The study of the artificial limbs which owe their perfection to his
skill and long-continued labor has led us a little beyond its first
object, and finds its natural prelude in some remarks on the natural
limbs and their movements. Accident directed our attention, while
engaged with this subject, to the efforts of another ingenious American
to render the use of our lower extremities easier by shaping their
artificial coverings more in accordance with their true form than is
done by the empirical cordwainer, and thus _Dr. Plumer_ must submit to
the coupling of some mention of his praiseworthy efforts in the same
pages with the striking achievements of his more aspiring compatriot.

We should not tell the whole truth, if we did not own that we have for
a long time been lying in wait for a chance to say something about the
mechanism of walking, because we thought we could add something to what
is known about it from a new source, accessible only within the last
few years, and never, so far as we know, employed for its elucidation,
namely, _the instantaneous photograph_.

* * * * *

The two accomplishments common to all mankind are walking and talking.
Simple as they seem, they are yet acquired with vast labor, and very
rarely understood in any clear way by those who practise them with
perfect ease and unconscious skill.

Talking seems the hardest to comprehend. Yet it has been clearly
explained and successfully imitated by artificial contrivances. We
know that the moist membranous edges of a narrow crevice (the glottis)
vibrate as the reed of a clarionet vibrates, and thus produce the human
_bleat_. We narrow or widen or check or stop the flow of this sound by