r inertia is the measure of their rates of
exchanging energy.

THE ETHER IS CONDITIONALLY POSSESSED OF INERTIA.

A moving mass of matter is brought to rest by friction, because it
imparts its motion at some rate to the body it is in contact with.
Generally the energy is transformed into heat, but sometimes it appears
as electrification. Friction is only possible because one or both of the
bodies possess inertia. That a body may move in the ether for an
indefinite time without losing its velocity has been stated as a reason
for believing the ether to be frictionless. If it be frictionless, then
it is without inertia, else the energy of the earth and of a ray of
light would be frittered away. A ray of light can only be transformed
when it falls upon molecules which may be heated by it. As the ether
cannot be heated and cannot transform translational energy, it is
without inertia for _such_ a form of motion and its embodied energy.

It is not thus with other forms of energy than the translational. Atomic
and molecular vibrations are so related to the ether that they are
transformed into waves, which are conducted away at a definite rate.
This shows that such property of inertia as is possessed by the ether is
selective and not like that of matter, which is equally "inertiative"
under all conditions. Similarly with electric and magnetic phenomena, it
is capable of transforming the energy which may reside as stress in the
ether, and other bodies moving in the space so affected meet with
frictional resistance, for they become heated if the motion be
maintained. On the other hand, there is no evidence that the body which
produced the electric or magnetic stress suffers any degree of friction
on moving in precisely the same space. A bar magnet rotating on its
longitudinal axis does not disturb its own field, but a piece of iron
revolving near the magnet will not only become heated, but will heat the
stationary magnet. Much experimental work has been done to discover, if
possible, the relation of a magnet to its ether field. As the latter is
not disturbed by the rotation of the magnet, it has been concluded that
the field does not rotate; but as every molecule in the magnet has its
own field independent of all the rest, it is mechanically probable that
each such field does vary in the rotation, but among the thousands of
millions of such fields the average strength of the field does not vary
within measurable limits. Another