64 PHILOSOPHICAL SOCIETY OF WASHINGTON. 
stated, but in its final form energy seems to take leave of matter 
altogether, so far as our perceptions can followit, and disappear 
as a material phenomenon (though liable to reappear wherever 
matter is encountered whose particles are deficient in a like 
species of atomic motion with that which disappeared; which fact 
indicates that atomic mass is still a factor, with its inherent prop- 
erty of persistence and transference). The earth and all upon it 
is radiating heat energy away into space at the constant rate of 
500° F. of absolute temperature, more or less; the sun and the 
visible stars at the rate of many millions of degrees. Much energy 
also passes off in the luminous form. Of electrical and actinic 
energies we know less, and of some we doubtless know nothing. 
This amounts to a constant drain of the dynamical supply of 
energy. These final forms, the radiant energies, have a remark- 
able specific high cosmical velocity of their own, which is a func- 
tion of something not material, or at least not molar. It is sup- 
posable that, in addition to the dynamical source of motion from 
central forces, and the contraction of systems in dimension which 
supplies dissipation, there may be an inherent and primordial store 
of atomic motion. The high proper motion of some of the stars, 
beyond what can be accounted for on dynamical principles, and the 
inexhaustible and enormous supply of radiant energy from the 
visible stars, have afforded grounds for such a surmise, but these 
speculations do not belong to the domain of mechanics. 
And here we must bear in mind that the dynamical theory, in plac- 
ing these assumed agencies and modes of interaction in causal relation 
to phenomenal motion, by no means predicates or can predicate any- 
thing concerning absolute motion or its cause. The lack of this dis- 
tinction may have proved a stumbling block to some in comprehend- 
ing the idea of force. Were it not for the observed dissipation of 
energy no system could become contracted in dimensions a particle 
by the interactions of material forces, nor is there now any known 
way by which the material system can be expanded in dimensions 
except by the accession of motion from extra-mundane sources, 
which there is no scientific mode of ascertaining. The sum of mo- 
tions under the action of forces remains the same, and any change 
would imply creation or annihilation, which is not ascribable to a 
material agency. Primordial dimension remains as inscrutable 
a fact as ever, and primordial motion an unsolved problem. 
