31. St. Gille, in 1771, made an experiment to test his ventriloquial talent before 3131. Leroy and Pouchy, commissioners of the Royal Academy of Sciences, and many other persons of the highest rank. The object of the experiment was to show that M. St. Gille's mimicry of sounds was so perfect as to produce illusion. For this purpose it was reported that a spirit's voice was at times heard in the environs of St. Germain, and that the commission was appointed to verify the fact and to discover the cause. All the company were in the secret except one lady, who, without suspecting it, was to be the subject of the illusion. They all dined in the country in the open air, and while they were at table a voice, as of a spiriteiuspended in the air, addressed the lady : now it seemed at the top of the trees ; then descending, it approached her—then receding, it plunged into the ground, whence it ceased not to make itself heard. Tho conversation was sustained upwards of two hours with such adroitness that the lady was fully convinced she had talked with a sylph ; and when the illusion was explained to her, she doubted if it were an illusion.
31. St. Gille, like Baron Mengen, made no secret of his art, but referred it all to mimicry, for which he had a strong propensity. The French Academy adopted the views contained in the statements of these two ventriloquists, namely, that the art consists in an accurate imitation of any given sound as it reaches the ear.
Adopting these views, physiologists have offered a variety of possible actions of the vocal organs to explain its production ; and some have even supposed a peculiarity of structure of the vocal organs as neces sary, but have wisely omitted to specify what. Many physiologists think that ventriloquism is vocally produced by speaking during inspiration of the breath. It is possible to speak during inspiration, and it may be occasionally adopted ; but close observation on many public ventriloquists, rind private friends who can ventriloquiso, con vinces the author of this article that the general current of utterance is, as in ordinary speech, on an expiration of the breath.
Adopting the views of the French Academy, some have thought that the vocal means of effecting the required imitation consist in a skilful management of the echoes of sound. Unfortunately, however, for this theory, an echo merely repeats what is already produced; and several ventriloquists, including the late Mr. Mathews, have produced the vocal illusion while walking in the streets.
Baron Mengen thus describes his mode of speaking when the voice was to seem to come from his doll :—" I press my tongue against the teeth, and thus circumscribe a cavity between my left cheek and teeth, in which the voice is produced by the air held in reserve in the pharynx (gosier). The sounds thus receive a hollow and muffled tone, which causes them to appear to come from a distance." Tho Baron says it is necessary to well manage the breath,and to respire as seldom as possible.
It was observed that M. St. Gino appeared fatigued after long exer tion, when the vocal illusion became less perfect. Those ventriloquists with whom the author of this article has conferred have acknowledged fatigue in the chest, which they have attributed to the extremely slow expira • tion of the breath. M. St. Gille, like most professional ven triloquists, was observed to cough very frequently.
Now, in order to arrive at exact and positive knowledge of the modi fications of voice termed ventriloquism, it is necessary to be familiar with the distinctions of vocal sound ; and to know how the organs act in producing those vocal modifications, it is necessary to know how the breath is vocalised in all its distinctions of pitch, loudness, and quality, by the ordinary actions of the vocal organs.
In ordinary language we speak of noise, of sound, and of musical sound; and Dr. Thomas Young adopts those terms in illustrating the mechanical causes of sounds :—" A quill striking against a piece of wood causes a noise ; but striking successively against the teeth of a wheel, or of a comb, a continued sound ; and if the teeth of the wheel are at equal distances, and the velocity of the rotation is constant, a musical sound." (` Lect. Nat. Phil.') The general terms pitch, loudness, quality, and duration embrace all the distinctions which the musician discovers in musical sounds, and which he employs in his art. The distinguishing feature of musical sound is its uniform pitch throughout its duration. And, acoustically musical sound is composed of an equal number of impulses or noises produced in equal times. [Acourrics ; VoicE.] The general terms pitch, loudness, quality, and duration also em brace all the distinctions heard in ordinary sounds. These sounds differ from the musical in the pitch constantly varying throughout their duration, as the human voice in speaking, and the voices of quad rupeds. Acoustically, such sounds are composed of an unequal number of impulses or noises produced in equal times. And from this circum stance pitch, in the strictly musical sense, is not a property of ordinary sound.
The general terms loudness and quality embrace all the distinctions heard in a noise, as in the collision of two inelastic sticks. The momentary collision of the clapper against a bell is a noise, but this mere noise is immediately followed by the ringing sound of the bell, which is a musical sound. Pitch and duration can scarcely be con sidered as belonging to common noise. Thus we have : I. Noise, whose audible distinctions are comprehended under the general terms loudness and quality.
IL Common sound, whose audible distinctions are comprehended under the general terms loudness, quality, duration, and ever-varying pitch.
III. Musical sound, whose audible distinctions are comprehended under the general terms loudness, quality, duration, and an uniform pitch.
Phonation, or the production of voice, is a result of actions taking place under two distinct classes of laws, namely : I. The ordinary mechanical laws of acoustics ; and 2. The physiological laws of mus cular movement. The adjustment of the vocal mechanism to be acted on by the current of air is made by actions under the latter laws; and phonation is the result of the reaction of the mechanism on the current of air, by mechanical movements under the former laws. in NAT. HIST. Dry.] The pitch of the voice essentially on the tension of the vocal ligaments ; the loudness on the extent of excursion of the vocal ligaments in their vibration ; the duration on the continuance of the vocalising causes ; and the quality on the organisation of the larynx, and also on the form and size of the vocal tube. Now the form and size of this tube can be altered in various ways, as by dilating or contracting the pharynx (PnaayNx, in