Science used as an instrument of imposture--Deceptions with plane
and concave mirrors practised by the ancients--The magician’s
mirror--Effects of concave mirrors--Aërial images--Images on
smoke--Combination of mirrors for producing pictures from living
objects--The mysterious dagger--Ancient miracles with concave
mirrors--Modern necromancy with them, as seen by Cellini--Description
and effects of the magic lantern--Improvements upon it--Phantasmagoric
exhibitions of Philipstall and others--Dr. Young’s arrangement
of lenses, &c., for the Phantasmagoria--Improvements
suggested--Catadioptrical phantasmagoria for producing the
pictures from living objects--Method of cutting off parts of the
figures--Kircher’s mysterious hand-writing on the wall--His hollow
cylindrical mirror for aërial images--Cylindrical mirror for
re-forming distorted pictures--Mirrors of variable curvature for
producing caricatures.
In the preceding observations man appears as the victim of his own
delusions--as the magician unable to exercise the spirits which he
has himself called into being. We shall now see him the dupe of
preconcerted imposture--the slave of his own ignorance--the prostrate
vassal of power and superstition. I have already stated that the
monarchs and priests of ancient times carried on a systematic plan
of imposing upon their subjects--a mode of government which was in
perfect accordance with their religious belief: but it will scarcely be
believed that the same delusions were practised after the establishment
of Christianity, and that even the Catholic sanctuary was often the
seat of these unhallowed machinations. Nor was it merely the low and
cunning priest who thus sought to extort money and respect from the
most ignorant of his flock: bishops and pontiffs themselves wielded
the magician’s wand over the diadem of kings and emperors, and, by
the pretended exhibition of supernatural power, made the mightiest
potentates of Europe tremble upon their thrones. It was the light of
science alone which dispelled this moral and intellectual darkness,
and it is entirely in consequence of its wide diffusion that we live
in times when sovereigns seek to reign only through the affections of
their people, and when the minister of religion asks no other reverence
but that which is inspired by the sanctity of his office and the purity
of his character.
It was fortunate for the human race that the scanty knowledge of former
ages afforded so few elements of deception. What a tremendous engine
would have been worked against our species by the varied and powerful
machinery of modern science! Man would still have worn the shackles
which it forged, and his noble spirit would still have groaned beneath
its fatal pressure.
There can be little doubt that the most common, as well as the most
successful, impositions of the ancients were of an optical nature,
and were practised by means of plane and concave mirrors. It has been
clearly shown by various writers that the ancients made use of mirrors
of steel, silver, and a composition of copper and tin, like those now
used for reflecting specula. It is also very probable, from a passage
in Pliny, that glass mirrors were made at Sidon; but it is evident,
that, unless the object presented to them was illuminated in a very
high degree, the images which they formed must have been very faint and
unsatisfactory. The silver mirrors, therefore, which were universally
used, and which are superior to those made of any other metal, are
likely to have been most generally employed by the ancient magicians.
They were made to give multiplied and inverted images of objects, that
is, they were plane, polygonal or many-sided, and concave. There is
one property, however, mentioned by Aulus Gellius, which has given
unnecessary perplexity to commentators. He states that there were
specula, which, when put in a particular place, gave no images of
objects, but when carried to another place, recovered their property
of reflection.[7] M. Salverte is of opinion that, in quoting Varro,
Aulus Gellius was not sufficiently acquainted with the subject, and
erred in supposing that the phenomenon depended on the _place_ instead
of the position of the mirror; but this criticism is obviously made
with the view of supporting an opinion of his own--that the property
in question may be analogous to the phenomenon of polarised light,
which, at a certain angle, refuses to suffer reflexion from particular
bodies. If this idea has any foundation, the mirror must have been of
glass or some other body not metallic, or, to speak more correctly,
there must have been _two_ such mirrors, so nicely adjusted not only
to one another, but to the light incident upon each, that the effect
could not possibly be produced but by a philosopher thoroughly
acquainted with the modern discovery of the polarisation of light
by reflexion. Without seeking for so profound an explanation of the
phenomenon, we may readily understand how a silver mirror may instantly
lose its reflecting power in a damp atmosphere, in consequence of the
precipitation of moisture upon its surface, and may immediately recover
it when transported into drier air.
[7] _Ut speculum in loco certo positum nihil imaginet; aliorsum
translatum faciat imagines._ Aul. Gel. Noct. Attic., lib. xvi., cap.
18.
[Illustration: _Fig. 3._]
One of the simplest instruments of optical deception is the plane
mirror, and when two are combined for this purpose it has been called
the magician’s mirror. An observer in front of a plane mirror sees a
distinct image of himself; but if two persons take up a mirror, and
if the one person is as much to one side of a line perpendicular to
the middle of it as the other is to the other side, they will see each
other, but not themselves. If we now suppose MC, CD, NC, CD to be the
partitions of two adjacent apartments let square openings be made in
the partitions at A and B, above five feet above the floor, and let
them be filled with plate glass, and surrounded with a picture frame,
so as to have the appearance of two mirrors. Place two mirrors, E, F,
one behind each opening at A and B, inclined 45° to the partition MN,
and so large that a person looking into the plates of glass at A and
B will not see their edges. When this is done it is obvious that a
person looking into the mirror A will not see himself, but will see any
person or figure placed at B. If he believes that he is looking into a
common mirror at A, his astonishment will be great at seeing himself
transformed into another person, or into any living animal that may be
placed at B. The success of this deception would be greatly increased
if a plane mirror, suspended by a pulley, could be brought immediately
behind the plane glass at A, and drawn up from it at pleasure. The
spectator at A, having previously seen himself in this moveable mirror,
would be still more astonished when he afterwards perceived in the same
place a face different from his own. By drawing the moveable mirror
half up, the spectator at A might see half of his own face joined to
half of the face placed at B; but in the present day the most ignorant
persons are so familiar with the properties of a looking-glass, that
it would be very difficult to employ this kind of deception with the
same success which must have attended it in a more illiterate age. The
optical reader will easily see that the mirror F and the apartment NCD
are not absolutely necessary for carrying on this deception; for the
very same effects will be produced if the person at B is stationed at
G, and looks towards the mirror F in the direction GF. As the mirror
F, however, must be placed as near to A as possible, the person at G
would be too near the partition CN, unless the mirror F was extremely
large.
The effect of this and every similar deception is greatly increased
when the persons are illuminated with a strong light, and the rest of
the apartment as dark as possible; but whatever precautions are taken,
and however skilfully plane mirrors are combined, it is not easy to
produce with them any very successful illusions.
The concave mirror is the staple instrument of the magician’s cabinet,
and must always perform a principal part in all optical combinations.
In order to be quite perfect, every concave mirror should have its
surface elliptical, so that if any object is placed in one focus of the
ellipse, an inverted image of it will be formed in the other focus.
This image, to a spectator rightly placed, appears suspended in the
air, so that if the mirror and the object are hid from his view, the
effect must appear to him almost supernatural.
The method of exhibiting the effect of concave mirrors most
advantageously is shown in Fig. 4, where CD is the partition of a
room having in it a square opening EF, the centre of which is about
five feet above the floor. This opening might be surrounded with a
picture-frame, and a painting which exactly filled it might be so
connected with a pulley that it could be either slipped aside, or
raised so as to leave the frame empty. A large concave mirror MN is
then placed in another apartment, so that when any object is placed at
A, a distinct image of it may be formed in the centre of the opening
EF. Let us suppose this object to be a plaster cast of any object made
as white as possible, and placed in an _inverted_ position at A. A
strong light should then be thrown upon it by a powerful lamp, the rays
of which are prevented from reaching the opening EF. When this is done,
a spectator placed at O will see an erect image of the statue at B,
the centre of the opening, standing in the air, and differing from the
real statue only in being a little larger, while the apparition will
be wholly invisible to other spectators placed at a little distance on
each side of him.
[Illustration: _Fig. 4._]
If the opening EF is filled with smoke, rising either from a
chafing-dish, in which incense is burnt, or made to issue in clouds
from some opening below, the image will appear in the middle of the
smoke depicted upon it as upon a ground, and capable of being seen by
those spectators who could not see the image of the air. The rays of
light, in place of proceeding without obstruction to an eye at O, are
reflected as it were from those minute particles of which the smoke
is composed, in the same manner as a beam of light is rendered more
visible by passing through an apartment filled with dust or smoke.
It has long been a favourite experiment to place at A a white and
strongly illuminated human skull, and to exhibit an image of it amid
the smoke of a chafing-dish at B; but a more terrific effect would be
produced if a small skeleton suspended by invisible wires were placed
as an object at A. Its image suspended in the air at B, or painted upon
smoke, could not fail to astonish the spectator.
The difficulty of placing a living person in an inverted position,
as an object at A, has no doubt prevented the optical conjuror from
availing himself of so admirable a resource; but this difficulty may be
removed by employing a second concave mirror. The second mirror may be
so placed as to reflect towards MN the rays proceeding from an erect
living object, and to form an inverted image of this object at A. An
erect image of this inverted image will then be formed at B, either
suspended in the air, or depicted upon a wreath of smoke. This aërial
image will exhibit the precise form and colours and movements of the
living object, and it will maintain its character as an apparition if
any attempt is made by the spectator to grasp its unsubstantial fabric.
A deception of an alarming kind, called the _Mysterious dagger_,
has been long a favourite exhibition. If a person with a drawn and
highly polished dagger, illuminated by a strong light, stands a
little farther from a concave mirror than its principal focus, he
will perceive in the air between himself and the mirror an inverted
and diminished image of his own person, with the dagger similarly
brandished. If he aims the dagger at the centre of the mirrors
concavity, the two daggers will meet point to point, and, by pushing it
still farther from him towards the mirror, the imaginary dagger will
strike at his heart. In this case it is necessary that the direction of
the real dagger coincides with a diameter of the sphere of which the
mirror is a part; but if its direction is on one side of that diameter,
the direction of the imaginary dagger will be as far on the other side
of the diameter, and the latter will aim a blow at any person who is
placed in the proper position for receiving it. If the person who bears
the real dagger is therefore placed behind a screen, or otherwise
concealed from the view of the spectator, who is made to approach to
the place of the image, the thrust of the polished steel at his breast
will not fail to produce a powerful impression. The effect of this
experiment would no doubt be increased by covering with black cloth
the person who holds the dagger, so that the image of his hand only
should be seen, as the inverted picture of him would take away from the
reality of the appearance. By using two mirrors, indeed, this defect
might be remedied, and the spectator would witness an exact image of
the assassin aiming the dagger at his life.
The common way of making this experiment is to place a basket of fruit
above the dagger, so that a distinct aërial image of the fruit is
formed in the focus of the mirror. The spectator, having been desired
to take some fruit from the basket, approaches for that purpose, while
a person properly concealed withdraws the real basket of fruit with one
hand, and with the other advances the dagger, the image of which being
no longer covered by the fruit, strikes at the body of the astonished
spectator.
The powers of the concave mirror have been likewise displayed in
exhibiting the apparition of an absent or deceased friend. For this
purpose, a strongly illuminated bust or picture of the person is
placed before the concave mirror, and a distinct image of the picture
will be seen either in the air or among smoke, in the manner already
described. If the background of the picture is temporarily covered with
lamp-black, so that there is no light about the picture but what falls
upon the figure, the effect will be more complete.
As in all experiments with concave mirrors, the size of the aërial
image is to that of the real object as their distances from the mirror,
we may, by varying the distance of the object, increase or diminish the
size of the image. In doing this, however, the distance of the image
from the mirror is at the same time changed, so that it would quit the
place most suitable for its exhibition. This defect may be removed by
simultaneously changing the place both of the mirror and the object, so
that the image may remain stationary, expanding itself from a luminous
spot to a gigantic size, and again passing through all intermediate
magnitudes, till it vanishes in a cloud of light.
Those who have studied the effects of concave mirrors of a small
size, and without the precautions necessary to ensure deception,
cannot form any idea of the magical effect produced by this class of
optical apparitions. When the instruments of illusion are themselves
concealed,--when all extraneous lights but those which illuminate
the real object are excluded,--when the mirrors are large and
well-polished, and truly formed,--the effect of the representation on
ignorant minds is altogether overpowering; while even those who know
the deception, and perfectly understand its principles, are not a
little surprised at its effects. The inferiority in the effects of a
common concave mirror to that of a well-arranged exhibition is greater
even than that of a perspective picture, hanging in an apartment, to
the same picture exhibited under all the imposing accompaniments of a
dioramic representation.
It can scarcely be doubted, that a concave mirror was the principal
instrument by which the heathen gods were made to appear in the ancient
temples. In the imperfect accounts which have reached us of these
apparitions, we can trace all the elements of an optical illusion. In
the ancient temple of Hercules at Tyre, Pliny mentions that there was
a seat made of a consecrated stone, “from which the gods easily rose.”
Esculapius often exhibited himself to his worshippers in his temple
at Tarsus; and the temple of Enguinum in Sicily was celebrated as the
place where the goddesses exhibited themselves to mortals. Iamblichus
actually informs us, that the ancient magicians caused the gods to
appear among the vapours disengaged from fire; and when the conjuror
Maximus terrified his audience by making the statue of Hecate laugh,
while in the middle of the smoke of burning incense, he was obviously
dealing with the image of a living object dressed in the costume of the
sorceress.
The character of these exhibitions in the ancient temples is so
admirably depicted in the following passage of Damascius, quoted by M.
Salverte, that we recognise all the optical effects which have been
already described. “In a manifestation,” says he, “which ought not to
be revealed ... there appeared on the wall of the temple a mass of
light, which at first seemed to be very remote; it transformed itself,
in coming nearer, into a face evidently divine and supernatural, of
a severe aspect, but mixed with gentleness, and extremely beautiful.
According to the institutions of a mysterious religion, the
Alexandrians honoured it as Osiris and Adonis.”
Among more modern examples of this illusion, we may mention the case of
the Emperor Basil of Macedonia. Inconsolable at the loss of his son,
this sovereign had recourse to the prayers of the Pontiff Theodore
Santabaren, who was celebrated for his power of working miracles. The
ecclesiastical conjuror exhibited to him the image of his beloved
son, magnificently dressed and mounted upon a superb charger: the
youth rushed towards his father, threw himself into his arms, and
disappeared. M. Salverte judiciously observes, that this deception
could not have been performed by a real person who imitated the figure
of the young prince. The existence of this person, betrayed by so
remarkable a resemblance, and by the trick of the exhibition, could not
fail to have been discovered and denounced, even if we could explain
how the son could be so instantaneously disentangled from his father’s
embrace. The emperor, in short, saw the aërial image of a picture
of his son on horseback; and as the picture was brought nearer the
mirror, the image advanced into his arms, when it of course eluded his
affectionate grasp.
These and other allusions to the operations of the ancient magic,
though sufficiently indicative of the methods which were employed, are
too meagre to convey any idea of the splendid and imposing exhibitions
which must have been displayed. A national system of deception,
intended as an instrument of government, must have brought into
requisition not merely the scientific skill of the age, but a variety
of subsidiary contrivances calculated to astonish the beholder, to
confound his judgment, to dazzle his senses, and to give a predominant
influence to the peculiar imposture which it was thought desirable
to establish. The grandeur of the means may be inferred from their
efficacy, and from the extent of their influence.
This defect, however, is, to a certain degree, supplied by an account
of a modern necromancy, which has been left us by the celebrated
Benvenuto Cellini, and in which he himself performed an active part.
“It happened,” says he, “through a variety of odd accidents, that I
made acquaintance with a Sicilian priest, who was a man of genius, and
well versed in the Latin and Greek authors. Happening one day to have
some conversation with him when the subject turned upon the art of
necromancy, I, who had a great desire to know something of the matter,
told him, that I had all my life felt a curiosity to be acquainted with
the mysteries of this art.
“The priest made answer, ‘that the man must be of a resolute and
steady temper who enters upon that study.’ I replied, ‘that I had
fortitude and resolution enough, if I could but find an opportunity.’
The priest subjoined, ‘If you think you have the heart to venture, I
will give you all the satisfaction you can desire.’ Thus we agreed
to enter upon a plan of necromancy. The priest one evening prepared
to satisfy me, and desired me to look out for a companion or two. I
invited one Vincenzio Romoli, who was my intimate acquaintance: he
brought with him a native of Pistoia, who cultivated the black art
himself. We repaired to the Colosseo, and the priest, according to the
custom of necromancers, began to draw circles upon the ground, with
the most impressive ceremonies imaginable: he likewise brought hither
asafœtida, several precious perfumes, and fire, with some compositions
also, which diffused noisome odours. As soon as he was in readiness,
he made an opening to the circle, and having taken us by the hand,
ordered the other necromancer, his partner, to throw the perfumes
into the fire at a proper time, entrusting the care of the fire and
perfumes to the rest; and thus he began his incantations. This ceremony
lasted above an hour and a half, when there appeared several legions
of devils, insomuch that the amphitheatre was quite filled with them.
I was busy about the perfumes, when the priest, perceiving there was
a considerable number of infernal spirits, turned to me and said,
‘Benvenuto, ask them something.’ I answered, ‘Let them bring me into
the company of my Sicilian mistress Angelica.’ That night he obtained
no answer of any sort; but I had received great satisfaction in having
my curiosity so far indulged. The necromancer told me it was requisite
we should go a second time, assuring me that I should be satisfied in
whatever I asked; but that I must bring with me a pure, immaculate boy.
“I took with me a youth who was in my service, of about twelve years of
age, together with the same Vincenzio Romoli, who had been my companion
the first time, and one Agnolino Gaddi, an intimate acquaintance, whom
I likewise prevailed on to assist at the ceremony. When we came to the
place appointed, the priest having made his preparations as before,
with the same and even more striking ceremonies, placed us within the
circle, which he had likewise drawn with a more wonderful art and in a
more solemn manner than at our former meeting. Thus, having committed
the care of the perfumes and the fire to my friend Vincenzio, who was
assisted by Agnolino Gaddi, he put into my hand a pintaculo or magical
chart, and bid me turn it towards the places that he should direct me;
and under the pintaculo I held the boy. The necromancer, having begun
to make his tremendous invocations, called by their names a multitude
of demons who were the leaders of the several legions, and questioned
them, by the power of the eternal uncreated God, who lives for ever,
in the Hebrew language, as likewise in Latin and Greek; insomuch that
the amphitheatre was almost in an instant filled with demons more
numerous than at the former conjuration. Vincenzio Romoli was busied
in making a fire, with the assistance of Agnolino, and burning a great
quantity of precious perfumes. I, by the directions of the necromancer,
again desired to be in the company of my Angelica. The former thereupon
turning to me said,--’Know, they have declared that, in the space of a
month, you shall be in her company.’
“He thus requested me to stand resolutely by him, because the legions
were now above a thousand more in number than he had designed; and
besides, these were the most dangerous; so that, after they had
answered my question, it behoved him to be civil to them, and dismiss
them quietly. At the same time the boy under the pintaculo was in a
terrible fright, saying, that there were in that place a million of
fierce men, who threatened to destroy us; and that, moreover, four
armed giants of enormous stature were endeavouring to break into our
circle. During this time, whilst the necromancer, trembling with fear,
endeavoured by mild and gentle methods to dismiss them in the best way
he could, Vincenzio Romoli, who quivered like an aspen leaf, took care
of the perfumes. Though I was as much terrified as any of them, I did
my utmost to conceal the terror I felt; so that I greatly contributed
to inspire the rest with resolution; but the truth is, I gave myself
over for a dead man, seeing the horrid fright the necromancer was in.
The boy placed his head between his knees and said, ‘In this posture
will I die; for we shall all surely perish.’ I told him that all these
demons were under us, and what he saw was smoke and shadow; so bid
him hold up his head and take courage. No sooner did he look up than
he cried out, ‘The whole amphitheatre is burning, and the fire is
just falling upon us.’ So covering his eyes with his hands, he again
exclaimed, ‘that destruction was inevitable, and desired to see no
more.’ The necromancer entreated me to have a good heart, and take
care to burn proper perfumes; upon which I turned to Romoli, and bid
him burn all the most precious perfumes he had. At the same time I
cast my eye upon Agnolino Gaddi, who was terrified to such a degree
that he could scarce distinguish objects, and seemed to be half dead.
Seeing him in this condition, I said, ‘Agnolino, upon these occasions
a man should not yield to fear, but should stir about and give his
assistance, so come directly and put on some more of these.’ The
effects of poor Agnolino’s fear were overpowering. The boy, hearing
a crepitation, ventured once more to raise his head, when, seeing me
laugh, he began to take courage, and said ‘that the devils were flying
away with a vengeance.’
“In this condition we stayed, till the bell rang for morning prayers.
The boy again told us, that there remained but few devils, and these
were at a great distance. When the magician had performed the rest of
his ceremonies, he stripped off his gown, and took up a wallet full of
books which he had brought with him.
“We all went out of the circle together, keeping as close to each other
as we possibly could, especially the boy, who had placed himself in
the middle, holding the necromancer by the coat, and me by the cloak.
As we were going to our houses in the quarter of Banchi, the boy told
us that two of the demons whom we had seen at the amphitheatre went on
before us leaping and skipping, sometimes running upon the roofs of the
houses, and sometimes upon the ground. The priest declared, that though
he had often entered magic circles, nothing so extraordinary had ever
happened to him. As we went along, he would fain persuade me to assist
with him at consecrating a brook, from which, he said, we should derive
immense riches; we should then ask the demons to discover to us the
various treasures with which the earth abounds, which would raise us to
opulence and power; but that these love-affairs were mere follies, from
whence no good could be expected. I answered, ‘that I would readily
have accepted his proposal, if I understood Latin.’ He redoubled his
persuasions, assuring me, that the knowledge of the Latin language
was by no means material. He added, that he could have Latin scholars
enough, if he had thought it worth while to look out for them, but that
he could never have met with a partner of resolution and intrepidity
equal to mine, and that I should by all means follow his advice. Whilst
we were engaged in this conversation we arrived at our respective
houses, and all that night dreamt of nothing but devils.”
It is impossible to peruse the preceding description without being
satisfied that the legions of devils were not produced by any influence
upon the imaginations of the spectators, but were actual optical
phantasms, or the images of pictures or objects produced by one or
more concave mirrors or lenses. A fire is lighted, and perfumes and
incense are burnt, in order to create a ground for the images, and the
beholders are rigidly confined within the pale of the magic circle. The
concave mirror and the objects presented to it having been so placed
that the persons within the circle could not see the aërial image of
the objects by the rays deeply reflected from the mirror, the work of
deception was ready to begin. The attendance of the magician upon his
mirror was by no means necessary. He took his place along with the
spectators within the magic circle. The images of the devils were all
distinctly formed in the air immediately above the fire, but none of
them could be seen by those within the circle. The moment, however,
that perfumes were thrown into the fire to produce smoke, the first
wreath of smoke that rose through the place of one or more of the
images, would reflect them to the eyes of the spectator, and they could
again disappear if the wreath was not followed by another. More and
more images would be rendered visible as new wreaths of smoke arose,
and the whole group would appear at once when the smoke was uniformly
diffused over the place occupied by the images.
The “compositions which diffused noisome odours” were intended to
intoxicate or stupify the spectators, so as to increase their liability
to deception, or to add to the real phantasms which were before their
eyes, others which were the offspring only of their own imaginations.
It is not easy to gather from the description what parts of the
exhibition were actually presented to the eyes of the spectators, and
what parts of it were imagined by themselves. It is quite evident
that the boy, as well as Agnolino Gaddi, were so overpowered with
terror that they fancied many things which they did not see; but when
the boy declares that four armed giants, of an enormous stature, were
threatening to break into the circle, he gives an accurate description
of the effect that would be produced by pushing the figures nearer the
mirror, and then magnifying their images, and causing them to advance
towards the circle. Although Cellini declares that he was trembling
with fear, yet it is quite evident that he was not entirely ignorant of
the machinery which was at work; for in order to encourage the boy, who
was almost dead with fear, he assured them that the devils were under
their power, and that “what he saw was smoke and shadow.”
Mr. Roscoe, from whose Life of Cellini the preceding description is
taken, draws a similar conclusion from the consolatory words addressed
to the boy, and states that they “confirm him in the belief, that the
whole of these appearances, like a phantasmagoria, were merely the
effects of a magic lantern produced on volumes of smoke from various
kinds of burning wood.” In drawing this conclusion, Mr. Roscoe has
not adverted to the fact, that this exhibition took place about the
middle of the 16th century, while the magic lantern was not invented
by Kircher till towards the middle of the 17th century; Cellini
having died in 1570, and Kircher having been born in 1601. There
is no doubt that the effects described could be produced by this
instrument, but we are not entitled to have recourse to any other
means of explanation but those which were known to exist at the time
of Cellini. If we suppose, however, that the necromancer either had a
regular magic lantern, or that he had fitted up his concave mirror in
a box containing the figures of his devils, and that this box with its
lights was carried home with the party, we can easily account for the
declaration of the boy, “that as they were going home to their houses
in the quarter of Banchi, _two of the demons whom we had seen at the
amphitheatre went on before us leaping and skipping, sometimes running
upon the roofs of the houses, and sometimes upon the ground_.”
The introduction of the magic lantern as an optical instrument
supplied the magicians of the 17th century with one of their most
valuable tools. The use of the concave mirror, which does not appear
to have been even put up into the form of an instrument, required a
separate apartment, or at least that degree of concealment which it
was difficult on ordinary occasions to command; but the magic lantern,
containing in a small compass its lamp, its lenses, and its sliding
figures, was peculiarly fitted for the itinerant conjuror, who had
neither the means of providing a less portable and more extensive
apparatus, nor the power of transporting and erecting it.
The magic lantern shown in the annexed figure consists of a dark
lantern, AB, containing a lamp G, and a concave metallic mirror, MN,
and it is so constructed that when the lamp is lighted not a ray of
light is able to escape from it. Into the side of the lantern is fitted
a double tube, CD, the outer half of which D is capable of moving
within the other half. A large plano-convex lens C, is fixed at the
inner end of the double tube, and a small convex lens D, at the outer
end; and to the fixed tube CE, there is joined a groove EF, in which
the sliders containing the painted objects are placed, and through
which they can be moved. Each slider contains a series of figures or
pictures painted on glass with highly transparent colours. The direct
light of the lamp G, and the light reflected from the mirror MN,
falling upon the illuminating lens C, is concentrated by it so as to
throw a brilliant light upon the painting on the slider, and as this
painting is in the conjugate focus of the convex lens D, a magnified
image of it will be formed on a white wall or white cloth placed at PQ.
If the lens D is brought nearer to EF, or to the picture, the distinct
image will be more magnified, and will be formed at a greater distance
from D, so that if there is any particular distance of the image which
is more convenient than another, or any particular size of the object
which we wish, it can be obtained by varying the distance of the lens
D from EF.
[Illustration: _Fig. 5._]
When the image is received on an opaque ground, as is commonly the
case, the spectators are placed in the same room with the lantern;
but, for the purposes of deception, it would be necessary to place
the lantern in another apartment like the mirror in Fig. 4, and to
throw the magnified pictures on a large plate of ground glass, or a
transparent gauze screen, stretched across an opening EF, Fig. 4, made
in the partition which separates the spectators from the exhibitor.
The images might, like those of the concave mirror, be received upon
wreaths of smoke. These images are of course always inverted in
reference to the position of the painted objects; but in order to
render them really erect, we have only to invert the sliders. The
representations of the magic lantern never fail to excite a high degree
of interest, even when exhibited with the ordinary apparatus; but
by using double sliders, and varying their movements, very striking
effects may be produced. A smith, for example, is made to hammer
upon his anvil,--a figure is thrown into the attitude of terror by
the introduction of a spectral apparition, and a tempest at sea is
imitated, by having the sea on one slider, and the ships on other
sliders, to which an undulatory motion is communicated.
The magic lantern is susceptible of great improvement in the painting
of the figures, and in the mechanism and combination of the sliders.
A painted figure, which appears well executed to the unassisted eye,
becomes a mere daub when magnified 50 or 100 times; and when we
consider what kind of artists are employed in their execution, we need
not wonder that this optical instrument has degenerated into a mere
toy for the amusement of the young. Unless for public exhibition,
the expense of exceedingly minute and spirited drawings could not be
afforded; but I have no doubt that if such drawings were executed, a
great part of the expense might be saved by engraving them on wood, and
transferring their outline to the glass sliders.
A series of curious representations might be effected, by inserting
glass plates containing suitable figures in a trough having two of its
sides parallel, and made of plate glass. The trough must be introduced
at EF, so that the figure on the glass is at the proper distance from
the object lens D. When the trough is filled with water, or with
any transparent fluid, the picture at PQ will be seen with the same
distinctness as if the figure had been introduced by itself into the
groove EF; but if any transparent fluid of a different density from
water is mixed with it, so as to combine with it quickly or slowly, the
appearance of the figure displayed at PQ will undergo singular changes.
If spirits of wine, or any ardent spirit, are mixed with the water, so
as to produce throughout its mass partial variations of density, the
figure at PQ, will be as it were broken down into a thousand parts,
and will recover its continuity and distinctness when the two fluids
have combined. If a fluid of less density than water is laid gently
upon the water, so as to mix with it gradually, and produce a regular
diminution of density downwards--or if saline substances, soluble in
water, are laid at the bottom of the trough, the density will diminish
upwards, and the figure will undergo the most curious elongations and
contractions. Analogous effects may be produced by the application of
heat to the surface or sides of the trough, so that we may effect at
the same time both an increase and a diminution in the density of the
water, in consequence of which the magnified images will undergo the
most remarkable transformations. It is not necessary to place the glass
plate which contains the figure within the trough. It may be placed in
front of it, and by thus creating as it were an atmosphere with local
variations of density, we may exhibit the phenomena of the mirage and
of looming, in which the inverted images of ships and other objects are
seen in the air, as described in another letter.
The power of the magic lantern has been greatly extended by placing
it on one side of the transparent screen of taffeta which receives
the images, while the spectators are placed on the other side, and
by making every part of the glass sliders opaque, excepting the part
which forms the figures. Hence all the figures appear luminous on a
black ground, and produce a much greater effect with the same degree of
illumination. An exhibition depending on these principles was brought
out by M. Philipstall in 1802, under the name of the _Phantasmagoria_,
and when it was shown in London and Edinburgh, it produced the most
impressive effects upon the spectators. The small theatre of exhibition
was lighted only by one hanging lamp, the flame of which was drawn up
into an opaque chimney or shade when the performance began. In this
“darkness visible” the curtain rose and displayed a cave with skeletons
and other terrific figures in relief upon its walls. The flickering
light was then drawn up beneath its shroud, and the spectators in total
darkness found themselves in the middle of thunder and lightning.
A thin transparent screen had, unknown to the spectators, been let
down after the disappearance of the light, and upon it the flashes of
lightning and all the subsequent appearances were represented. This
screen being half-way between the spectators and the cave which was
first shown, and being itself invisible, prevented the observers from
having any idea of the real distance of the figures, and gave them the
entire character of aërial pictures. The thunder and lightning were
followed by the figures of ghosts, skeletons, and known individuals,
whose eyes and mouth were made to move by the shifting of combined
sliders. After the first figure had been exhibited for a short time,
it began to grow less and less, as if removed to a great distance, and
at last vanished in a small cloud of light. Out of this same cloud the
germ of another figure began to appear, and gradually grew larger and
larger, and approached the spectators, till it attained its perfect
development. In this manner the head of Dr. Franklin was transformed
into a skull; figures which retired with the freshness of life came
back in the form of skeletons, and the retiring skeletons returned in
the drapery of flesh and blood.
The exhibition of these transmutations was followed by spectres,
skeletons, and terrific figures, which, instead of receding and
vanishing as before, suddenly advanced upon the spectators, becoming
larger as they approached them, and finally vanished by appearing to
sink into the ground. The effect of this part of the exhibition was
naturally the most impressive. The spectators were not only surprised
but agitated, and many of them were of opinion that they could have
touched the figures. M. Robertson, at Paris, introduced along with his
pictures the direct shadows of living objects, which imitated coarsely
the appearance of those objects in a dark night or in moonlight.
All these phenomena were produced by varying the distance of the magic
lantern AB, Fig 5, from the screen PQ, which remained fixed, and at the
same time keeping the image upon the screen distinct, by increasing
the distance of the lens D from the sliders in EF. When the lantern
approached to PQ, the circle of light PQ, or the section of the cone
of rays PDQ, gradually diminished, and resembled a small bright cloud,
when D was close to the screen. At this time a new figure was put
in, so that when the lantern receded from the screen, the old figure
seemed to have been transformed into the new one. Although the figure
was always at the same distance from the spectators, yet, owing to its
gradual diminution in size, it necessarily appeared to be retiring to
a distance. When the magic lantern was withdrawn from PQ, and the lens
D at the same time brought nearer to EF, the image in PQ gradually
increased in size, and therefore seemed in the same proportion to be
approaching the spectators.
Superior as this exhibition was to any representation that had been
previously made by the magic lantern, it still laboured under several
imperfections. The figures were poorly drawn, and in other respects not
well executed, and no attempt whatever was made to remove the optical
incongruity of the figures becoming more luminous when they retired
from the observer, and more obscure when they approached to him. The
variation of the distance of the lens D from the sliders in EF was not
exactly adapted to the motion of the lantern to and from the screen, so
that the outline of the figures was not equally distinct during their
variations of magnitude.
Dr. Thomas Young suggested the arrangement shown in Fig. 6 for
exhibiting the phantasmagoria.
[Illustration: _Fig. 6._]
The magic lantern is mounted on a small car H, which runs on wheels
WW. The direct light of the lamp G, and that reflected from the mirror
M, is condensed by the illuminating lenses CC, upon the transparent
figures in the opaque sliders at E, and the image of these figures is
formed at PQ, by the object lens D. When the car H is drawn back on
its wheels, the rod IK brings down the point K, and by means of the rod
KL, pushes the lens D nearer to the sliders in EF, and when the car
advances to PQ, the point K is raised, and the rod KL draws out the
lens D from the slider, so that the image is always in the conjugate
focus of D, and therefore distinctly painted on the screen. The rod KN
must be equal in length to IK, and the point I must be twice the focal
length of the lens D before the object, L being immediately under the
focus of the lens. In order to diminish the brightness of the image
when it grows small and appears remote, Dr. Young contrived that the
support of the lens D should suffer a screen S to fall and intercept a
part of the light. This method, however, has many disadvantages, and we
are satisfied, that the only way of producing a variation in the light
corresponding to the variation in the size of the image, is to use a
single illuminating lens C, and to cause it to approach EF, and throw
less light upon the figures when D is removed from EF, and to make C
recede from EF when D approaches to it. The lens C should therefore
be placed in a mean position, corresponding to a mean distance of the
screen, and to the ordinary size of the figures, and should have the
power of being removed from the slider EF, when a greater intensity of
light is required for the images when they are rendered gigantic, and
of being brought close to EF when the images are made small. The size
of the lens C ought of course to be such that the section of its cone
of rays at EF is equal to the size of the figure on the slider when C
is at its greatest distance from the slider.
The method recommended by Dr. Young for pulling out and pushing in
the object lens D, according as the lantern approaches to or recedes
from the screen, is very ingenious and effective. It is, however,
clumsy in itself, and the connexion of the levers with the screen,
and their interposition between it and the lantern, must interfere
with the operations of the exhibitor. It is, besides, suited only to
short distances between the screen and the lantern; for when that
distance is considerable, as it must sometimes require to be, the
levers KL, KI, KT, would bend by the least strain, and become unfitted
for their purpose. For these reasons the mechanism which adjusts the
lens D should be moved by the axle of the front wheels, the tube which
contains the lens should be kept at its greatest distance from EF by
a slender spring, and should be pressed to its proper distance by the
action of a spiral cam suited to the optical relation between the two
conjugate focal distances of the lens.
Superior as the representations of the phantasmagoria are to those of
the magic lantern, they are still liable to the defect which we have
mentioned, namely, the necessary imperfection of the minute transparent
figures when magnified. This defect cannot be remedied by employing
the most skilful artists. Even Michael Angelo would have failed in
executing a figure an inch long with transparent varnishes, when all
its imperfections were to be magnified. In order, therefore, to perfect
the art of representing phantasms, the objects must be living ones, and
in place of chalky ill-drawn figures, mimicking humanity by the most
absurd gesticulations, we shall have phantasms of the most perfect
delineation, clothed in real drapery, and displaying all the movements
of life. The apparatus by which such objects may be used, may be called
the _catadioptrical phantasmagoria_, as it operates both by reflexion
and refraction.
[Illustration: _Fig. 7._]
The combination of mirrors and lenses which seems best adapted for this
purpose is shown in Fig. 7, where AB is a living figure placed before
a large concave mirror MN, by means of which a diminished and inverted
image of it is formed at _ab_. If PQ is the transparent screen upon
which the image is to be shown to the spectators on the right hand of
it, a large lens LL must be so placed before the image _ab_, as to
form a distinct and erect picture of it at A´B´ upon the screen. When
the image A´B´ is required to be the exact size of AB, the lens LL
must magnify the small image _ab_ as much as the mirror MN diminishes
the figure AB. The living object AB, the mirror MN, and the lens LL,
must all be placed in a moveable car for the purpose of producing the
variations in the size of the phantasms, and the transformations of
one figure into another. The contrivance for adjusting the lens LL, to
give a distinct picture at different distances of the screen, will, of
course, be required in the present apparatus. In order to give full
effect to the phantasms, the living objects at AB will require to be
illuminated in the strongest manner, and should always be dressed
either in white or in very luminous colours; and, in order to give them
relief, a black cloth should be stretched at some distance behind them.
Many interesting effects might also be produced by introducing at AB
fine paintings and busts.
It would lead us into too wide a field were we to detail the immense
variety of resources which the science of optics furnishes for such
exhibitions. One of these, however, is too useful to be passed without
notice. If we interpose a prism with a small refracting angle between
the image _ab_, Fig. 7, and the lens LL, the part of the figure
immediately opposite to the prism will be as it were detached from
the figure, and will be exhibited separately on the screen PQ. Let us
suppose that this part is the head of the figure. It may be detached
vertically, or lifted from the body as if it were cut off, or it may
be detached downwards and placed on the breast as if the figure were
deformed. In detaching the head vertically or laterally, an opaque
screen must be applied to prevent any part of the head from being
seen by rays which do not pass through the prism; but this and other
practical details will soon occur to those who put the method to an
experimental trial. The application of the prism is shown in Fig. 8,
where _ab_ is the inverted image formed by a concave mirror, ABC a
prism with a small refracting angle BCA, placed between _ab_ and the
lens LL, _s_ a small opaque screen, and AB the figure with its head
detached. A hand may be made to grasp the hair of the head, and the
aspect of death may be given to it, as if it had been newly cut off.
Such a representation could be easily made, and the effect upon the
spectators would be quite overpowering. The lifeless head might then be
made to recover its vitality, and be safely replaced upon the figure.
If the head A of the living object AB, Fig. 7, is covered with black
cloth, the head of a person or of an animal placed above A might be set
upon the shoulders of the figure AB by the refraction of a prism.
[Illustration: _Fig. 8._]
When the figure _ab_, Fig. 8, is of very small dimensions, as in the
magic lantern, a small prism of glass would answer the purpose required
of it; but in public exhibitions, where the image _ab_ must be of a
considerable size, if formed by a concave mirror, a very large prism
would be necessary. This, however, though impracticable with solid
glass, may be easily obtained by means of two large pieces of plate
glass made into a prismatic vessel and filled with water. Two of the
glasses of a carriage window would make a prism capable of doubling
the whole of the bust of a living person placed as an object at AB,
Fig. 7, so that two perfectly similar phantasms might be exhibited. In
those cases where the images before the lens LL are small, they may
be doubled and even tripled by interposing a well-prepared plate of
calcareous spar, that is, crossed by a thin film. These images would
possess the singular character of being oppositely coloured, and of
changing their distances and their colours, by slight variations in the
positions of the plate.[8]
[8] See _Edin. Encyclopædia_, Art. OPTICS, Vol. xv., p. 611.
In order to render the images which are formed by the glass and
water prisms as perfect as possible, it would be easy to make them
achromatic, and the figures might be multiplied to any extent by using
several prisms, having their refracting edges parallel, for the purpose
of giving a similarity of position to all the images.
[Illustration: _Fig. 9._]
Among the instruments of natural magic which were in use at the revival
of science, there was one invented by Kircher for exhibiting the
mysterious hand-writing on the wall of an apartment, from which the
magician and his apparatus were excluded. The annexed figure represents
this apparatus as given by Schottus. The apartment in which the
spectators are placed is between LL and GH, and there is an open window
in the
side next LL, GH being the inside of the wall opposite to the window.
Upon the face of the plane speculum EF are written the words to be
introduced, and when a lens LL is placed at such a distance from the
speculum, and of such a focal length, that the letters and the place
of their representation are in its conjugate foci, a distinct image
of the writing will be exhibited on the wall at GH. The letters on
the speculum are of course inverted, as seen at EF, and when they are
illuminated by the sun’s rays S, as shown in the figure, a distinct
image, as Schottus assures us, may be formed at the distance of 500
feet. In this experiment, the speculum is by no means necessary. If the
letters are cut out of an opaque card, and illuminated by the light
of the sky in the day, or by a lamp during night, their delineation
on the wall would be equally distinct. In the daytime it would be
necessary to place the letters at one end of a tube or oblong box, and
the lens at the other end. As this deception is performed when the
spectators are unprepared for any such exhibition, the warning written
in luminous letters on the wall, or any word associated with the fate
of the individual observer, could not fail to produce a singular effect
upon his mind. The words might be magnified, diminished, multiplied,
coloured, and obliterated, in a cloud of light, from which they might
again reappear by the methods already described, as applicable to the
magic lantern.
The art of forming aërial representations was a great desideratum among
the opticians of the 17th century. Vitellio and others had made many
unsuccessful attempts to produce such images, and the speculations
of Lord Bacon on the subject are too curious to be withheld from the
reader.
“It would be well bolted out,” says he, “whether great refractions may
not be made upon reflexions, as well as upon direct beams. For example,
take an empty basin, put an angel or what you will into it; then go so
far from the basin till you cannot see the angel, because it is not in
a right line; then fill the basin with water, and you shall see it out
of its place, because of the refraction. To proceed, therefore, put a
looking-glass into a basin of water. I suppose you shall not see the
image in a right line or at equal angles, but wide. I know not whether
this experiment may not be extended, so as you might see the image and
not the glass, which, for beauty and strangeness, were a fine proof,
for then you should see the image like a spirit in the air. As, for
example, if there be a cistern or pool of water, you shall place over
against it the picture of the devil, or what you will, so as that you
do not see the water. Then put a looking-glass in the water; now if you
can see the devil’s picture aside, not seeing the water, it would look
like the devil indeed. They have an old tale in Oxford, that Friar
Bacon walked between two steeples, which was thought to be done by
glasses, when he walked upon the ground.”
[Illustration: _Fig. 10._]
Kircher also devoted himself to the production of such images, and he
has given in the annexed figure his method of producing them. At the
bottom of a polished cylindrical vessel AB, he placed a figure CD,
which we presume must have been highly illuminated from below, and
to the spectators who looked into the vessel in an oblique direction
there was exhibited an image placed vertically in the air as if it
were ascending at the mouth of the vessel. Kircher assures us that he
once exhibited in this manner a representation of the Ascension of our
Saviour, and that the images were so perfect that the spectators could
not be persuaded, till they had attempted to handle them, that they
were not real substances. Although Kircher does not mention it, yet
it is manifest that the original figure AB must have been a deformed
or anamorphous drawing, in order to give a reflected image of just
proportions. We doubt, indeed, if the representation or the figure was
ever exhibited. It is entirely incompatible with the laws of reflexion.
[Illustration: _Fig. 11._]
Among the ingenious and beautiful deceptions of the 17th century,
we must enumerate that of the re-formation of distorted pictures
by reflexion from cylindrical and conical mirrors. In these
representations, the original image from which a perfect picture
is produced is often so completely distorted, that the eye cannot
trace in it the resemblance to any regular figure, and the greatest
degree of wonder is of course excited, whether the original image is
concealed or exposed to view. These distorted pictures may be drawn
by strict geometrical rules; but I have shown in Fig. 11 a simple and
practical method of executing them. Let MN be an accurate cylinder made
of tin-plate or of thick pasteboard. Out of the farther side of it
cut a small aperture _abcd_; and out of the nearer side cut a larger
one ABCD, the size of the picture to be distorted. Having perforated
the outline of the picture with small holes, place it on the opening
ABCD, so that its surface may be cylindrical. Let a candle or a bright
luminous object, the smaller the better, be placed at S, as far behind
the picture ABCD as the eye is afterwards to be placed before it,
and the light passing through the small holes will represent on a
horizontal plane a distorted image of the picture A´B´C´D´, which,
when sketched in outline with a pencil, and shaded or coloured, will
be ready for use. If we now substitute a polished cylindrical mirror
of the same size in place of MN, then the distorted picture, when
laid horizontally at A´B´C´D´, will be restored to its original state
when seen by reflexion at ABCD in the polished mirror. It would be
an improvement on this method to place at ABCD a thin and flexible
plate of transparent mica, having drawn upon it with a sharp point,
or painted upon it, the figure required. The projected image of this
figure at A´B´C´D´ may then be accurately copied.
The effect of a cylindrical mirror is shown in Fig. 12, which is
copied from an old one which we have seen in use.
[Illustration: _Fig. 12._]
The method above described is equally applicable to concave cylindrical
mirrors, and to those of a conical form; and it may also be applied
to mirrors of variable curvature, which produce different kinds of
distortions from different parts of their surfaces.
[Illustration: _Fig. 13._]
By employing a mirror whose surface has a variable curvature like ABC,
Fig. 13, we obtain an instrument for producing an endless variety of
caricatures, all of which are characterised by their resemblance to
the original. If a figure MN is placed before such a mirror, it will
of course appear distorted and caricatured; but even if the figure
takes different distances and positions, the variations which the
image undergoes are neither sufficiently numerous nor remarkable to
afford much amusement. But if the figure MN is very near the mirror,
so that new distortions are produced by the different distances of
its different parts from the mirror, the most singular caricatures may
be exhibited. If the figure, for example, bends forwards his head and
the upper part of his body, they will swell in size, leaving his lower
extremities short and slender. If it draws back the upper part of the
body and advances the limbs, the opposite effect will take place. In
like manner different sides of the head, the right or the left side of
it, the brow or the chin, may be swelled and contracted at pleasure. By
stretching out the arms before the body they become like those of an
ourang-outang, and by drawing them back they dwindle into half their
regular size. All these effects, which depend chiefly on the agility
and skill of the performer, may be greatly increased by suitable
distortions in his own features and figure. The family likeness, which
is of course never lost in all the variety of figures which are thus
produced, adds greatly to the interest of the exhibition; and we have
seen individuals so annoyed at recognising their own likeness in the
hideous forms of humanity which were thus delineated, that they could
not be brought to contemplate them a second time. If the figure is
inanimate, like the small cast of a statue, the effect is very curious,
as the swelling and contracting of the parts and the sudden change
of expression give a sort of appearance of vitality to the image.
The inflexibility of such a figure, however, is unfavourable to its
transformation into caricatures.
Interesting as these metamorphoses are, they lose in the simplicity
of the experiment much of the wonder which they could not fail to
excite if exhibited on a great scale, where the performer is invisible,
and where it is practicable to give an aërial representation of the
caricatured figures. This may be done by means of the apparatus shown
in Fig. 7,[9] where we may suppose AB to be the reduced image seen in
the reflecting surface ABC, Fig. 13.[10] By bringing this image nearer
the mirror MM, Fig. 7, a magnified and inverted image of it may be
formed at _ab_, of such a magnitude as to give the last image in PQ the
same size as life. Owing to the loss of light by the two reflexions, a
very powerful illumination would be requisite for the original figure.
If such an exhibition were well got up, the effect of it would be very
striking.
[9] Page 86.
[10] Page 96.