f the loss of
energy in some other body, or in some other form.

All changes of energy, therefore, are simply changes due to the
difference in form in which the energy is manifested. At one time it
will be manifested in the form of light, then of heat, then in
mechanical motion, and so on. Joule gave us some good illustrations of
this principle of the conservation of energy. He showed us how
electricity could be changed into heat, and the heat into work. When
light, which is a form of energy, is absorbed by any opaque body, it is
found that the body which has absorbed it has become hotter. The energy
of light has not been destroyed, but as its energy cannot pass through
the opaque body, it has been employed in agitating the particles and
atoms of that body, which becomes hotter in consequence.

Thus from the principle of the conservation of energy, which is in
operation not only in our planetary world, but throughout the whole of
the solar and stellar space, and indeed throughout the whole universe,
we arrive at the conclusion that the total quantity of energy throughout
the universe is unchangeable. In the evolution and development of
worlds, and in the destruction of those worlds after long periods of
time, throughout all the varied manifestations of heat, light,
electricity, and magnetism, associated with the development and
destruction of each globe, the sum-total of the energy of the universe
remains the same. Meteors may rush into the atmosphere of planets, and
be dissolved into Aether through the friction, comets may be dissolved
into their component gases as they near the sun, water may be changed
into vapour by the heat of the summer sun, vegetation may be produced
from apparently dead matter, and then that vegetation may itself decay
and return to the dust by which it had been built up, but throughout all
these processes of birth and death, of evolution and devolution, the
sum-total of active living energy which is associated with all the
phenomena, remains unalterable and unchangeable. Such is the teaching of
the great principle of the Conservation of Energy as enunciated by Mayer
and Helmholtz.

ART. 53. _Transformation of Energy._--One of the chief characteristics
of energy is, that we can transform it, and it is chiefly of use to us
because of its capability to be transformed, but in all its
transformations, the total quantity of energy remains the same. The
transformation of energy renders it necessa