ly those of the cries of particular
animals, and of sounds of a high pitch, which cannot be performed _pleno
ore_, by the ordinary modes of utterance, but which require for their
production that very faculty, of which Mr. Stewart doubts the existence.
Such sounds are necessarily produced by the throat, without requiring the
use of the mouth and lips; and the deception actually depends on the
difference between such sounds, and those which are generated by the
ordinary modes of utterance.

The _art_ of ventriloquism, therefore, consists in the power of
imitating all kinds of sound, not only in their ordinary character, but as
modified by distance, obstructions, and other causes; and also in the
power of executing those imitations by muscular exertions which cannot be
seen by the spectators. But these powers, to whatever degree of perfection
they may be possessed, would be of no avail if it were not for the
incapacity of the ear to distinguish the directions of sounds--an
incapacity not arising from any defect in the organ itself, but from the
very nature of sound. If sound were propagated in straight lines, like
light, and if the ear appreciated the direction of the one, as the eye
does that of the other, the ventriloquist would exercise in vain all the
powers of imitation and of internal utterance. Even in the present
constitution of the ear, his art has its limits, beyond which he must be
cautious of pushing it, unless he calls to his aid another principle,
which, we believe, has not yet been tried. In order to explain this, we
shall analyze some of the most common feats of ventriloquism. When M.
Fitzjames imitated the watchman crying the hour in the street, and
approaching nearer and nearer the house, till he came opposite the window,
he threw up the window-sash, and asked the hour, which was immediately
answered in the same tone, but clearer and louder; and upon shutting the
window, the watchman's voice became less audible, and all at once very
faint, when the ventriloquist called out, in his own voice, that he had
turned the corner. Now, as the artist was stationed at the window, and as
the sound from a real watchman must necessarily have entered by the
window, the difference between the two directions was considerably less
than that which the ear is unable to appreciate. Had the ventriloquist
stood at one window, and tried to make the sound of a watchman's voice
enter _another_ window, he would have failed in his pe