AN IMPROVED APPARATUS FOR THE PRODUCTION OF OPTICAL ILLUSIONS CALLED THE PRAXINOSCOPE.
Year: 1877

page_text: LETTERS PATENT to Charles Emile Reynaud, of Paris, in the French Republic,
for the Invention of "AN IMPROVED APPARATUS FOR THE PRODUCTION OF
OPTICAL ILLUSIONS CALLED THE PRAXINOSCOPE.'
"
PROVISIONAL SPECIFICATION left by the said Charles Emile Reynaud at the
Office of the Commissioners of Patents on the 13th November 1877.
CHARLES EMILE REYNAUD, of Paris, in the French Republic. "AN IMPROVED
APPARATUS FOR THE PRODUCTION OF OPTICAL ILLUSIONS CALLED THE PRAX-
INOSCOPE.'
333
The object of this Invention is to produce the illusion of motion by means of
Drawings representing the successive phases of an action. The same end was
attained by the instrument known as the " phenakisticope;" but my Invention
differs therefrom both in principle and in apparatus, and is altogether new.
The principle of my Invention is. based on the laws of reflection in plane mirrors,
and is as follows:-If, as illustrated in the accompanying diagram, a plane mirror
A, B, be placed at a certain distance from a drawing C, D, the picture will be vir-
tually seen as at C³, D¹. Let the drawing be moved round the point o (and let the
mirror follow the same movement) until their positions are respectively D, F, and
B, E, the reflected picture will be seen as at C, D, its axis O not having changed
its position.
Now let another mirror and drawing be placed in the positions A, B, and C, D,
and imagine the eye to be at M; then half of the first drawing will be seen at
O, D, and half of the second at O, C. If the rotation is continued we shall soon
have mirror No. 2 at T, T', and drawing No. 2 at S, S', and then the picture No. 2
will be seen whole as at C, D¹¹. The mirror No. 2 and its drawing will proceed
to B, E, and D, F. Then supposing another mirror No. 3, and drawing at A, B, and
C, D, the same phenomena will occur in succession.

page_text: From this theory it will be evident that if a series of drawings be placed round
the perimeter of a regular polygon of any number of sides, and turn together round
the centre thereof, they will be seen successively as at that centre, if plane mirrors
be placed on a concentric polygon of one half the diameter of the first, and turned
by the same motion.
This well-known optical illusion will cause the drawings to appear as if they
belonged to one picture, and thus it will be easy to produce the illusion of animation
by representing on these drawings the successive phases of any given action.
The eye will receive no other disagreeable impression than a very slight alter-
nating of angles from C¹, D¹, to C, D, around the central axis of the one reflected
picture; the degree of the angle will be in proportion evidently to the number of
sides of the polygon, and consequently the more sides there are to the polygon the
less pronounced will be the angle.
The essential parts of the instrument invented by me in accordance with this
principle are,
Firstly. A regular prism, the sides of which are plane reflecting surfaces (or
mirrors). This prism is suitably arranged to turn on its axis.
Secondly. A series of drawings equal in number to the sides of the prism, and
placed at exactly double the distance of the mirrors from the common centre.
In practice I shall call the reflecting, prism the "mirror carrier," and the polygon
will be made in a circle and will be described as the "circlet."
"
The "mirror carrier" is placed on a pivot fixed to a suitable support or pedestal,
and rests on a flat plate, to which it is fixed firmly or not, as may be most conve-
nient. At or near the edge of this plate is arranged the circlet" which carries
the drawings, which may be changed at will; the "circlet" is double the diameter
of the "mirror carrier." The instrument may be set in motion either by hand or
by a suitable mechanical arrangement such as clockwork or electricity.
Such are the essential parts of my Invention, and they may be applied in nume-
rous ways, a few of which are as follows:-
1. A moveable screen may be so arranged as to hide all the side figures and leave a
only the central animated picture exposed to view.
2. Two "mirror carriers" and two "circlets" may be arranged to obtain by
means of a stereoscope the double illusion of relief and animation.
3. Amirror carrier" may be combined with a "circlet" of transparent pictures,
provided with a lens or lenses, and illuminated by any suitable and strong light to 3
obtain an enlarged projection of animated pictures on a screen.
4. A central support for a lamp or candle may be placed above the "mirror
carrier" to light up this instrument.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Charles Emile Reynaud in the Great Seal Patent Office on the
6th May 1878.
CHARLES EMILE REYNAUD, of Paris, in the French Republic. "AN IMPROVED
APPARATUS FOR THE PRODUCTION OF OPTICAL ILLUSIONS CALLED THE PRAXI-
NOSCOPE."
The object of this Invention is to produce the illusion of motion by means of
drawings or illustrations representing the successive phases of an action. This
object has already been attained by an instrument known as and called the
phenakisticope;" but the principle and construction of my apparatus are different
from those of that apparatus, they are entirely new, and in them my Invention
consists.
The principle being founded on a law of reflection of plane mirrors it is necessary
to give first a short technical description thereof :-If, as in Figure 1 on the acconi-
panying Sheet of Drawings, a plane mirror A, B, be placed at a certain distance from
a picture C, D, the reflection of the picture will be seen at C¹, D¹. Now let both
the picture and the mirror revolve on the centre .O at equal speeds, and let their new
positions be B, E, and D, F, the reflection will then be seen at C, D; the axis O
will not have been displaced.
If another picture and another mirror be placed in the former positions A, B, and
C, D, the eye being at M, then one half of the first picture will be seen at O, D¹¹,
and one half of the second picture will be seen at O, C¹.
If the rotation is now
continued the mirror No. 2 will soon arrive at T, T¹, and the picture No. 2 at S, S¹,
then the whole of the reflection No. 2 will be seen at C, D The mirror No. 2
and its picture will then move on to B, E, and D, F, and supposing then another.
mirror and picture No. 3 to be at A, B, and C, D, the same succession of phenomena
will take place.
The result of this principle is that a series of pictures placed on a regular polygon
of any number of sides, and revolving round the centre of this polygon, are seen
successively at that centre, if plane mirrors are placed on a concentric polygon, the
sides of which are at half the distance of those of the first polygon to the common
centre, and which revolves at the common speed.
The well-known optical illusion will cause these pictures to appear as if they'
belonged to one and the same illustration, and thus it will be casy to produce
the illusion of "animation" by representing on the pictures the successive phases of
any action.
The eye will have no disagreeable impression except that of a slight intermittent.
alteration of angles round the axis of the centre reflection (from C', D', to C¹¹, D");,
and this alteration will correspond with the number of the sides of the polygon,
and the more sides there are to the polygon the more imperceptible will this altera-
tion be.
The application of the above-mentioned principle designed by me to produce 'the
instrument which is the object of this Patent consists―
Firstly. Of a regular prism, the sides of which are plane mirrors or other plane
reflecting surfaces so arranged as to revolve round its own axis.
Secondly. Of a series of illustrations of any description, and equal in number to
the sides of the prism, or more or less numerous, according to the effect to be pro-
duced, but so placed as to revolve together with the reflecting prism, and at a
distance exactly double that of the mirrors themselves from the common centre of
rotation.
In its practical form I call the reflecting prism the "mirror carrier," and the
polygon of drawings will be made cylindrical and will be called the "circlet."
The mirror carrier A, B, as seen at Figure 2, is placed on a pivot which is fixed

page_text: on a stand or support, it rests on a disc C, D, on which it is fixed either permanently
or so as to be removed and replaced at will. On the edge of this disc rests in the
same manner the "circlet" E, F, G, which carries the pictures; these latter are movable
and can be changed at pleasure. The diameter of the "circlet" is double that of the
mirror carrier; the instrument is set in motion either by hand, clockwork, elec-
tricity, or by other motive power.
Such is the essential form of the instrument, which I shall make in various sizes;
but any other arrangement which shall be an application of the same principle is
necessarily a modification of my Invention.
My apparatus or instrument is further capable of the following modifications:-
Firstly. The disposition of a movable screen which will keep the side representa-
tions out of sight, and only display to view the central animated picture as in
Figure 3.
Secondly. The combination of two "mirror carriers" and two "circlets" to obtain
(by regarding the same through a stereoscope) the illusion of relief at the same time
as that of motion, as in Figure 4.
Thirdly. The combination of a "mirror carrier," of a "circlet" of transparent pictures
illuminated by a suitable strong light, and of one or more lenses to obtain the pro-
jection of animated pictures on an enlarged scale (see Figure 5).
Fourthly. The adaptation of a central support above the mirror carrier to permit
of lighting up by lamp or candle this apparatus, which may be placed on a drawing-
room table (see Figure 6).
All these modifications are either completed or in course of execution, and the
accompanying Drawings and letters of reference explain clearly the nature of my
Invention.
Figure 1 has already been fully explained in the description.
In Figure 2 P is the support or stand of the apparatus; O is the axis or pivot on
which the instrument revolves; C, D, is the disc which carries the "circlet" and the
"mirror carrier," and which revolves on the pivot O; E, F, G is the "circlet" which
rests on the edge of the disc, and inside which are placed the pictures representing
the successive phases of an action; A, B, is the "mirror carrier" or prism, of which O
is the centre and O, A, its radius, equal to half the radius of the "circlet." The
number of mirrors or sides is the same as the number of divisions on the "circlet."
G, G, G, are the mirrors composing the carrier. The central animated figure is
seen at I.
In Figure 3, A, B, C, D, E, F, is the screen, shewn also detached beneath. It is
placed inside the "circlet" at a very slight distance therefrom, but without touching
it anywhere. It is attached to the centre or pivot (which should be fixed) by wires
A, B, C, D, or otherwise, so that the screen is immovable, whilst the disc, the mirror
carrier, and the circlet, all revolve. One or more openings at M, M³, N, N¹, allow the
observer to see with ease the central animated picture I.
Figure 4. In this arrangement the instrument, or the two combined instruments,
revolve on a horizontal axis. A, B, C, D, are two "mirror carriers" (or rather the one
is a prolongation of the other). E, F, G, H, is a double "circlet," which carries two
series of stereoscopic pictures. The central animated pictures are seen at I and II, and
they are necessarily stereoscopic also, and if an ordinary stereoscope be placed before
I, I, the illusions of relief and animation will both become apparent at the same
time.
In Figure 5 the instrument is furnished with transparent pictures, the "circlet'
being open. Two sources of brilliant light (oxyhydrogen, as in the Drawing, or other-
wise) project convergent rays by means of a lens L, L', (the other is indicated
behind). These rays pass through the transparent pictures and are reflected by the
mirrors on to one object glass O, O¹, which projects them in the ordinary way on to
a screen placed at a suitable distance therefrom. The rotation of the apparatus does
not interrupt the projection, as the rays come first from one source of light and then
from another on to the object glass.

page_text: In Figure 6 a lamp or candle is placed on the fixed axis or pivot. A shade or
reflector lights up the pictures and keeps the light from the eyes. The reflection is
seen at I.
Having now described the nature and object of my said Invention, together with
the manner in which the same is to be or may be performed or carried into prac-
tical effect, I would remark in conclusion that I claim as my Invention, the con-
struction and use of a revolving reflecting prism or plane mirror carrier in combina-
tion with an outer circlet of designs, having double its radius revolving therewith
also, and representing the successive phases of an action so as to produce by reflection
the appearance of movement, the same being arranged and constructed substantially
as herein-before described and illustrated by the annexed Drawings..
In witness whereof, I, the said Charles Emile Reynaud, have hereunto set
my hand and seal, this Fifth day of April, in the year of our Lord
One thousand eight hundred and seventy-eight.
5
Witness,
M. G. MENNONS,
52, Rue Basse du Rempart,
Paris.
CHARLES EMILE REYNAUD. (L.S.)