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
the lips, the tongue, the teeth, and thus _articulate_, or break into
joints, the even current of sound. The sound varies with the degree and
kind of interruption, as the "babble" of the brook with the shape and
size of its impediments,--pebbles, or rocks, or dams. To whisper is to
articulate without _bleating_, or vocalizing; to _coo_ as babies do is
to bleat or vocalize without articulating. Machines are easily made that
bleat not unlike human beings. A bit of India-rubber tube tied round a
piece of glass tube is one of the simplest voice-uttering contrivances.
To make a machine that _articulates_ is not so easy; but we remember
Maelzel's wooden children, which said, "Pa-pa" and "Ma-ma"; and more
elaborate and successful speaking machines have, we believe, been since
constructed.

But no man has been able to make a figure that can _walk_. Of all the
automata imitating men or animals moving, there is not one in which the
legs are the true sources of motion. So said the Webers[A] more than
twenty years ago, and it is as true now as then. These authors, after a
profound experimental and mathematical investigation of the mechanism
of animal locomotion, recognize the fact that our knowledge is not yet
advanced enough to hope to succeed in making real walking machines. But
they conceive that the time may come hereafter when colossal figures
will be constructed whose giant strides will not be arrested by the
obstacle