362 
BIGELOW. 
the amount of the disturbance of equilibrium, and conditions 
the rate at which the transfer of energy takes place, the ca¬ 
pacity measures the amount of energy that is transferred 
when the form of energy is changed. Hence under the law 
of conservation the amount of energy that one body loses 
the other gains, and therefore the sum of the capacities 
taken throughout the process is constant. The amount of heat 
one body loses the other gains in the new equilibrium; the 
amount of pressure one body loses the other gains, in order 
that equilibrium may be restored. If this equilibrium is dis¬ 
turbed by some change in the intensity, then the capacity 
measures the amount of the energy that can transfer under 
these circumstances, and the total energy transformed is the 
product of the intensity and the variation of the capacity. 
It may seem strange that the terms that we employ freely— 
force, mass, surface, volume, weight, electricity, and magnet¬ 
ism—are only forms of this capacity function, and that they 
are apprehended only during the instantaneous transfers of 
energy. It may cause surprise to perceive that the other 
set of terms we commonly talk about as entities, namely, 
temperature, velocity, potential and kinetic energy, height, 
pressure, tension, current, are perceived only during the 
transfer of energy; and it may be difficult to realize that 
we know nothing of heat, kinetic and potential energy, work, 
gravitation, friction, chemical, electric, and magnetic energy 
in their entities, but only in their processes of transfer. En¬ 
ergy is the great unknown entity and its existence is recog¬ 
nized only during its state of change. It may be surmised 
that we are here on the borderland of profound metaphysical 
speculations which we have no opportunity to enter upon 
at this time. 
For our immediate subject in hand, namely, the illustra¬ 
tion of the third canon of criticism, that every valid and new 
fact or law must be assigned to its proper rank in the hierarchy 
of science, we see at once that the foregoing analysis is of 
special significance. Here are more than a dozen examples 
from the processes of nature which can be classified under 
