must first have been absorbed. The apparent running 

 down of the visible universe must be but one phase of a recurrent cosmic 

 cycle philosophically necessary in infinite time, or else the running down 

 would have been completed in previous eternity. The nature of this cyclic 

 process is still far beyond the bounds of scientific investigation. It was 

 thought that in gravitational infall an adequate explanation had been 

 found for one phase of the cycle, that of the liberation of the radiant 

 energy of the stars ; but the quantities dissipated by the sun through the 

 vast length of geologic time indicate that the contraction of the solar 

 mass can not be more than a minor factor in the conversion of its energy. 



The scheme of the universe is more profound and the unknown is a 

 little nearer than it was recently thought to be. But such has been the 

 progress of knowledge since man, in the days before the advent of science, 

 naively regarded the earth, his home, as the center of the universe and 

 the heavenly bodies as lights in a near-by firmament, created a few thou- 

 sand years previously especially for his benefit. 



