Part 11

If a noise be made in a narrow passage, or apartment of regular form, the echoes will be repeated at equal very small intervals, and will always impress the ear with a musical note. This is, doubtless, one of the means which blind persons have of judging of the size and shape of any room they happen to be in.

VENTRILOQUISM.

The main secret of this surprising art simply consists in first making a strong and deep inspiration, by which a considerable quantity of air is introduced into the lungs, to be afterwards acted upon by the flexible powers of the larynx, or cavity situated behind the tongue, and the trachea, or windpipe: thus prepared, the expiration should be slow and gradual. Any person, by practice, can, therefore, obtain more or less expertness in this exercise; in which, though not apparently, the voice is still modified by the mouth and tongue; and it is in the concealment of this aid, that much of the perfection of ventriloquism lies.

But the distinctive character of ventriloquism consists in its imitations being performed by the voice seeming to come from the stomach: hence its name, from venter, the stomach, and loquor, to speak. Although the voice does not actually come from that region, in order to enable the ventriloquist to utter sounds from the larynx without moving the muscles of his face, he strengthens them by a powerful action of the abdominal muscles. Hence, he speaks by means of his stomach; although the throat is the real source from whence the sound proceeds. It should, however, be added, that this speaking distinctly, without any movement of the lips at all, is the highest perfection of ventriloquism, and has but rarely been attained. Thus, MM. St. Gille and Louis Brabant, two celebrated French ventriloquists, appeared to be absolutely mute while exercising their art, and no change in their countenances could be discovered.

It has lately been shown, that some ventriloquists have acquired by practice the power of exercising the veil of the palate in such a manner, that, by raising or depressing it, they dilate or contract the inner nostrils. If they are closely contracted, the sound produced is weak, dull, and seems to be more or less distant; if, on the contrary, these cavities are widely dilated, the sound will be strengthened, the voice become loud, and apparently close to us.

Another of the secrets of ventriloquism, is the uncertainty with respect to the direction of sounds. Thus, if we place a man and a child in the same angle of uncertainty, and the man speaks with the accent of a child, without any corresponding motion in his mouth or face, we shall necessarily believe that the voice comes from the child. In this case, the belief is so strengthened by the imagination; for if we were directed to a statue, as the source from which we were to expect sounds to issue, we should still be deceived, and refer the sounds to the lifeless stone or marble. This illusion will be greatly assisted by the voice being totally different in tone and character from that of the man from whom it really comes. Thus, we see how easy is the deception when the sounds are required to proceed from any given object, and are such as they actually yield.

The ventriloquists of our time, as M. Alexander and M. Fitz-James, have carried their art still further. They have not only spoken by the muscles of the throat and the abdomen, without moving those of the face, but have so far overcome the uncertainty of sound, as to become acquainted with modifications of distance, obstruction, and other causes, so to imitate them with the greatest accuracy. Thus, each of these artists has succeeded in carrying on a dialogue; and each, in his own single person and with his own single voice, has represented a scene apparently with several actors. These ventriloquists have likewise possessed such power over their faces and figures, that, aided by rapid changes of dress, their personal identity has scarcely been recognised among the range of personations.

Vocal imitations are much less striking and ingenious than the feats of ventriloquism. Extraordinary varieties of voice may be produced, by speaking with a more acute or grave pitch than usual, and by different contractions of the mouth. Thus may be imitated the grinding of cutlery on a wheel, the sawing of wood, the frying of a pancake, the uncorking of a bottle, and the gurgling noise in emptying its contents.

FLASHES OF LIGHT UPON REVOLVING WHEELS.

PROVIDE a circle of card-board, six inches in diameter; divide it into sixteen parts, and paint them alternately red and black. Provide a second circle or disc of the same size, and paint on it, in large characters, the words “At rest,” on a white ground. Connect both discs with the simple apparatus for causing them to turn round, used in the construction of a toy windmill. Next fill a basin with water, and provide a few small pieces of phosphuret of lime: darken the room, hold the discs over the basin, and turn them round; let the phosphuret of lime be put into the water, and bubbles of light will rise to its surface. If they come up slowly, both discs will appear stationary during their turning round; but when the bubbles come up quickly, the black and red spaces will exhibit a dancing motion, and sometimes two black spaces will seem joined into one, to the exclusion of the intervening red, and vice versâ: the words on the second disc will also cross each other in various directions, when the flashes of light interfere; and, in both cases, confusion will be excited by an impression being made on the retina, before preceding impressions have departed.

DECOMPOSITION OF LIGHT.

Sir Isaac Newton first divided a white ray of light, and found it to consist of an assemblage of coloured rays, which formed an image upon a wall, and in which were displayed the following colours: red, orange, yellow, green, blue, indigo, and violet. Sir Isaac then showed that these seven colours, when again put together or combined, recomposed white light. This may be proved by painting a card wheel in circles with the above colours, and whirling it rapidly upon a pin, when it will appear white.

Light may also be decomposed by the following beautiful experiment: Form a tube about ten inches long and one inch in diameter, of paper, one side of which is of a bright blue colour. This may be done by wrapping the paper once round a cylinder of wood, and securing the edges of the paper with paste. The coloured side of the paper must be the interior of the tube. Apply this tube to one eye, the other being closed, and on looking at the ceiling, a circular orange spot will be seen, which is the result of decomposition: the white light from the ceiling enters the tube, the blue is retained, and the red and yellow rays enter the eye, and produce the impression of orange.

SOLAR REFRACTION.

The theory of solar refraction may be beautifully illustrated as follows: Put a shilling into a basin, and pour some water on it, when the silver will be refracted through the medium; and, if the vessel be filled, you may withdraw to any distance from which the surface of the water will be visible, and, by the refraction from it, you can still observe the shilling.

INCANTATIONS.

Dissolve crystals of nitrate of copper in spirit of wine; light the solution, and it will burn with a beautiful emerald-green flame: pieces of sponge soaked in this spirit, lighted and suspended by fine wires, produce the lambent green flames now so common in incantation scenes: strips of flannel saturated with it, and applied round copper swords, tridents, &c., produce, when lighted, the flaming swords and fire-forks, brandished by the demons in such scenes: indeed, the chief consumption of nitrate of copper is for these purposes.

TO IMITATE THE LIGHT OF THE SEA.

It is well known, that on dark, stormy nights, the sea emits a brilliant light, the effect of which may be thus imitated. Scrape off four drams of the substance of putrefying fish, as whiting, herring, or mackerel, and put it into a white glass bottle, containing two ounces of sea-water, or of pure water with two drams of common salt dissolved in it; set the bottle in a dark place, and in three days a ring of light will be seen on the surface of the liquid, and the whole, if shaken, will become luminous, and continue so for some time. If it be set in a warm place, the light will be brighter; if the liquid be frozen, the light will disappear, but will re-appear on being thawed.

If more salt be added to the solution, the light will disappear, but instantly burst forth from absolute darkness by dilution with water. Lime-water, common water, beer, acids, even very dilute alkaline leys, as pearl-ash or soda and water, will permanently extinguish this spontaneous light.

INSTANTANEOUS LIGHTS.

The oxygenated, or chlorate matches, are first dipped in melted sulphur, and then tipped with a paste made of chlorate of potass, sulphur, and sugar, mixed with gum-water, and coloured with vermilion: frankincense and camphor are sometimes mixed with the composition, and the wood of the match is pencil-cedar, so that a fragrant odour is diffused from the matches in burning. To obtain light, a match is very lightly dipped in a bottle containing a little asbestos soaked in oil of vitriol.

Lucifers consist of chips of wood tipped with a paste of chlorate of potass mixed with sulphuret of antimony, starch, and gum-water: when a match is pinched between the folds of glass-paper, and suddenly drawn out, a light is instantly obtained.

Prometheans consist of small rolls of waxed paper, in one end of which is a minute quantity of vitriol, in a glass bulb, sealed up, and surrounded with chlorate of potass: when the end thus prepared is pressed so as to break the bulb, the vitriol comes in contact with the composition, and produces light instantly.

For cigar-smokers, Prometheans are made with touch-paper; this ignites from the composition, and glows without flame, like a slow match; and as the wind will not extinguish it, a dry cigar may be readily lighted at it.

Lucifers and Prometheans must be used with caution, and should never be carelessly left about: by letting them fall upon a sanded floor, and being accidentally trod upon, they may take fire, and thus do great mischief.

TO COLOUR THE FLAME OF A CANDLE.

Take a piece of packthread, or cotton thread, boil it in clean water to free it from saline particles, and dry it; wet one end, and take upon it a little of either of the salts hereafter named, in fine powder, or strong solution. Then dip the wetted end of the thread into the cup of a burning wax candle, and apply it to the exterior of the flame, not quite touching the luminous part, but so as to be immersed in the cone of invisible but intensely heated air which envelopes it. Immediately, an irregular sputtering combustion of the wax on the thread will take place, and the invisible cone of heat will be rendered luminous, with a peculiarly coloured light, according to the salt employed.