Improvements in Kinematographic Apparatus.
Year: 1898

page_text: Date of Application (in United Kingdom), 28th Oct., 1898
Complete Specification Left, 19th Aug., 1899-Accepted, 28th Oct., 1899
PROVISIONAL SPECIFICATION.
Improvements in Kinematographic Apparatus.
PAUL MORTIER, Civil Engineer, of 7, Place Mi-Careme, St. Etienne, in the
Republic of France, do hereby declare the nature of this invention to be as
follows:-
All the apparatus hitherto constructed for reproducing animated scenes by
a series of views thrown on to a screen have two serious disadvantages.
Firstly: The pellicular bands or sensitised celluloid films, bearing the different
photographic pictures are drawn along by sudden jerks with intervals of repose.
Secondly: The illumination of the screen is effected with intervals of light.
and darkness, the periods of obscurity being utilised in substituting one plate
for another.
There is, in consequence, considerable vibration and wear of the parts of the
apparatus, as well as of the bands and an insupportable sensation of dazzling
in the eyes.
The object of this invention is to obviate these disadvantages.
"
Reduced to what is essential, this apparatus comprises a drum rotated in a
frame, by means of a horizontal shaft. The external cylindrical periphery of
the drum is in the form of a series of small windows, and, on this windowed
periphery, the printed pellicle is wound after the manner of a transmission belt."
on the rim of its pulley.
The apparatus is completed by a series of angular mirrors, the number
of which is equal to that of the windows. These mirrors are formed by the
junction of two sheets of glass, they are inclined at an angle of 90 degrees in
relation to one another, forming part with the body of the drum, or fixed thereto
in any suitable manner.
The whole apparatus represents thus a polygonal drum concentric to the "win-
dowed" drum and forming part therewith.
Every plate surrounded by a window of the drum, in virtue of the principle
of the angular mirrors, produces a virtual image rectangular parallel and inverted
in relation to the image that would be produced in a simple ordinary mirror,
and one of the symmetrical axes of which coincides exactly with the axis of rota-.
tion itself; so that whilst the plate, carried along in a circle by the drum, is

page_text: moving rapidly, its image, on the contrary is motionless on the axis. When the
term motionless is employed, it is not altogether exact; for, in reality, it is only
the symmetrical axis of the image, which corresponds with the axis of rotation,
that is motionless, the other portions of the image being subjected to a general
oscillating motion around this symmetrical motionless axis.
Nevertheless, when the angular amplitude of the motion is sufficiently feeble,
a few degrees for example, the image, in spite of its oscillating motion, may
be considered as motionless in relation to a point situated at a somewhat con-
siderable distance from this image and normal to its plane in its mean position.
This is why a projecting lens placed on this perpendicular will form on a
screen a true image, practically motionless and without deformation of the figure
which produces the virtual image.
If several successive plates, corresponding to several contiguous windows, are
illuminated at the same time by the condenser of the lantern, a certain number
of virtual images may exist simultaneously on the axis of rotation, and con-
sequently be thrown on to the picture sheet simultaneously. Thence it may be
conceived that the series of cliches constituting the same scene might be repro-
duced on the screen, not only without any discontinuity, or eclipse, but even
with the views co-existent one with the other. Such coexistence might result
in a confusion of lines and a general lack of clearness, but that is easily remedied,
by limiting the illuminated zone of the surface of the drum to a right-angle
corresponding to the dimension of a window, plus the separating bar between the
two windows. All the parts of the pellicle then pass successively through the
illuminated zone, and, there will appear on the screen two portions of two success-
sive views, which complete one another, without visible separation.
The virtual image is composed of the partial image of the upper illuminated
half of the plate and of the partial image of the lower illuminated half of the
plate. The two portions complete one another, and by means of the lens produce
on the screen a real complete image.
If the illuminating rays be rigorously confined by a suitable rectangular dia-
phragm, and the effective diameter of the lens allows of its receiving in every
case the rays issuing from the simultaneously illuminated parts of two adjoining
plates, no discontinuity, no variation of brightness and no scintillation can
possibly be perceptible in the projection.
"
It is thus necessary to regulate the admission of the light suitably, in order
that there may no longer be on the screen any portions more illuminated
which would produce a clearer line and any less illuminated parts which would
produce a darker line.
The same apparatus which, by means of the optic properties of a projecting
lens, enables real. images from successive plates to be reproduced on a screen,
also enables, by the action of the pupil of the eye, impressions to be produced
on the retina, which, in fact is a screen. The eye placed on the same normal.
line where we have just now supposed the objective to be placed, sees distinctly
and in its true size the virtual image of each plate. It can also see it enlarged
by the interposition of a magnifying lens.
It is obvious that if the apparatus be doubled, it may become stereoscopic and
give relief impressions.
The system involved in this apparatus may, on the principle of optic
reversibility, be employed for photographically recording any animated scene
whatever. The projecting lens thus becomes a photographic lens and a sensitive
band is substituted for the printed band. By the action of the same mirrors
which produced on the fixed screen true images practically motionless and without
deformation, the motionless points of the scene to be reproduced impress during a
certain time the same points of the sensitive band, the image accompanying the
band in its circular movement without any relative movement in relation to it.
There remains nothing but to separate the different pairs of mirrors by
blackened partitions, to place the whole in a dark chamber, proof against the

page_text: light, and to add thereto an obturator arrangement reducing the relative time
of pose for each plate and an excellent kinematographic recording apparatus will
be realised.
Dated this 28th day of August 1898.
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents,
I, PAUL MORTIER, Civil Engineer, of 7, Place Mi-Careme, St. Etienne, in the
Republic of France, do hereby declare the nature of this invention and in what
manner the same is to be performed to be particularly described and ascertained
in and by the following statement:—
All the apparatus hitherto constructed for recording and reproducing animated
scenes by a series of successive views, are based on one of the following prin-
ciples:
Firstly: The pellicular bands are drawn along by sudden jerks, with stopping
intervals, the periods of motion being utilised in substituting one plate for
another, and the stopping intervals for projecting the view or printing it. The
disadvantages attending this disconnected kind of action are known: immense
strain on the parts of the apparatus and on the bands, the eyes of the spectators
experiencing an insupportable sensation of dazzling, the screen presenting alter-
nately brilliant flashes of light, and absolute darkness.
Secondly: The bands, on the contrary, have a uniform and continuous motion;
but, in this case, it would not be possible to obtain a sharp impression of a fixed
picture on a rapidly-moving band, or a motionless projection of a moving plate,
without the employment of one or two of the following devices: mobility of the
objective, correlative to that of the band, or the introduction between the movable
plate and the object of a reflecting arrangement moving at a rate of speed corre-
sponding with that of the band itself. The first contrivance, which necessitates
a series of similar objectives as a focus or centre, is expensive and practically
impossible; the second has been employed with advantage in the toy known as
the praxinoscope, but it is not capable of producing actual kinematographs, unless
the special arrangements which form the object of the present application, be
employed.
The principle of the revolving mirrors reduced to its simplest form, and as
embodied in Reynauld's praxinoscope, is as follows:
A plane mirror and a drawing, the planes of which are parallel, revolve under
a rotary motion affecting the whole arrangement, around an axis, which is itself
parallel to these planes, and situated at a distance from the mirror exactly equal
to the distance between the mirror and the drawing.
According to the laws of reflection, the mirror should produce from the draw-
ing a symmetrical image of the drawing in relation to the mirror and therefore
situated in a plane formed parallel to the two others through the axis of rotation.
This virtual image of the drawing thus revolves at the same time as the whole
arrangement, which forms in some sense a single block.
If a certain number of mirrors forming a regular polygonal drum be brought
together around the axis, and a like number of drawings in the form of a circular
girdle or belt, a praxinoscope will be produced.
It appears that, in order to convert a praxinoscope into a kinematograph, it
would be sufficient to mount on the same axis a polygonal reflecting drum, and

page_text: a drum furnished with windows and teeth, on which an ordinary perforated
kinematographic band would be wound; if the diameter of the band cylinder.
were made double that of the circle described in the reflecting cylinder, and its
periphery equal to the combined lengths of as many plates as there are mirrors,
it would be possible to obtain an unlimited succession of practically motionless
images, which being thrown on to a fixed objective and reproduced on a screen,
would give the effect of kinematography. Unfortunately practice shows very
clearly that this assimilation is purely imaginary.
In the first place the luminous rays reflected by the mirrors cannot follow the
same path in returning as in going, which would cause them to pass through the
plate, and the illuminating lantern. Consequently the eye of the observer, or
the objective, cannot be placed in the axis perpendicular to the middle of the
virtual image. In other words, the image cannot be seen by the eye, or appear
on the objective, unless the observer be placed obliquely. This oblique vision
deprives the images of their theoretical immobility, as, in the slight turning on
the spot, the angles not only have alternate approaching and withdrawing move-
ments, not visible to the eye, or on the screen, but cross movements, which
produce very apparent transverse vibrations.
The second difficulty is due to its being impossible to have bands winding on
a toothed cylinder so as to completely cover it and with perfect engagement;
this would be, in fact, to assume in regard to the perforations an invariableness
and exactness impossible in practice with extensible and hygrometrical substances.
Strictly speaking, cylinders with adjustable diameters could be employed, but
it would be necessary at the same time to vary the diameter of the reflecting
cylinder, which must always be one half of the other. This disadvantage shows
itself in faintness, deformations, and longitudinal vibrations of the pictures,
due to the bands being bulged, not in focus, and not at the distance from the
mirrors requisite for their fixity.
The third difficulty lies in the nature of the reflecting mirrors themselves.
If, for instance, we take mirrors superficially coated with silver, the silver coat-
ing soon changes to such an extent that the mirrors lose all their brilliancy. If,
on the contrary, mirrors with silver lining under the glass are employed, the
images are double, and wanting in sharpness.
The arrangements by means of which these numerous obstacles are overcome
and a kinematographic apparatus produced which is simpler and more perfect
than the best in use are hereinafter fully described.
The principle of the apparatus will first be described, and then certain details
of construction be dealt with.
In the accompanying drawing Fig. 1 is an elevation of a kinematographic
apparatus constructed according to this invention. Fig. 1 is a plan of the
same. Fig. 2 is a vertical sectional elevation of the reflecting drum. Figs. 2
and 3 are views of a mirror and projecting lens showing the manner of projecting
the pictures. Fig. 4 is a side elevation of the drum and reflecting mirror; Fig. 5
is an end elevation of the same, showing the method of mounting the drum and
picture carriers. Figs. 6, 7, and 8 are diagrammatic representations showing
correct and incorrect projections.
Figs. 9 and 10 are end and side views respectively of reflecting prisms, and
Fig. 11 is a sectional elevation at right angles of an attachment for ensuring
the proper travel of the pellicle or photographic band.
A drum C is supported on a horizontal shaft a--y mounted to rotate in a
frame Z¹. Around this drum C the printed pellicle or band is carried after the
manner of a transmission belt on the rim of its pulley, a number of holes in the
edge of the band engaging in points or teeth S₁ formed on the drum.
A series of angular mirrors S each formed by the junction of two sheets of
glass inclined at an angle of 90 degrees, in relation to each other, are arranged
in a circle, forming part with the drum C, or attached thereto in any suitable
manner.

page_text: The whole thus forms a polygonal drum concentric to the drum C, and forming
part therewith, each angular mirror comprising two reflecting faces perpendicular
to the plane of Fig. 2, which is a diametrical section passing through the centre
of the axis of rotation, y. The intersection of the reflecting faces is a straight
line normally passing through the plane of the figure at a point A situated in
the middle of the radius Oh, Fig. 2.
In these conditions every plate of the band wound on the drum C will, in
accordance with the principle of the prisms with total reflection, produce a
virtual image rectangular parallel and inverted in relation to the image that
would be produced on a single ordinary mirror and one of the symmetrical axes
of which exactly coincides with the axis of rotation itself, so that, whilst the
plate carried along by the drum C moves rapidly, its image on the contrary is
practically motionless on the axis e, y. In reality, it is only the symmetrical
axis of the image, which corresponds with the axis of rotation, that is motionless,
the other portions of the image being subjected to a general oscillating motion
around this symmetrical motionless axis.
Nevertheless, when the angular amplitude of the rotary motion is sufficiently
feeble a few degrees for example--the image, in spite of its oscillating motion,
may be. considered as motionless in relation to the eye that will be placed at
a considerable distance from this image and on the perpendicular carried through
the centre of this image normally to its plane in its mean position.
Thus it may be assumed that a projecting lens, placed on this perpendicular,
will form on a screen a true image practically motionless and without deformation
of the figure which produces the virtual image.
If several successive plates be illuminated at the same time by the condensor
of the lantern, a certain number of virtual images may exist simultaneously on
the axis of rotation, and consequently be thrown on to the picture sheet simul-
taneously. Thence it may be conceived that the series of plates constituting the
same might be reproduced on the screen, not only without any discontinuity or
eclipse, but even with the views co-existent one with the other. Such co-existence
might result in a confusion of lines and a general lack of clearness, but this is
casily remedied by limiting the illuminated surface of the drum to a right angle
corresponding to the dimensions of one view of the band.
Thus all the parts of the pellicle pass through the illuminated zone successively,
and there appear on the screen first two portions of two successive views, com-
plementary each of the other, without any visible separation, Fig. 2", then a
single complete view, Fig. 3.
The virtual image ao b is composed of the partial image a¹ o of the illu-
minated upper half of the plate A' ' and of tre partial image ob of the
illuminated lower half of the plate A B. The two portions are complementary
of each other and produce through the objective a complete and real image Fig. 8,
on the screen X, Fig. 1ª.
If the diaphragm be too small, a black band is seen, (Fig. 6), if it be too large
a band of double light," Fig. 7.
In these conditions, if the illuminated rays be rigorously confined by a suitable
rectangular diaphragın, and the effective diameter of the objective allows of its
receiving in every case the rays issuing from the simultaneously illuminated
parts of two adjoining plates, no discontinuity, no variation of brightness, and
no scintillation can possibly be perceptible in the projections.
It is thus necessary to regulate the admission of the light suitably, in order
that there may no longer be on the screen any portions more illuminated
which would produce a clearer line and any less illuminated parts which would
produce a darker line.
It is also necessary to have an exact adjustment of the views in relation to
the successive plates.
It remains to be explained why the angular mirror is required-a single mirror
would, in fact, form the desired motionless image, but the objective capable of

page_text: projecting the image, could not be facing this image except it were precisely
in the return path of the luminous incident rays, a thing which it is impossible
to realise; hence the use of two angular mirrors which reflect the image parallel
to the incident rays, as shown in Figs. 1 and 2.
In Fig. 4 will be seen the windows and the angular mirrors S S, and in Figs. 1
and 5 the drums or cylinders T and T for the winding and unwinding of the
pellicle R, as well as the frame Z and the frame Z¹.
On the frame Z is placed the objective Z2 which produces the luminous pro-
jection, the direction of which is altered by the interposition of a reflector X¹.
By means of a crank fitting to one or other of the shafts of T or T', motion is
imparted to the pellicle in either direction.
The same apparatus which, by means of the optic properties of a projecting
lens, enables real images from successive plates to be reproduced on a screen,
also enables by the action of the pupil of the eye, impressions to be produced
on the retina which, in fact, is a screen. The eye placed on the same normal
line where we have just now supposed the objective to be placed, sees distinctly
and in its true size the virtual image of each plate. It can also see it enlarged
by the interposition of a magnifying glass.
It is obvious that if the apparatus be doubled, it may become stereoscopic and
give relief impressions.
Finally the system involved in this apparatus may, on the principle of optic
reversibility, be employed for photographically recording any animated scene
whatever. The projecting lens thus becomes a photographic lens, and a sensitive
band is substituted for the printed band. By the action of the same mirrors
which produced on the fixed screen true images practically motionless and without
deformation, the motionless points of the scene to be reproduced impress during a
certain time the same points of the sensitive band, the image accompanying the
band in its circular movement without any relative movement in relation to it.
There remains nothing but to separate the different pairs of mirrors by
blackened partitions, to place the whole in a dark chamber, proof against the
light, and to add thereto an obturator arrangement reducing the relative time
of pose for each plate and an excellent kinematographic recording apparatus will
be realised.
The above statement shows the principle of my invention, and the description
of one process of its application. I have already indicated the disadvantages
arising in relation to firstly, the oblique view or vision; secondly, the employ-
ment of reflecting silver plated mirrors; thirdly, the practically perfect winding
of the bands on the drum C.
The employment of reflecting silvered mirrors presents very considerable
practical difficulty unless exceedingly thin sheets of silvered glass be used, which
do not produce any confusion by double reflection. The use of these glasses
belongs to the principle of my invention.
In order to obviate the first and second disadvantages referred to, I have made
use of the total reflection prism known as Porro's prism for the front view or
face vision instead of the silvered mirrors--see Figs. 1º, and 10.
It will be seen that the luminous projection enters the prism at 1 and is
reflected from the face 2 to face 3 and emerges at 4. The method of assembling
the prisms to form a continuous reflecting ring or cylinder is shown in Fig. 10.
The triangular faces of each prism are suitably inclined to each other towards the
apex 5 to facilitate the cylindrical formation of the reflecting cylinder. This
invariable prism replaces the system of mirrors inclined at 90 degrees, and has
all its advantages without any of its defects.
In order to secure perfect laying on of the band it is necessary to alter the
principle of the praxinoscope considerably, by causing the band to rotate around
the axis, not with an angular rate of speed equal to that of the reflecting drum
itself, as in Reynauld's system, but at a less rate of speed. In these conditions
a reflecting drum situated mid-way of the axis in relation to the mirrors would

page_text: not produce, it is admitted, a virtual immoveable image, but theory easily proves
that a series of mirrors placed within this half or mid-distance at a certain fixed
point, produced the required motionlessness; the difference of angular speed
has its effect exactly nullified by the voluntary error of symmetry.
This principle is realised in very simple fashion--in Fig. 11-the band is
wound on a toothed drum which forms part with the reflecting drum S engaging
with and lying on it with more or less exactitude, which is without importance
thereafter; it is then detached to pass into a flat or arched frame P outside the
drum C pivotted at X3 and adjusted by means of a set screw L working in a
slot. The plates, in passing from the frame, have the same circumferential
velocity as the circle of engagement, and consequently the frame being at a
greater distance from the axis, an angular velocity less than the angular velocity
common to the toothed drum C and to the reflecting drum S formed by the collec-
tion of Porro's prisms.
In order to arrive at a practical arrangement, and to render the images motion-
less, it is necessary that the half of the radius of the circle of engagement should
be smaller than the radius of the circle described in the polygon of the mirrors
and equal to the distance from the frame to the mirrors.
By mirror polygon is understood, that formed by the ordinary flat mirrors or
by the meeting edges of angular mirrors.
It follows from this that the circle of engagement may vary according to the
track of the perforation, without affecting the immoveable character of the
images provided that the position of the frame varies in consequence. This is
a simple question of adjustment.
It will be understood that the band held tight in a frame, will be always per-
fectly flat and exactly in focus.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is: —
1. In kinematographic apparatus; traversing the pellicle or photographic film
in front of reflectors that produce a virtual image thereof, rectangular, parallel,
and inverted in relation to the image that would be produced on a single plane
mirror, rotating the reflectors about an axis lying in the plane of the virtual
image, and coincident with the symmetrical axis thereof, and projecting the
image onto a screen by means of a lens substantially as described.
2. In kinematographic apparatus the combination with a drum on which the
photographic band or film is traversed, of a frame which regulates the angular
rate of speed of the film.
3. The improved kinematographic apparatus, substantially as described with
reference to the drawings.
Dated this 28th day of July 1899.
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents.