From these observations it would appear, that Mr. Stewart had never witnessed those feats of the ventriloquist where his face is distinctly presented to the audience—­a case in which he must necessarily speak from within.  But independent of this fact, it is very obvious that there are many imitations, especially 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 performance, because the difference of the two directions was too great.  In like manner, when M. Alexandre introduced a boy from the street, and made him sing from his stomach the song of Malbrook, he placed his head as near as possible to the boy’s chest, under the pretence of listening, whereas the real object of it was to assimilate as much as possible the true and the fictitious direction of the sounds.  Had he placed the boy at the distance of six or eight feet, the real singer would have been soon detected.