y_. Let
us define by the term 'Energy,' this power which the rifle ball
possesses of overcoming obstacles, or of doing work."

Now, had Mr. Stewart been a better scholar, he would have felt,
even if he had not known, that the Greek word 'energy' could only
be applied to the living--and of living, with perfect propriety
only to the _mental_, action of animals, and that it could no more
be applied as a 'scientific garb,' to the flight of a rifle ball,
than to the fall of a dead body. And, if he had attained thus much,
even of the science of language, it is just possible that the small
forte and faculty of thought he himself possesses might have been
energized so far as to perceive that the force of all inertly
moving bodies, whether rifle stock, rifle ball, or rolling world,
is under precisely one and the same relation to their weights and
velocities; that the effect of their impact depends--not merely on
their pace, but their constitution; and on the relative forms and
stability of the substances they encounter, and that there is no
more quality of Energy, though much less quality of Art, in the
swiftly penetrating shot, or crushing ball, than in the
deliberately contemplative and administrative puncture by a gnat's
proboscis, or a seamstress' needle.

Mistakes of this kind, beginning with affectations of diction, do
not always invalidate general statements or conclusions,--for a bad
writer often equivocates out of a blunder as he equivocates into
one,--but I have been strict in pointing out the confusions of idea
admitted in scientific books between the movement of a swing, that
of a sounding violin chord, and that of an agitated liquid, because
these confusions have actually enabled Professor Tyndall to keep
the scientific world in darkness as to the real nature of glacier
motion for the last twenty years; and to induce a resultant
quantity of aberration in the scientific mind concerning glacial
erosion, of which another twenty years will scarcely undo the
damage.]

[Footnote 19: 'Force and pace.'--Among the nearer questions which
the careless terminology on which I have dwelt in the above note
has left unsettled, I believe the reader will be surprised, as much
as I am myself, to find that of the mode of impulse in a common
gust of wind! Whence is its strength communicated to it, and how
gathered in it? and what is the difference of manner in the impulse
between compressible gas and incompressible fluid? For insta