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NATURAL MAGIC BY JOHN NEVIL MASKELYNE.
II,—OPTICAL ILLUSIONS.
IN a previous paper it has been shown that the art of the magician chiefly consists in skilful use of nature’s wonders. This is specially the case in regard to the illusions effected through knowledge of optical laws and appliances, with which the majority of people are not acquainted.
For the purposes of the magician no instrument is more valuable than the concave speculum, a mirror in shape like the inside of a watch-glass.
To illustrate one of the many forms of illusion obtainable by its aid, let a partition, as in Fig. 1, have an aperture in it on a level with the eye of the spectator, and behind the screen place a concave mirror (A) reflecting the inverted skeleton, placed in
a strong light at n. This will appear to the person in front in an upright position at the opening (c), and upon his advancing towards it the spectre will vanish altogether.
By a combination of plane mirrors — ordinary looking-glass, having perfectly flattened and parallel surfaces—many curious effects may be produced.
Suppose a room divided by partitions, as in Fig. 2,
in which are two apertures, some five feet from the
ground, at A, B. The aperture at B is filled in with a plain sheet of glass, and behind this a silvered
glass is arranged to run up and down upon pulleys.
To complete the deception, a gilt frame may be
placed round the opening, to give it the appearance
of a mirror hanging upon the wall. Now, the spectator at c, who looks towards this while the silvered
glass remains there, will see a reflection of himself, but if a curtain be drawn in front of the aperture, and, simultaneously, the mirror behind be raised above it, then, when the curtain is once more pulled aside, he will be astounded by the apparently magical transformation, for, by the aid of a mirror at D, placed at an angle of forty-five degrees, and which he cannot distinguish from the one in which he previously looked, ho will see, not his own reflection,
but that of his supposed (Darwinian) progenitor—
which is rather a reflection upon his manhood-—, whose image is transmitted along the dotted lines
from the mirror at r.
The preceding illusions are more fully explained
in Sir David Brewster’s admirable “Letters on
Natural Magic.”
Upon the principle of the latter optical deception
is the device by which one appears to look through a solid object. An elderly gentleman of my acquaintance was wont to say, with perfect truthfulness, that he could see as far through a millstone as most people. By the illusion in Fig. 3 ho might have been. persuaded that be actually looked right through the centre of a brick, for if the rays from a lighted candle at A enter a dark tube by the dotted lines, and strike on the mirror at n, they are again reflected in the mirrors at c, D, and z—all of them at the angle of forty-five degrees—and presented to the eye at r, as if the flame of the candle was seen through the brick G.
The use of concave and plane mirrors for magical purposes was superseded for a time by the more fertile field for illusion opened up by the magic- lantern, about the middle of the seventeenth century. It was introduced by Athanasius Kircher, a member of the Society of Jesus. In one of his numerous works, “Ars Magna Lucis et Unibrm,” he described one used by him in the Jesuits’ College at Rome. There is an engraving in which a room is seen divided by a partition. Upon one side of this is a lantern and the operator; on the other the spectators, and a screen to receive the images. The lantern is a large wooden box, with a door at the side and a chimney at the top; in front is a tube containing the lens and a frame for the pictures, which were painted upon glass; an oil-lamp, with a brass reflector, is inside the lamp. In the perfecting of this instrument Kircher seems to have received great assistance from a mathematician named Walgonstenius, who constructed many lanterns, and sold them to the Italian nobility, who were anxious to possess the wonderful novelty.
The Phantasmagoria, an improvement upon Kircher’s lantern, was introduced into Paris by one Robert, or Robertson, a conjuror, of Liege, about the year 1798; and into England by Philipstal, also a Frenchman, in. 1802. This instrument differed from Kircher’s in being made to run upon wheels, and was so readily brought close to, or removed from, the screen, causing the figures to grow larger or disappear altogether. The pictures on the glass, or “slider,” were also opaque, excepting those parts upon which the figures were painted, so that the figures were luminous upon a black ground, and produced a much greater effect than in the old style, where they were thrown upon the screen in a circle of light.
Another improvement in the magic-lantern was introduced in 1811, by Mr. Child, and is used for what are called Dissolving Views. This optical illusion when first brought into requisition for the spectral ship of Vanclerdecken, in the drama of the “Flying Dutchman,” at the Adelphi Theatre, caused great astonishment. In the Dissolving Views two reflectors are so placed as. to throw the images of two pictures upon the same part of the screen, where they gradually melt one into the other.
That optical arrangement, the Camera Obscura, literally the “Dark Chamber,” was the discovery of Baptista Porta, a Neapolitan philosopher. To the great astonishment of a circle of literary and scientific friends, he brought sea and landscapes into his darkened room. This was managed by arranging panoramic effects outside the house, where many a “painted ship upon a painted ocean” lay at anchor; and boys, concealed behind fictitious trees and mountains, started real animals, or pulled “property” ones about. Possibly that zoological curiosity, the elephant of the pantomimes (with a gentlemanly “super” at one shilling per night in the fore legs, and another equally favoured being in the other two), may have first seen the light in Baptista Porta’s back garden!
The well-known effects of the camera obscure may be simply obtained by closing the shutters of a room and leaving only one small hole by which light may enter. Images of objects will then be seen in all their natural colours, but inverted, upon any white surface opposite. The addition of a convex lens will increase the brilliancy of the phenomena, and an arrangement of mirrors restore the images to the natural erect position upon the screen.
The modern illusion known as “Pepper’s Ghost” has gone through several phases. Its effects are duo to the optical law that when a luminous ray falls upon a polished plane surface the reflection takes place on a plane perpendicular to the reflecting surface, and the incident and reflected rays form equal angles with it. This may be observed in the plate glass of such places as the Burlington Arcade, the polished windows of a first-class railway carriage as it rattles through a tunnel, or the well-cleaned windows of that humbler conveyance, a metropolitan tramway-car, as it goes its night journey to the suburbs, after the closing of the shops and all is dark without.
This beautiful production of distinct visions of solid bodies upon plain unsilvered glass waited a long time before it was utilised in the illusions of M. Robin, at Paris, and the Polytechnic “ghost.” In the earlier attempts in this country the person who undertook the role of spectre stood in a strong light at the side of the stage, the glass upon which the vision came being set in front of the audience at such an angle as to take upon it the reflection of the figure at the “wing,” which had a dark background of the same colour as that upon the stage. The difficulty in this instance was to get the phantom into a perpendicular position.
Another method, and one in very general use now, for “ghost” exhibitions, is shown in Fig. 4. The large glass (A) upon the stage is so arranged as to be quite invisible to the audience, its edges being hidden by painted foliage or other contrivances. The impersonators of the spectres lie upon their backs horizontally, below the level of the stage at n. Here they disport themselves, every look and gesture being faithfully reproduced by the glass above, where the images appear quite erect. The left band must always be used for the right, etc., as the image is reversed when presented to the spectators. The auditorium being dark, and the light upon the stage less vivid than that illuminating the figures below— in what is facetiously termed “the oven “—the phantoms are more distinctly risible to the audience than are the real actors, and at the same distance behind the glass as the originals are in front of it.
Those upon the stage cannot see the visions that “come like shadows, so depart,” therefore the positions to be occupied at certain times, when they
have to pass a sword or even walk through a ghost, has to be carefully arranged beforehand. Startling effects are also at the command of the exhibitor by keeping the stage dark so that a per. former, dressed exactly as the ghost below, cannot be seen. The bright light upon the figure beneath shows the vision distinctly, but this gradually subdued while, simultaneously, the lights upon the stage are raised, the ghost will appear to develop into the actor now visible behind the glass, and in the exact position occupied by the apparition.
Another, and perhaps the best method to work these illusions, is shown in Fig. 5. Here two glasses are seen, each placed at an angle of 450 The lower one (i) is a mirror, and throws the reflection of the performer at B upon the plain glass e, and the ghost appears upon the stage behind this at n. Here the performer can, by walking parallel to the glass, give the effect of the vision walking upon the stage. All the movements are natural, and the illusion is most complete.
This class of exhibition, indeed, appears marvellous to the uninitiated, and those who understand its principles cannot but admire the beautiful results. The illusions are capable of almost unlimited extension. One more may be mentioned, which produces great wonder in an audience, where a large black
board is placed unmistakably in their view, and a spectre hand writes in white characters upon it.
This is managed by having a duplicate board below the stage, so arranged that its shadow falls exactly over the one in view of the audience. Upon this duplicate black surface the performer writes with chalk, and, as all save his hand is covered by black cloth, and so blends with the black board above, the hand only appears to the spectators. This leaves the flesh-coloured stuffed gloves (the “materialised hands”) of the spirit media far behind!
Visions of real flesh and blood may sometimes be seen floating in the air, apparently unsupported. This is also an optical deception, as the performer stands upon the edge of a thick sheet of plate glass
which, its edges being carefully hidden, does not appear to the spectators.
One of the achievements of the Polytechnic was the head of Socrates, which appeared in the centre
of the stage without any body attached to it, and delivered a set speech “ with good accent and discretion.” The sensational effect was produced by simple means, the actor’s head being merely thrust through a hole in a silvered glass plate, which, by a skilful arrangement of lights and drapery, was invisible to the audience.
The trick called “Palingenesia” was upon the same principle, and the limbs to be severed from the body were dummies fixed in holes in the glass, while the real limbs of the performer reposed in perfect security behind it.
The illusion of the “sweet little cherubs “who sat (or, rather, floated, sitting being an impossibility under the circumstances) “up aloft,” at the Polytechnic, after the celebrated picture by Sir Joshua Reynolds, were produced by the same means; but might also have been arranged as successfully by reflections from some interesting children engaged for the occasion, whose bodies, being considered superfluous for the characters they were to represent, could be hidden behind a dark cloth, through which their heads peered. This matching in colour the background of the stage, and skilful blending with it in the reflection, would assist the illusion.
Having briefly indicated the leading points in the public use of optical illusions, I may name a few for private examination, alike curious and instructive. A deformed, or an amorphous, drawing upon a flat surface can be so arranged that, though it have no shape or meaning to the eye, it shall yet be reflected, in perfect form and proportion, on the convex side of a cylindrical mirror placed in the proper focus, or the picture may be painted on the oonvex surface, and reflected on the plane. An ordinary statuette, say of a child, can be so distorted by the use of a prism with a small refracting angle, that the head may be placed upon its breast, like those
men -whose heads
Do grow beneath their shoulders ;“
or apparently severed from the body altogether.
If an intaglio (a sunken device, as an ordinary seal) be held towards a window, those parts of it farthest from the window will receive most light; while an impression of the seal (which may be called the cameo, or raised device), if similarly placed, will receive more light upon the side nearer to the window. This is, of course, obvious. Now view the seal through a compound microscope, or achromatic telescope, and you invert the position of the object, and find the depressed portions have become elevated, and appear exactly as the mprcc8on of the seal is to the naked eye.
But the eye is literally “open” to deception without employing such instruments. Its power of retaining impressions induces it to see that which is not; thus a lighted stick rapidly twirled round looks like a circle of fire, and bodies in swift rotation appear stationary. Natural causes produce other curious effects, for instance, sustained vision of objects seen obliquely is impossible. This may be demonstrated by placing a pea upon a green cloth, and a narrow strip of white paper at some distance from it, but so as to be perfectly clear by indirect vision. Gazing steadily upon the pea, you will notice that shortly a part, or possibly the whole, of the white paper will vanish, the green cloth seeming to cover the spot upon which it lay. The paper may be again visible, after an interval, and once more fade away.
Atmospherical phenomena account for many ghosts, and are almost as guilty in this direction as the finger-posts at country cross-roads, that have scared so many rustic Tony Lumpkins, with their white outstretched arms, standing grimly pointing in the deserted lanes at night. The refractive power of the air produces the extraordinary illusions known as the mirage. These singular and magical effects have been seen in nearly all parts of the world. Humboldt, during his travels in South America, witnessed from Oumana the islands of Baracha and Licuita apparently floating in the air. Upon the coast of Africa, towards evening, the “look-out” upon a schooner observed the tall masts of another ship rise slowly from the sea. They appeared distinctly, and other parts came up above the horizon until the whole vessel was seen to first rest upon the water, and then rise above it until the hull was plainly visible. Mariners are often superstitious, and viewed such phenomena in the light of “phantom ships;” but it was the coldness of the sea and the air above it gradually decreasing in density that caused the illusion. Among the marvels of the Paleocrystic Sea are frequent magical effects where glittering icebergs appear to float, inverted, in the air, where ships are seen keel upwards and magnified in size, and ice-floes assume the appearance of fair cities, gay with “cloud-capped •towers and gorgeous palaces.” This phenomenon, called “the Enchanted Coast,” was witnessed by Mr. Scoresby, on hi voyage to Greenland in 1822, and he also perceived an inverted ship in the air, which was afterwards found to be the image of his father’s vessel, at that time thirty miles distant.
The “Fata Morgana,” or “Castles of the Fairy Morgana,” seen in the Straits of Messina, like the visionary cities of the Arctic regions, present pictures of hill and dell, towns, and people, ever swiftly changing, as the forms in a kaleidoscope, and these effects arise from unequal aerial refraction.
Sometimes spectral phenomena are produced by clouds. The good people of Florence were startled by seeing, floating above the city, a great figure of an angel, and for some hours they were duped into a belief in a miracle, until it was found that the shadow of a gilded angel surmounting the Duomo was thrown upon the cloud by the rays of the setting sun. Hogg, the “Ettrick Shepherd,” mentions the astonishment created by a similar illusion, in which the vision of a man, attended by an enormous dog, was seen in the sky. Both these effects are due to the same cause as the spectre of the Brocken (one of the loftiest of the Hartz Mountains in Hanover), where colossal figures in the air imitate the movements of the observers. These cloud phantoms are not inverted. The old adage, therefore, that “seeing is believing,” must not be accepted as a truism, the eye, indeed, wonderful as are its powers of taking in form, size, position, and colour, can yet be, in its turn, “taken in” very easily, and is, as we see every day, a most innocent and gullible organ. Our eyes are frequently made “the fools o’ the other senses,” conjuring up, when the mind is ill at ease, or when bodily ailments afflict us, apparitions as genuine to all appearance as the dagger of Macbeth. In our dreams there are no objects presented to the eye, though we apparently see many and in great detail; and they frequently create so great an impression upon the mind that the scenes are re-enacted in the waking moments. Spinoza avows that one morning, when starting from a dream, the vision was yet as vivid as though palpable to the touch. It is similar illusion that “informs the eye” of the misanthrope. In his waking dreams he sees not the landscape spread before him; his eye—slave of the mind— raises phantasms unsubstantial, yet terribly real. So is it with other passions and moods of the human spirit.
Overwork and anxiety, too, readily induce such phenomena. It is related of Sir Joshua Reynolds that “when, after being many hours occupied in painting, he walked into the street, the lamp-posts seemed to him to be trees, and the men and women moving shrubs.” Such visual peculiarities are warnings to the overtaxed brain, being symptoms of cerebral disorder, that might end in mental disease. We refer to these things as proofs that the sense of sight is easily open to deception from natural causes, apart from the tricks of the “ magician” and “illusionist.”