DIASTROPHISM AND THE FORMATIVE PROCESSES 693 
disintegration has anything to do with relief of pressure, such as 
might be assigned to their rise from the interior, is now available. 
Any such possibility must be left to the revelations of the future. 
It is logically necessary, however, for one who believes in the indefi- 
nite cyclic persistence of the cosmos, to suppose that the present 
exothermic action is the reversal of an endothermic process that 
gave these elements the stores of energy they are now so persistently 
and systematically discharging. ‘The place and time and condi- 
tions of this storing action are altogether open questions. By 
interpretation, the energy now being given out springs from intense 
revolutional action, for revolutional motion seems to be the only 
probable way in which such prodigious energies can be stored in so 
unobtrusive a state and given out so regularly and systematically 
and in such concentrated forms. ‘The storing process must prob- 
ably have involved somewhat similar forms and intensities of action. 
One of the most common speculations as to the place and condi- 
tions of this storage process, locates it in some center of great 
stress where pressure and heat co-operated. This should perhaps 
be amended by recognizing that the more intense vibratory agencies 
of the X-ray end of the series were even more probable agencies, 
because their motions were more nearly commensurate with the 
minute and swift revolutions that are supposed to store the energy 
in question. The center of the earth is possibly a place of the right 
type, but it belongs to an inferior order compared with the centers 
of stars, unless solidity counts for something. In this case the 
center of the earth might have a preferred place, since our planet is 
among the largest of known solid bodies. An alternative specula- 
tion places the origin of the radioactive substances in the outlying 
regions of space. 
There is perhaps a suggestion of general atomic change in the 
remarkable phenomena of thermionic emission, contact potentials, 
and photoelectric action. These seem to imply that there is some 
kind of commensurability between the extremely intense oscilla- 
tions of the vibratory activities and the orbital periods of the 
electrons, so that effective interaction and perhaps interchange 
takes place between them. Commensurability is perhaps the 
property by which interchange is effected between the minutely 
