the brim of the neck of a bottle (Fig. 100). The forks and the cork
form a whole, of which the centre of gravity is fixed over the point
of support. You can tip the bottle, empty it even, if it contains
fluid, without the little construction over its mouth being in the
least disturbed from its balance. The vertical line of the centre of
gravity passes through the point of support, and the forks oscillate
with the cork, which serves as their support, thus forming a movable
structure, but much more stable than one is inclined to suppose.
This curious experiment is often performed by conjurors, who inform
their audience that they will undertake to empty the bottle without
disturbing the cork. (_b_) If a woodcock has been served for dinner,
or any other bird with a long beak, take off the head at the extreme
end of the neck; then split a cork so that you can insert into it
the neck of the bird, which must be tightly clipped to keep it in
place; two forks are then fixed into the cork, exactly as in the
preceding example, and into the bottom of the cork a pin is inserted.
This little contrivance is next placed on a piece of money, which
has been put on the opening of the neck of the bottle, and when it
is fairly balanced, give it a rotatory movement, by pushing one of
the forks as rapidly as you please, but as much as possible without
any jerk. You will then see the two forks, and the cork surmounted
by the woodcock’s head, turning on the slender pivot of a pin.
Nothing can be more comical than to witness the long beak of the
bird turning round and round, successively facing all the company
assembled round the table, sometimes with a little oscillation, which
gives it an almost lifelike appearance. (_c_) Lifting a glass bottle
full of water by means of a simple wisp of straw. The straw is bent
before being passed into the bottle of water, so that, when it is
lifted, the centre of gravity is displaced, and brought directly
under the point of suspension. It is well to have at hand several
pieces of straw perfectly intact and free from cracks, in case the
experiment does not succeed with the first attempt. (_d_) The next
experiment, though apparently very difficult, will be found easy
enough in practice if the hand be steady. Take a key, and by means
of a crooked nail, or “holdfast,” attach it to a bar of wood by a
string tied tightly round the bar. To the other extremity of the bar
attach a weight, and then drive a large-headed nail into the table.
It will be found that the key will balance and even move upon the
head of the nail, without falling. The weight is under the table, and
the centre of gravity is exactly beneath the point of suspension.
Inertia.--(_e_) Take a broomstick, and place it horizontally, passing
the ends through two paper rings. Then ask two children to hold the
paper rings by means of two razors, so that the rings rest on the
blades. This done, take a stout stick, and, with all your strength,
strike the broomstick in the centre; it will be broken into shivers,
but the paper rings will not be torn in the least, or even cut by
the razors! (_f_) A modification of _e_. A needle is fixed at each
end of the broomstick, and these needles are made to rest on two
glasses, placed on chairs; the needles alone must be in contact with
the glasses. If the broomstick is then struck violently with another
stout stick, the former will be broken, but the glasses will remain
intact. The experiment answers all the better the more energetic the
action. (_g_) A wooden ball is suspended from the ceiling by a rather
slender thread, and a similar thread is attached to the lower end
of the ball. If the lower thread is pulled forcibly it will break
with the force of the pull; the movement communicated to it has not
time to pass into the ball; if, on the contrary, it is pulled very
gradually, and without any shock, the upper thread instead will
break, because in this case it supports the weight of the ball.
Motion is not imparted simultaneously to all parts of a body, but
only to the particles first exposed to a blow, for instance. One
might multiply examples of this. If a bullet be shot from a gun,
it will make a round hole in a piece of wood or glass, whilst if
thrown by the hand--that is to say, with much less force--it will
shiver the wood or the pane of glass to pieces. When the celerity of
the motive force is very great, the particles directly affected are
disturbed so quickly that they separate from the adjacent particles
before there is time for the movement to be communicated to the
latter. (_h_) It is possible, for the same reason, to extract from
a pile of money a piece placed in the middle of the pile without
overturning the others. It suffices to move them forcibly and
quickly with a flat wooden ruler. The experiment succeeds very well
also if performed with draughtsmen piled up on the draught-board.
(_i_) Take a strip of paper, and upon it place a coin, on a marble
chimney-piece. If, holding the paper in the left hand, you strike
it rapidly and forcibly, you will be enabled to draw away the paper
without causing the coin (say a five-shilling piece) to fall down.
(_j_) It is not impossible to draw away a napkin laid as a tablecloth
for one person’s dinner, without disturbing the various articles
laid upon it. A quick motion is all that is necessary, keeping the
napkin tightly extended by the hands at the same time. This latter
experiment, however, is not recommended to boys home for the holidays.
Pressure of Air.--(_k_) The force of air can be shown as acting with
considerable pressure upon an egg in a glass. By blowing in a claret
glass containing a hard-boiled egg, it is possible to cause the egg
to jump out of the glass; and with practice and strength of lungs it
is not impossible to make it pass from one glass to another. (_l_)
The force of heated air ascending can also be ascertained by cutting
up a card into a spiral, and holding it above the flame of a lamp.
The spiral, if lightly poised, will turn round rapidly. (_m_) A
wine glass, a plate, and water will serve for the next experiment.
Pour some water on the plate, light a piece of paper resting on a
cork, and cover the flame with the glass, which turn upside down.
The water rises in the glass. Why?--Because the burning of the paper
having absorbed a part of the oxygen, and the volume of confined
gas being diminished, the pressure of the outer air has driven back
the fluid. Next fill a goblet with water up to the brim, and cover
it with a sheet of paper, which touches both the edge of the glass
and the surface of the water. Turn the glass upside down, and the
sheet of paper prevents the water running out, because it is held
in place by atmospheric pressure. It sometimes happens that this
experiment does not succeed till after a few attempts on the part
of the operator; thus it is prudent to turn the glass over a basin,
so that, in case of failure, the water is not spilt. (_n_) Having
obtained a vase and a bottle, both quite full of water, take the
bottle, holding it round the neck so that the thumb can be used as a
stopper, then turn it upside down, and pass the neck into the water
in the vase. Remove your thumb, or stopper, keeping the bottle in a
vertical position, and you will see that the water it contains does
not escape, but remains in suspension. It is atmospheric pressure
which produces this phenomenon. If, instead of water, we put milk
in the bottle, or some other fluid denser than water, we shall see
that the milk also remains suspended in the bottle. (_o_) Light a
piece of paper, and let it burn, plunging it into a water-bottle
full of air. When the paper has been burning a few seconds close the
opening of the water-bottle by means of a hard-boiled egg, which you
have previously divested of its shell, so that it forms a hermetic
stopper. The burning of the paper has now caused a vacuum of air in
the bottle, and the egg is gradually thrust in by the atmospheric
pressure outside. (_p_) Take a thin piece of wood about ⅛ in. thick,
8 in. wide, and 24 in. long, and lay it upon a table so that it shall
project over the edge. It is evident that the least pressure will
make it tilt and fall. Next spread out a large newspaper over the
end that lies upon the table. Now if you strike a sharp blow with
your fist on the projecting portion, you will be much surprised to
see that the board resists the shock, just as if it were nailed to
the table. If you strike hard you may injure your hand, or perhaps
the board will break into pieces, but you will not lift the simple
paper that holds it. The downward pressure of the atmosphere upon a
wide surface explains the phenomenon. In order that the experiment
may succeed well, the paper should be spread flat and evenly upon the
table, and all the folds should be smoothed out so as to expel the
interposed air.
Equilibrium of Floating Bodies.--(_q_) The equilibrium of bodies
floating upon liquids is an occurrence of daily observation, but such
is not the case as regards aeriform fluids--a soap bubble filled
with air and floating upon a stratum of carbonic acid, for example.
Although this pretty experiment would seem to require complicated
apparatus to carry it out, it may nevertheless be performed very
simply, as follows:--Having procured a glass vessel, such as a
bell-glass, of medium size, place it, mouth upward, upon a tripod
made of coarse wire, or upon any other support. In the bottom of
this vessel place a mixture formed of equal parts soda bicarbonate
and tartaric acid reduced to powder. The quantity of powder to be
employed depends upon the size of the vessel and the thickness
of the stratum of carbonic acid that it is desired to have. Soda
bicarbonate contains carbonic acid to the amount of half its weight,
and consequently it is necessary to decompose 4 grammes (66 gr.)
of bicarbonate to produce 1 litre (61 cub. in.) of carbonic acid
gas. Over the mouth of the glass vessel place a disc of cardboard
of sufficient size to cover it exactly, and, in the centre of this,
make a circular aperture to allow of the passage of a glass rod of
sufficient length to rest upon the bottom and project externally.
Through this tube, and by means of a small funnel, water is
introduced in small quantities at a time (so as not to produce too
lively an effervescence) until the powder is entirely covered. When
the carbonic acid ceases to be given off, the tube is taken out.
Care should be taken to prepare beforehand a solution of soap in
water, or, what is better, some of Plateau’s glyceric liquid. With
either of these liquids, bubbles about 4 in. in diameter are blown
at the extremity of a tube that flares slightly. This tube should
be held vertically while carrying the bubble over the cardboard
cover, and the latter should be carefully removed by sliding it off
horizontally, and the bubble be then detached in such a way that it
shall fall in the direction of the vessel’s axis. If the fall occurs
from a certain height, the ball will rebound as if it were repelled
by a spring. It will then descend and rise again, and finally become
immovable. It is at this moment that it is well to replace the cover,
so that no disturbance shall occur in the interior of the vessel.
The bubble then resembles a small balloon in equilibrium in the
atmosphere of the vessel; but, in reality, it is floating upon the
invisible stratum of carbonic acid. This equilibrium, however, is
of short duration, since the carbonic acid rapidly dissolves in the
liquid envelope of the bubble, and passes into the interior of the
latter, and increases its weight to such a degree as to cause it to
gradually descend to the bottom of the vessel, where it disappears.
But a suspension of several balls may be obtained successively, that
is to say, the experiment may be repeated several times, if, on
removing the cover, care be taken not to disturb the atmosphere of
the vessel.
The soap bubble may be replaced by one of those small rubber balloons
that please children so much, and that weigh, on an average, 1 gramme
each. Upon inflating one of these to a diameter of about 6 in., we
shall obtain an equilibrium that has greater fixedness and duration,
and may observe the phenomenon at our leisure.
Chemical Experiments.--It is well known that the vapours of mercury
are very diffusive in their nature, and some quite singular
experiments have been devised based upon this, and upon the fact that
the salts of silver and the chlorides of gold, platinum, iridium, and
palladium are affected by these mercurial vapours. If any one, for
instance, write upon a sheet of white paper with platinum chloride,
no mark would be visible, as the liquid is quite colourless. If,
however, the same sheet of paper be held over a little mercury, the
metal will be brought out on the paper in dark tints. This magical
apparition of a figure or drawing on a sheet of paper which appears
to be perfectly white is very astonishing to the spectator.
On the other hand, reversing the experiment, a no less marvellous
result is obtained. At first expose the drawing in writing to the
gases of mercury; the lines will become charged with mercury, and
then by simply bringing the drawing in contact with a sheet of paper
previously sensitised with a solution of platinum, the drawing will
be reproduced, line for line, on the white paper. Drawings made in
this way give a charming effect, the tones being very soft and the
lines being distinct and clear.
_Optical Delusions._--Those talking decapitated persons that are
so often seen in various kinds of shows are one of the sights that
always prove successful. They have already astonished a number of
generations past, and will probably prove just as attractive to those
that shall succeed our own. These decapitated persons are seen under
different aspects according to the tricks employed to produce the
illusion, and which all have the same aim in view, that is, to cause
the appearance, on a table or tray, of a living head with no visible
body. This illusion may be produced in several ways. (_a_) At the
Foire aux Pains d’Epices of 1880, one of the side shows exhibited a
decapitated person as follows: The small stage, which was draped with
a black fabric covered with silver spangles, was feebly lighted by
a sort of night lamp attached to the ceiling. To the right and left
were seen panoplies of skulls and cross-bones. The spectators were
in darkness. In the middle of this grim place a tray was suspended
by 3 small chains at about 3 ft. from the floor, and upon this tray
there was a living head--that of a young man who an instant before
had shown himself to the public. His body lay extended out under the
tray, and his head talked, drank, and smoked, while his arms and legs
moved. Both, although quite distinct, were perfectly alive.
The trick by which the illusion was obtained consisted in this: The
body belonging to the apparently decapitated head was hidden behind,
under the tray, and was completely invisible owing to the shadow of
the latter, and the partial darkness of the stage. The apparent body
was that of another person of exactly the same height, size, and
dress, whose head was in the dark and further hidden by black cloth.
(_b_) Recently there was exhibited at Paris, in what is called the
“Théâtre des Merveilles,” another example of a decapitated person.
A young girl first appears before the audience, accompanied by an
executioner clad in red and armed with the traditional axe. Then
the curtain drops, but rises in a few moments, and shows the stage
a little darkened. Near the executioner, however, can be perfectly
distinguished the girl’s head lying on a round table at the back of
the stage; her body is seen lying on a bed at a few feet from her
head, and at her side is the fatal block that has served for the
execution. The effect is dramatic. The trick employed is the same
as the preceding, in that it requires two persons of the same size
wearing the same costume. One of these--the one who showed herself to
the public--makes the head, her body being hidden behind the cloth in
the rear of the stage. The other, who makes the body, has her head
bent far back and hidden in a sort of box, a false cardboard neck
contributing to increase the illusion.
(_c_) Upon entering the room we perceive a black wooden square table
having 4 legs. Over one of its angles there is thrown a piece of
red fabric whose other end may be perfectly seen hanging from the
opposite side. The floor, which is strewn with straw, is continuous
to the back of the stage. There is nothing under the table,
then--there can be no doubt of it. Still, upon this table there lies
on a tray the head of a young girl which smiles and answers questions
that are asked it. The ingenuous spectators are almost persuaded that
the girl has no body; others ask themselves where it is hidden; and
very peculiar suppositions are indulged in on all sides. In a word,
the illusion is perfect.
When, through favour or money, we enter the side scene and look at
the table sideways, we are almost ashamed of having allowed ourselves
to be deceived by so simple a trick; for the apparatus consists, in
fact, only of a mirror fixed obliquely to two legs of the table. This
mirror hides the body of the girl, who is on her knees or seated on a
small stool, and reflects the straw which covers the floor so as to
make it appear continuous under the table, and likewise reflects the
front leg of the table so as to make it appear at an equal distance
from the other side and thus produce the illusion of a fourth leg.
It also reflects the end of the red fabric hanging in front of the
table, and thus makes it appear to hang down also from behind. It
should be remarked that during the exhibition the spectator stands
only a few inches away from the table and head, being separated
therefrom by a wooden railing from which hangs a curtain reaching
to the ground. Such proximity of the spectator and actor would
seem to favour a discovery of the trick; but, on the contrary, it
is indispensable to its success. Were the spectator placed at a
distance, and did the curtain not exist, he might by stooping see his
legs reflected in the mirror. The curtain, then, prevents any one
from looking under the railing, and the rays that might reach him
from the curtain, by being reflected in the glass, are lost beneath
the table, owing to the proximity of the latter.
As may be seen, the trick is easily understood, and, moreover, it
is one of those that gives the best results, since it deceives the
public the best. Besides, it has the merit of great age.
(_d_) The living half-woman is a very ingenious improvement on the
decapitated individual. On entering, we perceive, when the curtain is
drawn aside, an elegant little room decorated with flowers and lights
and hung with curtains and tapestry. In front there are two railings,
and the floor is covered with a carpet. In the centre is seen a small
square table, on which rests a sort of three-legged stool supporting
a cushion and the half body. The latter is the body of a young woman
apparently cut in two just beneath the thighs. Naturally, this young
person shows that she is alive by moving her arms and head, and
speaking and singing. Now, as we can see the 4 legs of the table and
can perfectly distinguish the space under the stool, and that too
in full light, we naturally ask by what means the lower part of the
girl’s body is hidden. On raising the stool, it will be seen that it
is formed only of a hollowed-out disc whose supports are connected
by two mirrors, that make with each other an angle of 45°. These
mirrors rest on the top of the table, which is decorated with regular
designs in mosaic, and reflect the latter in such a way that they
seem to continue uninterruptedly under the stool. The table presents
an analogous arrangement, two legs being connected with the foremost
one by two mirrors (the table is placed cornerwise to the audience).
These mirrors reflect not only the designs of the carpet, which by
their continuity produce the illusion of a vacancy, but also 2 table
legs located on each side behind the railings. The mirror to the left
transmits to the spectators on that side the image of the leg placed
on the left, and this image seems to them to be the fourth leg of the
table. The mirror to the right plays the same rôle with regard to the
spectators on that side. These mirrors, in addition, hide the lower
portion of the girl’s body.
(_e_) The Dircksian phantasmagoria, which was more generally known
as “Pepper’s Ghost,” is another example of the illusive effects of
mirrors suitably arranged. On a moderate scale the same spectral
apparitions can be produced as an entertainment for the drawing-room.
Dircks arranged an oblong chamber in two equal portions, making the
separation by means of one vertical screen of thin glass having a
perfectly true surface. Suppose each chamber to measure 12 ft. square
and 12 ft. high. Let one of these be the stage on which the acting
is to take place; its floor and three of its walls are solid, and
the fourth or front of it is one entire glass screen; the ceiling
must be made to open at different parts to let in light, and have
suitable blinds to regulate the light and shade in which the actors
perform. The chamber opposite, or facing the actors, is in reality
a second stage for carrying out the spectral performances, and is
differently constructed; the two sides may be large folding or
sliding doors, or may be left quite open, or one side closed and the
other open; but the ceiling must cover only that half of the top away
from the glass screen or partition, thus leaving an open space in the
ceiling of 6 ft. by 12 ft.; through this space so left in the ceiling
the spectators obtain a full view of the stage, their seats being
above the half ceiling described, and thrown rather backwards than
forwards; the line of vision thus being at an angle of about 45° with
respect to the vertical glass screen, or plane unsilvered crystal
mirror. It will now be obvious that the actor on the stage beneath
the seats of the spectators can only be seen by reflection, and the
trained actor on the opposite stage, knowing the precise situations
of the reflection as seen by the spectators, performs accordingly, so
that, when really seeming to stand confronting the vision, the actor,
whose reflection is thus seen as a vision, is as far from the screen
on one side as his reflection is cast on the other.
Some striking effects may be produced illustrative of the illusive
properties of optical apparatus constructed on the principle
described. Thus, _a figure placed before a white screen_ is so
strongly reflected, that the spectator cannot divest his mind of
their being the substance and not the shadow which he observes,
particularly as he contrasts them with an adjacent solid figure. By
placing _two figures of corresponding form_ equidistant, one on each
side of the glass mirror or screen, they appear as one, until one is
moved; and if they differ in colour, as one blue and one white, the
effect seems more remarkable. If _a cabinet_, _box_, _or the like_,
is placed, one on each side of the mirror, until the image of one
exactly corresponds with the material figure of the other, then the
spectator may see the visionary figure open a drawer or door, and
remove and replace anything therein, and afterwards the solid figure
repeat the same acts. If the reflection of an actor is thrown on a
transparent screen it is invisible, but by gradually decreasing the
light the spectral appearance will be as gradually developed until
apparently it becomes a firm solid figure in all its proper costume,
and acting in perfect conformity to its designed character.
[Illustration: 101. 102. The Dircksian Phantasmagoria.]
[Illustration: 103. 104. The Dircksian Phantasmagoria.]
The arrangement of the apparatus will be understood by reference to
Figs. 101-104, in which--
Fig. 101 is an external perspective view, Fig. 102 a vertical
section, Fig. 103 a top, or bird’s-eye view, and Fig. 104 a plan.
A, B, C, D, E is a box, closed on all sides, but provided at D with
a door F, and on the other side with another door G, both hinged to
the back A, D. H, I, J are flapped openings on the top of the box;
K, K a partition dividing the interior of the box, made of a good,
clear, and even surface of thin patent plate-glass, kept in its place
within two side grooves; L, M, two separate chambers or compartments
produced by K, K, the transparent mirror; N, a ceiling or screen
over the compartment L, to exclude any object therein from the direct
view of the spectator, as shown by the dotted line, _a, b_.
If two figures be now introduced, one Y, the other Z, and the eye of
the spectator be fixed at A, he will observe two images, one the real
figure Z, the other Y’, the mere reflection of Y. By this arrangement
it is evident that the plain, unsilvered glass, thus viewed at an
angle of about 45° has all the properties of a mirror, but owing
to its transparency two figures are seen, possessing little or no
distinguishable difference between them. Of course a person placed at
Z sees only the figure Y, but, as a piece of acting may, under proper
arrangements of a suitable stage, approach the situation apparently
occupied by Y’, and thus indicate to a spectator placed at A any
pre-arranged dramatic scene requiring Z to be in correspondence with
the visionary figure Y’.
In using the apparatus the flap H must be open, but I may be shut,
being mostly useful to get admission for inserting or withdrawing the
screen or the figures; the flap J may be closed or opened to regulate
the admission or exclusion of light. The doors F, G may both be wide
open, though one is generally sufficient, provided it is turned as
direct as possible to the light. A mirror placed at an angle close
to the opening F or G, will assist the illusion by illuminating the
figure Y, thus heightening the effect of the reflection Y’.
If two geometrically proportionate figures, as spheres, cubes, or the
like, be placed in the situations Y, Y’, then the image at Y’ will be
a vision and a substance combined, as will at once appear by slightly
moving the substantial body in either compartment L or M. Let the
duplicate figure be a box, and then the spectator might observe the
apparent anomaly of the same box being opened and a substance taken
from it and replaced either by a substantial or visionary actor. When
the compartment M is lighted up no vision appears, but the light
being made gradually to fade and disappear, the vision would seem
lifelike, as at first. As it is evident that the right hand of the
vision is the left hand of the actor in the compartment L, all his
acts requiring the right would have to be performed with the left
hand, to appear natural to the spectator. It is also requisite for
insuring a good effect, that no solid figure in the compartment M
shall come before or behind the visionary image, as its transparency
would at once become evident; but if anything of the kind is desired,
then the background, figure, or object, should be placed behind the
actor Y, and become with him also visionary; in this way _a white
screen_ placed behind the actor Y will allow his shadow to appear
on it and give great force and solidity to his reflected figure or
vision at Y’.
A few examples will better illustrate than any elaborate description,
the singular effects that may, in different ways, be adopted for
realising spectral dramas.
1.--DICKENS’S HAUNTED MAN.
A student is seen sitting at a table spread over with books, papers,
and instruments. After a while he rises and _walks about_ the
chamber. In this there is nothing remarkable. But the audience is
perplexed by a different circumstance: they not only see a man rise
from his seat and see him walking about, but they also see that _he
still sits immovably in his chair_--so that evidently there are two
persons instead of one, for, although alike in dress, stature, and
person, their actions are different. They cross and recross; they
alternately take the same seat; while one reads the other is perhaps
walking; and yet they appear very sullen and sulky, for they take no
notice of each other, until one, after pushing down a pile of books,
passes off by walking through the furniture and walls.
The art in this arrangement is to have two actors sufficiently alike
in person, similarly dressed, and placed so that the phantom figure
sits so exactly like the living figure as to match into it. It
consists in having two actors, two chairs, and two tables exactly
matching each other. On the acting stage, the actor, table, and chair
have each their duplicate; so that, if they were pulled a little to
one side, the audience would see two actors, two tables, and two
chairs. But such an exhibition would be a defect, as the table and
chair are mere guides for the spectre actor: if there were no chair
he could not sit, and if no table he could not appear as leaning upon
one, or seem to do so.
In this and other pieces of a like nature, it is presumed that the
parts are not performed in dumb show, but that an able speaker either
explains and gives the dialogue, or that concealed actors address the
audience, timing their speech to the action before them.
2.--THE RETURNED MARINER.
A naval officer or other seafaring character, belonging to some
particular vessel reported to have been wrecked, is seen in a
chamber, into which his wife or sister, &c., on entering rushes
forward to embrace him, but, clasping nothing, immediately falls down
in a swoon.
3.--THE CALIFORNIAN GAMBLERS, OR ROBBERS.