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The Equipment Department
OF
Motion Picture
News
to supplement the information
contained in this book.
Data on Theatre Planning, con-
struction and equipment supplied
without charge.
Read the Equipment Department
to get the latest facts about
new devices, inventions and
"short cuts."
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MOTION PICTURE
PROJECTION
ISAAC GOLDMANN COMPANY
NEW YORK CITY
.^S^SSt* 2 O
MOTION PICTURE
PROJECTION
An Elementary Text-Book
I
BY JAMES R. CAMERON
Technical Editor
Exhibitors' Trade Review
International Cinema Review
Educational Film Magazine
SECOND EDITION
1921
Published by
THE THEATRE SUPPLY Co.
124 West 45th Street
New York City
MOTION PICTURE " PROJECTION
GLOSSARY OF ELECTRICAL AND
MECHANICAL TERMS
ACETATE. A salt formed by the action of acetic acid upon
a base.
ACTUAL HORSE POWER. The exact useful power given
out by an engine: found by subtracting the power used by
the machine itself from the indicated horse power.
ACHROMATIC LENSES. The color effect caused by the
chromatic aberration of a simple lens greatly impairs its
usefulness. This may be overcome by combining into one
lens a concave lens of flint glass and a convex lens of crown
glass.
ALIGN. To place or form in line.
ALLOY. A mixture of two or more metals.
ALTERNATING CURRENT. A current that changes its
flow of directign so many .times a second according to the
construction of the alternator. Written A. C.
AMMETER. An instrument used to measure the flow of
amperes.
AMPERE. The unit of current strength.
AMPERE HOUR. The quantity of electricity passed by a
current of one ampere in one hour.
One ampere flowing for one hour.
Two amperes flowing for one-half hour.
One-half ampere flowing for two hours: all equal one ampere
hour.
ANCHOR BOLTS. Bolts used for fastening machines to their
foundation.
ANTI-FRICTION METAL. A tin-lead alloy like Babbitt
metal.
APERTURE. An opening of any description in a partition.
ARC. The arc between two carbon electrodes slightly sepa-
rated.
ARC RECTIFIER. An apparatus used to change A. C. to
D. C.
ARMATURE. A collection of pieces of iron designed to be
acted on by a magnet.
ASBESTOS. A fibrous variety of ferro-magnesium silicate;
is a non-conductor of heat and fireproof.
ASBESTOS COVERED WIRE. A cable containing very
fine strands of copper wire all twisted together and covered
with an asbestos covering. Used wherever heat is generated.
MOTION PICTURE PROJECTION
On motion picture circuits used between the table switch and
arc lamp.
AUTOMATIC. Self acting.
AUTOMATIC SHUTTER. The shutter covering the film
aperture in gate of machine and controlled by the centrifugal
or governor movement, is so arranged that the shutter will
remain up so long as the machine is in motion, but should
the machine stop for any reason then the shutter falls and
cuts off the rays of light from the film in gate. (A fire pre-
vention device.)
AUTO TRANSFORMER. A transformer provided with only
one coil instead of two. Part of the coil being traversed by
the primary circuit and part being traversed by the sec-
ondary circuit.
B. & S. W. G. Abbreviation for Brown & Sharpe. Wire
Gauge.
B. W. G. Abbreviation for Birmingham Wire Gauge.
B. X. Metal tubing containing two conductors, each conductor
insulated from the other by a rubber covering, and both
wires wrapped with a composition covering so as to com-
pletely fill the tubing.
BABBITT METAL. An anti-friction metal.
BACK FOCUS. Properly called working distance.
BACK FOCAL LENGTH OF LENS. The distance from the
back of the lens to the film in the gate, while the film image
is in focus on the screen.
BALANCE WHEEL. A fly wheel. A wheel added to ma-
chinery for the purpose of preventing too sudden variations
in speed.
BALL & SOCKET JOINT. A joint in which a spherical
object is placed within a socket made to fit it.
BALL BEARING. A bearing whose journal works upon a
number of metal balls. Used to reduce friction to a mini-
mum.
BED PIECE. The frame carrying the dynamo or motor.
BORE. The interior diameter of a cylinder.
BRUSH. A rod of carbon held in a holder and pressed
against the commutator.
BUSINESS. Action by the player; e. g., business of shutting
door.
BUST. A small, magnified part of a large scene.
CABLE. An insulated electric conductor.
CAM FRICTION. The friction existing between the cam and
the member connected to it.
CAMERA. An expression used to command the photographer
to begin taking the scene.
MOTION PICTURE PROJECTION
CANADA BALSAM. A gum obtained from the Balsam Fir
of Canada. Used for cementing lenses.
CARBON. One of the elements, exists in three forms, char-
coal, graphite and diamond. It is used as electric conductor
for arc lamps and incandescent lamp filaments. The car-
bons used for arc lamps generally have a central core of
soft carbon.
CARRYING CAPACITY. The capacity of an electrical con-
ductor to carry current without overheating.
CENTIMETER. Unit of length, 0.3937 inch.
CENTRIFUGAL FORCE. The force which draws a body
constrained to move in a circular path, away from the center
of rotation.
CHANGE OVER. The stopping of one projecting machine
and the simultaneous starting of a second machine in order
to maintain an uninterrupted picture on the screen when
showing a multiple-reel story.
CHECK NUT, generally called lock-nut. A nut placed over
another nut on same bolt to lock the main nut in place.
CHROMATIC. Relating to color.
CHROMATIC ABERRATION. When white light is passed
through a spherical lens, both refraction and dispersion (the
decomposition of white light into several kinds of light)
occur. This causes a separation of the white light into the
various colors and causes images to have colored edges. This
effect which is most observable in condenser lenses is due
to the unequal refrangibility of the simple colors.
CINE. A prefix used in description of the motion-picture art
or apparatus.
CIRCUIT. The path through which the electric current flows.
CIRCUIT BREAKER. Any apparatus for opening or clos-
ing a circuit.
CIRCUIT-CLOSED. A circuit closed so as to give the cur-
rent a continuous path.
CIRCUIT, OPEN. A circuit with its continuity broken, as by
the opening of a switch.
CLOSE-UP. Scene or action taken with the character close
to the camera.
COLLODION. A solution of pyroxylin (soluble gun cotton)
in ether. Used in film cement.
COMMUTATOR. That part of a dynamo that changes the
direction of the currents.
10 MOTION PICTURE PROJECTION
COOLING PLATE. The plate around the film aperture on
gate which protects the gate itself from getting overheated
from the rays of light from arc lamp.
CONDUCTOR. Anything that will permit the passage of
electricity. A wire.
CONDENSERS. A lens or set of lenses used to gather the
rays of light from the arc lamp and bring them to a fixed
point of focus on aperture in gate.
The lens combination which deflects the diverging rays of
the luminant into the objective.
Collector Lens. The lens next to the source of light.
Converging Lens. The lens nearest the objective.
Middle Lens. Of a three-lens combination, the lens lying
between the collector lens and the converging lens.
CONDUIT. A metal pipe through which electrical conductors
are run.
CONTACT, ELECTRIC. A contact between two conductors
giving a continuous path for the current.
CONSTANT LOAD. A load whose pressure is steady and in-
variable.
CONTINUOUS. Uninterrupted without break, or interrup-
tion.
CONVERTER. An electric machine or apparatus for chang-
ing the potential difference of an electrical circuit.
CORROSION. Chemical action which causes destruction of a
metal, usually by oxidation or rusting.
CORRUGATED. Formed with a surface consisting of alter-
nate valleys and ridges.
COULOMB. The practical unit of quantity of electricity. It
is the quantity passed by a current of one ampere intensity
in one second.
CRATER. The depression that forms in the positive carbon
of a voltaic arc.
CURRENT FREQUENCY. The number of times alternating
current changes its flow of direction a second. The changes
are called cycles.
CUT-BACK. Scenes which are returns to previous action.
CUT-IN. Anything inserted in a scene which breaks its con-
tinuity.
CUTTING. Editing a picture by elimination of useless or
unacceptable film.
DEVELOPING. Making visible the latent image in an ex-
posed film.
DIRECT CURRENT. A current that flows in the one direc-
tion- Written D. C.
MOTION PICTURE PROJECTION 11
DIMMER. An adjustable choking coil used to regulate the
intensity of electric incandescent lamps.
DIRECTOR. The person who directs the actual production
of the photoplay.
DISSOLVE. The gradual transition of one scene into another.
DOUBLE EXPOSURE. The exposure of a negative film in
a camera twice before development.
DOUBLE PRINTING. The exposure of a sensitive film
under two negatives prior to development.
DOUSER. The manually operated door in the projecting
machine which intercepts the light before it reaches the film.
DUPE. A negative made from a positive.
DUPLEX. Double; working in two ways at once.
DYNAMOS. A machine driven by power used to convert me-
chanical energy into electrical energy.
E. M. F. Abbreviation for electric-motive force.
ECONOMIZER. A step-down transformer.
EFFECTIVE APERTURE. The largest diameter of a lens
available under the conditions considered.
ELECTRICITY. An unknown power; a powerful physical
agent which manifests itself mainly by attraction and repul-
sions, also by luminous and heating effects, by violent com-
motions, by chemical decompositions and many other phe-
nomena.
ELECTRODE. The terminal of an open electric circuit.
EQUIVALENT FOCUS. The distance from a point half way
between the back and front combination of lenses to the
film in the gate while picture is in focus on screen.
Can be obtained by measuring the distance between the
front and back combination then dividing by two and adding
the result to the back focal length. (Written E. F.)
The equivalent focus of a plurality of lenses in combina-
tion is the focal length of a simple thin lens which will under
all conditions form an image having the same magnification
as will the given lens combination.
EXHAUST FAN. An air propeller used to create a vacuum.
EXTERIOR. A scene supposed to be taken out of doors.
FADE-IN. The gradual appearance of the picture from dark-
ness to full screen brilliancy.
FADE-OUT. The gradual disappearance of the screen-
picture into blackness. (The reverse of fade-in.)
FEATURE. A pictured story, a plurality of reels in length.
FIRE TRAP. An arrangement of rollers on the upper and
lower magazines through which the film is fed, used to pre-
vent the flame, in case of fire, from entering the magazines.
FIXING. Making permanent the developed image in a film.
12 MOTION PICTURE PROJECTION
FLAT. A bit of painted canvas, or the like.
FLASH. A short scene, usually not more than three to five
feet of film.
FLASH-BACK. A very short cut-back.
FOCAL. Pertaining or belonging to a focus.
FOCUS. The point of concentration. When rays reflected
from all points meet or concur.
FOOTAGE. Film length measured in feet.
FLICKER SHUTTER. A revolving shutter on head of ma-
chine just in front of the projection lens, its use being to
cut off the rays of light from screen while the film is in mo-
tion in gate.
FRAME (verb). To bring a frame into register with the
aperture during the period of rest.
FRAME (noun). A single picture of the series on a motion-
picture film.
FRAME LINE. The dividing line between two frames.
FRAMING DEVICE. An attachment on the machine which
allows the operator to frame the picture on screen.
FUSE. A short length of wire of a given fusable point in-
troduced into the electrical circuit.
FUSING POINT. The temperature at which metals melt and
become liquid.
GENERATOR. An apparatus for maintaining an electrical
current.
GOVERNOR MOVEMENT. The movement that works the
automatic shutter, works by centrifugal force.
GRAPHITE. A soft form of carbon, used as a lubricant.
GROUND. The contact of an electrical conductor with the
earth, or with some other conductor not in the circuit.
HORSE POWER. A unit of rate of work. Equal to the rais-
ing of 33,000 pounds, one foot in one minute; equal to 746
watts.
INDUCTION. The property of a charged body on A. C. to
charge a neighboring body running parallel to it without any
tangible form of connection.
INDUCTOR. A step-down transformer.
IMPEDANCE. Is to an A. C. circuit what resistance is to a
D. C. circuit.
INSULATING TAPE. A prepared tape to cover the ends
of bared wire.
INTERMITTENT MOVEMENT. The movement that drives
the intermittent sprocket, generally a four-to-one movement.
INTERMITTENT SPROCKET- The sprocket which engages
the film to give it intermittent movement at the picture
aperture.
MOTION PICTURE PROJECTION 13
INSERT. Any photographic matter, without action, in the
film.
INTERIOR. Any scene supposed to be taken inside a build-
ing.
IRIS. An adjustable lens diaphragm.
IRISING. Gradually narrowing the field of vision by a me-
chanical device on the camera.
JOINING. Splicing into a continuous strip (usually 1,000
feet) the separate scenes, titles, etc., of a picture.
KILOWATT. Equal to 1,000 watts.
LAMINATED. Made up of a number of thin sheets.
LANTERN PICTURE. A still picture projected on a screen
by means of an optical lantern or stereopticon.
LANTERN SLIDE (see slide). The transparent picture
from which a lantern picture is projected.
LEADERS. That piece of blank film attached to the begin-
ning of the picture series.
LENS. A lens may be defined as a piece of glass or other
transparent substance with one or both sides curved. Both
sides may be curved, or one curved and other flat.
The object of the lens is to change the direction of rays
of light and thus magnify objects or otherwise modify vision.
Lenses may be classed as:
Double convex Double concave
Piano convex Piano concave
Concavo convex Convexo concave
The focus of a lens is the point where the refracted rays
meet.
LIGHT BEAM. A bundle of light rays.
LIGHT RAY. A thin line of light.
LOCATION. Any place selected for the action of an outdoor
scene.
LOST MOTION. Motion in a part of machine that produces
no useful results.
LUBRICANT. An oil used to diminish friction in the work-
ing parts of machinery.
LUG. A wire terminal.
MAGAZINE VALVE. The film opening in the magazine of
a motion-picture projector.
MAN POWER. Equal to one-tenth of a horse power.
MASKS. Opaque plates of various sizes and shapes used in
the camera to protect parts of the negative from exposure.
MICA. A mineral more or less transparent and used for in-
sulating.
MIL. Unit of length.
MIL, CIRCULAR. Unit of area.
14 MOTION PICTURE PROJECTION
MOTION-PICTURE. The synthesis of a series of related
picture elements, usually of an object in motion.
MOTION-PICTURE FILM. The ribbon upon which the
series of related picture elements is recorded.
MOTION-PICTURE PROJECTOR. An optical lantern
equipped with mechanisms for suitably moving motion-picture
film across the projected light.
MOTOR GENERATOR. A motor connected to a generator.
MOTOR REGULATOR. An adjustable rheostat used to reg-
ulate the speed of the motor.
MOVIES. Motion pictures.
MULTIPLE. Multiple connection is when each lamp draws
its supply direct from the main and is not depending on any
other lamp or set of lamps for supply.
MULTIPLE-REEL. A photoplay of more than a thousand
feet of film in length.
NEGATIVE. The opposite to positive; the pole to which the
current is supposed to flow.
NEGATIVE. The developed film, after being exposed in a
camera.
NEGATIVE STOCK. Light sensitive film intended for
motion-picture camera use.
NON CONDUCTOR. Any material that does not conduct
electricity.
OBJECTIVE. The picture-forming member (lens) of the
optical system. The objective lens of a moving picture
machine generally consists of four lenses, two in the front
combination and two in the rear. The two lenses in the
front are cemented together with Canada Balsam and called
the compound lens. The back combination consists of two
lenses separated by a metal ring, called the duplex lens.
The convex or greatest convex side of a lens always faces
the screen.
OHM. The unit of electrical resistance.
OSCILLATION. A moving backward and forward; swinging
like a pendulum.
OPTIENCE. A collection of persons assembled to see
motion pictures.
PAM. Contraction for panorama.
PANORAM. The act of, or device for, turning a motion-
picture camera horizontally, to photograph a moving object,
or to embrace a wide angle of view.
PHOTOPLAY. A story in motion pictures.
POLARITY. Pertaining to the two opposite poles of a cir-
cuit; the positive and negative.
POLYPHASE. More than one phase, multiphase.
MOTION PICTURE PROJECTION 15
POSITIVE. The developed film, after being printed through
a negative.
POSITIVE STOCK. The light-sensitive film intended to be
printed upon through a negative.
PRE-RELEASE. A picture not yet released for public
showing.
PRESSURE, ELECTRIC. Electric motive force, voltage.
PRIMARY COIL. The coil of a transformer, connected to the
source of electrical supply.
PRIMARY COLORS. Red, yellow, blue.
PRIMARY POWERS. Water power, wind power, tide power,
power of combustion, power of vital action.
PRINT. Same as "positive."
PRODUCER. The maker of photoplays.
PROGRAM. The complete show for a single optience.
PROJECTION DISTANCE. The distance between the screen
and the objective of a stereopticon lantern or motion-
picture projecting machine.
PROJECTING LENS. Properly called projection objective.
PROJECTION OBJECTIVE. The objective which forms an
image of the lantern slide or film, upon the screen.
PROPS. Contraction of properties. Objects used as acces-
sories in a play.
RACING OF MOTORS. The rapid acceleration of speed of
a motor when the load upon it is removed.
REEL. An arbitrary unit of linear measure for film approx-
imately a thousand feet.
REEL. The metal spool upon which the film is wound.
REFLECTION. The change of direction experienced by a
ray of light when it strikes a surface and is thrown back
or reflected,. Light is reflected according to two laws.
(a) The angle of reflection is equal to the angle of inci-
dence.
(b) The incident and the reflected rays are both in the
same plane which is perpendicular to the reflecting
surface.
REFRACTION. The change of direction which a ray of
light undergoes upon entering obliquely a medium of differ-
ent density from that through which it has been passing. In
this case the following laws obtain:
(a) Light is refracted whenever it passes obliquely from
one medium to another of different optical density.
(b) The index of refraction 'for a given substance is a con-
stant quantity whatever be the angle of incidence.
16 MOTION PICTURE PROJECTION
(c) The refracted ray lies in the plane of the incident ray
and the normal.
(d) Light rays are bent toward the normal when they
enter a more refracted medium and from the normal
when they enter a less refracted medium.
REGISTER. A term denoting facial expression of emotions.
RELEASE. The publication of a photoplay.
RETAKE. Rephotographing a scene.
REWIND. The process of reversing the winding of a film,
usually so that the end to be first projected shall lie on the
outside of the roll.
RE WINDER. The mechanism Vy which rewinding is accom-
plished.
RESISTANCE BOX. A box filled with resistance coils con-
nected in series.
RHEOSTAT. 'An instrument used to offer resistance to the
flow of current. Made of a number of metal coils connected
in series and mounted on a frame.
RUBBER COVERED WIRE. A cable either solid or strand-
ed with a rubber covering and an outer protective covering
of cotton braid. Used for mains for motion picture work.
SCENE. The action taken at a single camera setting.
SCENARIO. A general description of the action of a pro-
posed photoplay.
SCREEN. The surface upon which a picture is optically pro-
jected.
SECONDARY COIL. The coil of a transformer in which the
current is induced, connected to the lamp.
SERIES. An electrical connection where lamps are connected
so that they depend on each other for supply, the current
passing through each lamp successively.
SHOOTING A SCENE. Photographing the scene.
SHORT CIRCUIT. Two wires of opposite polarity coming
in contact with each other without any controlling device.
SHUTTER. The obscuring device, usually a revolving seg-
mental disc, employed to intercept the light during the move-
ment of the film in motion-picture apparatus.
Shutter Working Blade (also variously known as the cut-
ting blade, obscuring blade, main blade, master blade or
travel blade). That segment which intercepts the light
during the movement of the film at the picture aperture.
Shutter Intercepting Blade (also known as the flicker
blade). That segment which intercepts the light one or
more times during the rest or projection period of the film
to eliminate flicker.
SIXTY CYCLE A. C. This is when every part of the circuit
MOTION PICTURE PROJECTION 17
is 60 times positive and 60 times negative every second. The
current changes its flow of direction 60 times a second.
SINGLE PHASE. Using only two wires and one E. M. F.
sometimes called monophase or uniphase.
SINGLE PICTURE CRANK (sometimes referred to as trick
spindle). That spindle and crank on a motion-picture
camera which makes one exposure at each complete revo-
lution.
SLIDE (Stereo Slide). The transparent picture from which
a screen still is projected.
SLIDING FRICTION. The friction existing between two
bodies in sliding contact with each other.
SPEED REGULATOR. An attachment on machine (gen-
erally a friction disc arrangement) used to regulate the
speed of machine (not the speed of motor).
SPHERICAL ABERRATION. The reflected rays of con-
cave spherical mirrors do not meet exactly at the same point.
This is called spherical aberration.
SPLICING. Joining the ends of film by cementing.
SPLIT REEL. A reel having two or more picture subjects
thereon.
SPOT. The illuminated area on the aperture plate of a
motion-picture projector.
SPROCKET. The revolvable toothed member which engages
the perforations in the film.
STAGE CABLE. A cable containing twin conductors each
insulated from the other and the whole thing covered with a
composition covering. Used for temporary purposes.
STEP-DOWN TRANSFORMER. A transformer that steps
down the voltage and raises the amperage.
STEP-UP TRANSFORMER. A transformer that steps up
the voltage and lowers the amperage.
STEREOPTICON. A lantern for projecting transparent pic-
tures, i. e., lantern slides, often a double lantern for dis-
solving.
STILL. A picture from a single negative.
STRIKING THE ARC. The act of bringing the carbons of
an arc lamp together, and immediately separating them, thus
establishing the arc.
SWITCH BOARD. A board to which wires are led connecting
with cross bars or switches.
SWITCH, DOUBLE POLE. A heavy switch which connects
and disconnects two leads simultaneously.
SWITCH, KNIFE. A switch with knife-like blades used on
circuits carrying high amperage.
18 MOTION PICTURE PROJECTION
SWITCH, SNAP. A small switch made to give a sharp break
used on home lighting circuits.
SWITCH, THREE WAY. A switch so constructed that by
turning its handle, connection can be made from one lead to
either of two other leads, and also so that connection can be
completely cut off.
TAKE-UP (noun). The mechanism which receives and winds
the film after it passes the picture aperature. Generally
consists of a split pulley and tension spring, its use is to
drive and control the speed and tension of the reel taking
up the film in lower magazine.
TAKE-UP (verb). Winding up the film after it passes the
picture aperture.
TENSION SPRINGS. On gate of machine, used to give the
proper tension to film while passing aperture.
THREE WIRE SYSTEM. A system of distribution of elec-
tric current where three wires instead of two sets of two
wires are used. The middle or neutral wire acts as positive
wire for the negative, and as negative wire for the positive.
The advantage of the system is the saving of copper.
THREE PHASE. A system of electrical distribution making
use of three separate currents. These currents may be super-
imposed and generally only three wires are used in this trans-
mission.
THROW. Projection distance. Distance from front com-
bination of lens to screen.
TILT. The act of, or device for, moving a camera vertically
while in use.
TINTING. Coloring a film by dyeing the gelatine side of it.
TONING. Coloring a film by chemical action on the silver
image.
TRAILER. That piece of blank film attached to the end of
a picture series.
TRANSFORMER. An apparatus used on alternating cur-
rent systems to raise or lower the voltage.
TRANSVERTER. A motor generator set, an A. C. motor
connected to a D. C. generator.
TRICK CRANK. A camera crank giving a single exposure
for each turn.
TRICK-PICTURE. -A picture in which unnatural action ap-
pears.
TWO PHASE. An A. C. system of electrical distribution
making use of two currents of different phase. Can be ar-
ranged with either 8 or 4 wires.
VISION. A new subject introduced into the main picture,
MOTION PICTURE PROJECTION
19
by the gradual fading-in and fading-out of the new subject,
as, for example, to visualize a thought.
VOLTAGE. Electric motive force or pressure.
VOLTMETER. An instrument used to measure the electric
pressure.
WATT. The practical unit of electrical power. Equal to
amperes times volts.
WATT HOUR. Amount of watts times length of hours.
WORKING DISTANCE. The distance from the principal
focus of a lens to its nearest face; e. g., the distance from
the slide or film to the nearest lens of the objective.
20 MOTION PICTURE PROJECTION
MOTION PICTURE STANDARDS
The following have been adopted as standards by
the Society of Motion-Picture Engineers, and are
promulgated to encourage uniformity and standard
practice throughout the Industry as a whole. Their
early universal adoption will save the industry a
great deal of present annoyance and monetary loss.
FILM SPEED. A film movement of sixty feet per minute
through motion-picture mechanisms shall be considered as
standard speed.
FRAME LINE. The dividing line between pictures on
motion-picture film shall lie exactly midway between the
marginal perforations.
INTERMITTENT GEAR RATIO. The movement of the in-
termittent gear shall be expressed in degrees of rotation
during which the pin of the driver is in contact with the slot
of the driven gear. For example, a gear in which the pin is
engaged with the slot for one-quarter of a revolution of the
driver shall be called a 90-degree movement; that in which
the pin is engaged with the slot for one-sixth of a revolution
shall be called a 60-degree movement, etc.
LANTERN SLIDE MAT OPENING. A standard opening in
mats of lantern slides for use in conjunction with motion
pictures shall be 3 inches wide by 2*4 inches high.
THUMB MARK. The thumb mark spot on a lantern slide
shall be located in the lower left-hand corner next the reader
when the slide is held so as to be read against a light.
LANTERN STRIP. A red binding strip to be used on the
lower edge of the lantern slide.
PICTURE APERTURE. The standard film picture aperture
in a projecting machine shall be 0.906 inch wide and 0.6795
inch high, namely, 29/32" and 87/128".
PROJECTION ANGLE. The maximum permissible angle in
picture projection shall not exceed twelve degrees (12)
from a perpendicular to the screen surface.
PROJECTION LENS FOCI. The focus of motion-picture
projection lenses shall increase in ^4" steps to 8 inches and
from 8 to 9 in ^-inch steps.
PROJECTION LENS MOUNTING. Picture projecting
lenses shall be so mounted that the light from the film
MOTION PICTURE PROJECTION 21
picture aperture shall have an uninterrupted full path to the
rear component of the lens.
PROJECTING LENS HEIGHT. The standard height from
the floor to the center of the projecting lens of a motion-
picture machine shall be 48 inches.
PROJECTION LENS OPENING. The diameter of unit
opening for projecting lens holder shall be 1 15/16 inch.
PROJECTION OBJECTIVES. Shall have the equivalent
focal length marked thereon in inches and quarters and
halves of an inch, in decimals, with a plus (-f) or minus ( )
tolerance not to exceed 1 per cent, of the designated equiv-
alent focal length also marked by the proper sign following
the figure.
REEL. The approved standard reel shall be 10 inches in
diameter; iy 2 inches inside width; with 5/16-inch center
hole, with a key-way %" by %" extending all the way
through; a 2-inch hub; and a permissible flange wabble of
not more than 1/16-inch.
STANDARD PICTURE FILM. Shall be one and one-third
inches wide, and carry a picture for each four perforations-
the vertical position of the picture being longitudinal of
the film.
STANDARD REEL FILM. Shall have black film leaders,
with tinted (red, green or blue) trailers; should have mark-
ing thereon embossed rather than punched in the film; and
each reel of a multiple-reel story should end with a title, and
the next reel begin with the same title.
TAKE-UP PULL. The take-up pull on film shall not exceed
15 ounces at the periphery of a 10-inch reel or 16 ounces on
a (11-inch) reel.
22 MOTION PICTURE PROJECTION
'A Pocket Reference Book
FOR
Managers and Projectionists'
By JAMES R. CAMERON
Price One Dollar
THEATRE SUPPLY COMPANY
124 WEST 45xn STREET NEW YORK CITY
MOTION PICTURE PROJECTION 23
ELECTRICITY
No one knows exactly what electricity is, we do
not even know what it consists of, we do know that
electricity and magnetism are one and the same.
Electricity is not matter nor yet is it energy, al-
though it is a means of transmitting energy, and we
know how to handle this force for this purpose.
It is an undeniable fact that energy cannot be
created nor can it be destroyed, but we can convert
one kind of energy into energy of another kind. For
example, should we light a fire under a vessel con-
taining water we will convert the heat energy from
the coals to steam energy in the vessel containing
the water, and we could again change this steam
energy into mechanical energy, as is done with the
locomotive.
It is also possible to convert mechanical energy
into electrical energy, so by connecting the mechani-
cal energy created by the steam to a dynamo we
would produce electrical energy.
It is also possible to convert electrical energy into
mechanical energy. A motor is used for this purpose.
The word dynamo is used to designate a machine
which produces direct current as distinguished from
the alternator or generator which produces alternat-
ing current. A dynamo does not create electricity
but produces an induced electric-motive force which
causes a current of electricity to flow through a
circuit of conductors in much the same manner as a
pump causes water to flow through a pipe. The
point to be settled in the minds of those taking up
24 MOTION PICTURE PROJECTION
electricity is that the dynamo merely sets into mo-
tion something already existing, by generating suf-
ficient pressure to overcome the resistance to its
movement.
Although we speak of alternating and direct cur-
rent, it should be clearly understood that it is im-
possible to get a continuous current with a dynamo.
The current is really a pulsating one, but the pulsa-
tions are so small and follow each other so quickly
that the current is practically continuous.
Electromotive Force. When a difference of elec-
trical potential exists between two points, there is
said to exist an electromotive force, or tendency to
cause a current to flow from one point to the other.
This electromotive force is analogous to the pressure,
caused by a difference in level of two bodies of water
connected by a pipe. The pressure tends to force
the water through the pipe, and the electromotive
force tends to cause an electric current to flow.
Electromotive force is commonly designated by
the letters E. M. F. or simply E. It is also referred
to as pressure or voltage.
Current. A current of electricity flows when two
points, at a difference of potential, are connected by
a wire, or when the circuit is otherwise completed.
Similarly, water flows from a high level to a lower
one, when a path is provided. In either case the flow
can take place only when the path exists. Hence
to produce a current it is necessary to have an elec-
tromotive force and a closed circuit. The current
continues to flow only as long as the electromotive
force and closed circuit exists.
The strength of a current in a conductor is defined
MOTION PICTURE PROJECTION 25
as the quantity of electricity which passes any point
in the circuit in a unit of time. Current is desig-
nated by the letter C or /.
Resistance. Resistance is that property of mat-
ter, in virtue of which bodies oppose or resist the
free flow of electricity. Water passes with difficulty
through a small pipe of great length or through a
pipe filled with stones or sand, but very readily
through a large, clear pipe of short length. Like-
wise, a small wire of considerable length and made
of poor conducting material offers great resistance
to the passage of electricity, but a good conductor
of short length and large cross-section offers very
little resistance.
Resistance is designated by the letter R.
Volt, Ampere and Ohm. The volt is the practical
unit of electromotive force.
The ampere is the practical unit of current.
The ohm is the practical unit of electrical resist-
ance. The microhm is one millionth of an ohm, and
the megohm is one million ohms.
The International ohm, as nearly as known, is the
resistance of a uniform column of mercury 106.3
centimeters in length by one square milimeter in
cross-section at a temperature of zero centigrade.
The ampere is the strength of current which, when
pased through a solution of silver nitrate, under suit-
able conditions, deposits silver at the rate of .001118
gram per second.
The volt is equal to the E. M. F. which, when
applied to a conductor having a resistance of one
ohm, will produce in it a current of one ampere.
All substances resist the passage of electricity, but
26 MOTION PICTURE PROJECTION
the resistance offered by some is very much greater
than that offered by others. Metals have by far the
least resistance, and of these, silver possesses the
least of any. In other words, silver is the best con-
ductor. If the temperature remains the same, the
resistance of a conductor is not affected by the cur-
rent passing through it. A current of ten, twenty
or any number of amperes may pass through a cir-
cuit, but its resistance will be unchanged with con-
stant temperature. Resistance is affected by the
temperature and also by the degree of hardness.
Annealing decreases the resistance of a metal.
Conductance is the inverse of resistance; that is,
if a conductor has a resistance of R ohms, its con-
1
ductance is equal to .
R
Resistance Proportional to Length. The resis-
tance of a conductor is directly proportional to
its length. Hence, if the length of a conductor is
doubled, the resistance is doubled, or if the length is
divided, say into three equal parts, then the resis-
tance of each part is one-third the total resistance.
Resistance Inversely Proportional to Cross-Sec-
tion. The resistance of a conductor is inversely
proportional to its cross-sectional area. Hence the
greater the cross-section of a wire the less is its
resistance. Therefore, if two wires have the same
length, but one has a cross-section three times that
of the other, the resistance of the former is one-third
that of the latter.
As the area of a circle is proportional to the
square of its diameter, it follows that the resistances
MOTION PICTURE PROJECTION 27
of round conductors are inversely proportional to
the squares of their diameters.
Specific Resistance. The specific resistance of a
substance is the resistance of a portion of that sub-
stance of unit length and unit cross-section at a
standard temperature. The units commonly used are
the centimeter or the inch, and the temperature that
of melting ice. The specific resistance may there-
fore be said to be the resistance (usually stated in
microhms) of a centimeter cube or of an inch cube
at the temperature of melting ice. If the specific
resistances of two substances are known, then their
related resistance is given by the ratio of the specific
resistance.
Calculation of Resistance. It is evident that re-
sistance varies directly as the length, inversely as
the cross-sectional area, and depends upon the spe-
cific resistance of the material.
If a circuit is made up of several different mate-
rials joined in series with each other, the resistance
of the circuit is equal to the sum of the resistances of
its several parts. In calculating the resistance of
such a circuit, the resistance of each part should first
be calculated, and the sum of these resistances will
be the total resistance of the circuit.
Resistance Affected by Heating. The resistance
of metals depends upon the temperature, and the
resistance is increased by heating. The heating of
some substances, among which is carbon, causes a
decrease in their resistance. The resistance of the
filament of an incandescent lamp when lighted is only
about half as great as when cold. All metals, how-
ever, have their resistance increased by a rise in tern-
MOTION PICTURE PROJECTION
perature. The percentage increase in resistance with
rise of temperature varies with the different metals,
and varies slightly for the same metal at different
temperatures. The increase is practically uniform
for most metals throughout a considerable range of
temperature. The resistance of copper increases
about A per cent, per degree Centigrade. The per-
centage increase in resistance for alloys is much less
than for the simple metals. Standard resistance
coils are therefore made of alloys, as it is desirable
that their resistance should be as nearly constant as
possible.
QUANTITY, ENERGY AND POWER.
Quantity. The strength of a current is deter-
mined by the amount of electricity which passes
any cross-section of the conductor in a second;
that is, current strength expresses the rate at which
electricity is conducted. The quantity of electric-
ity conveyed evidently depends upon the current
strength and the time the current continues.
The Coulomb. The coulomb is the unit of quan-
tity and is equal to the amount of electricity which
passes any cross-section of the conductor in one
second when the current strength is one ampere. If
a current of one ampere flows for two seconds, the
quantity of electricity delivered is two coulombs, and
if two amperes flow for one second the quantity is
also two coulombs. With a current of four amperes
flowing for three seconds, the quantity delivered is 12
coulombs. The quantity of electricity in coulombs is
therefore equal to the current strength in amperes
multiplied by the time in seconds.
MOTION PICTURE PROJECTION 29
Energy. Whenever a current flows, a certain
amount of energy is expended, and this may be
transformed into heat, or mechanical work, or may
produce chemical changes. The unit of mechanical
energy is the amount of work performed in raising a
mass of one pound through a distance of one foot,
and is called the foot-pound. The work done in
raising any mass through any height is found by
multiplying the number of pounds in that mass by
the number of feet through which it is lifted. Elec-
trical work may be determined in a corresponding
manner by the amount of electricity transferred
through a difference of potential.
The Joule. The joule is the unit of electrical
energy, and is the work performed in transferring one
coulomb through a difference of potential of one volt.
That is, the unit of electrical energy is equal to the
work performed in transferring a unit quantity of
electricity through a unit difference of potential. It
is evident that if 2 coulombs pass in a circuit and the
difference of potential is one volt, the energy ex-
pended is 2 joules. Likewise, if 1 coulomb passes and
the potential difference is 2 volts, then the energy
expended is also 2 joules. Therefore, to find the
number of joules expended in a circuit, multiply the
quantity of electricity by the potential difference
through which it is transferred.
Power. Power is the rate of doing work, and
expresses the amount of work done in a certain time.
The horse-power is the unit of mechanical energy,
and is equal to 33,000 foot-pounds per minute, or
550 foot-pounds per second. A certain amount of
work may be done in one hour or two hours, and in
30 MOTION PICTURE PROJECTION
stating the work done to be so many foot-pounds
or so many joules, the rate at which the work is
done is not expressed. Power, on the other hand,
includes the rate of working.
It is evident that if it is known that a certain
amount of work is done in a certain time, the rate
at which the work is done, or the power, may be
obtained by dividing the work by the time, giving
the work done per unit of time.
The Watt. The electrical unit of power is the
watt, and is equal to one joule per second; that is,
when one joule of work is expended in one second,
the power is one watt. If the number of joules ex-
pended in a certain time is known, then the power in
watts is obtained by dividing the number of joules
by the time in seconds.
The power is obtained by multiplying the current
by the voltage, or by multiplying the square of the
current by the resistance.
The watt is sometimes called the volt-ampere.
For large units the kilowatt is used, and this is
equal to 1,000 watts. The common abbreviation for
kilowatt is K. W. The kilowatt-hour is a unit of
energy, and is the energy expended in one hour when
the power is one kilowatt.
Equivalent of Electrical Energy in Mechanical
Units. The common unit of mechanical energy is
the foot-pound, and from experiment it has been
found that one joule is equivalent to .7373 foot-
pound; that is, the same amount of heat will be
developed by one joule as by .7373 foot-pound of
work.
As one horse-power is equal to 550 foot-pounds
MOTION PICTURE PROJECTION 31
per second, it follows that this rate of working is
equivalent to
550
= 746 joules per second (approx.).
.7373
Hence one horse-power is equivalent to 746 watts.
Therefore, to find the equivalent of mechanical
power in electrical power, multiply the horse-power
by 746; and to find the equivalent of electrical
power in mechanical power, divide the number of
watts by 746.
Ohms Law. Ohms law is merely the fundamental
principle on which most of electrical mathematics
are worked.
A series of formulas used by electricians in figur-
ing voltage, amperage and resistance :
FORMULA 1
To find the amount of current flowing in a circuit divide the
voltage by the resistance, or
Electric Motive Force
Current =
Resistance
For instance, if we have a line voltage of 100 and our circuit
has a resistance of 5 ohms, then by dividing 100 by 5, we
would get our amperage.
5 ) 100 ( 20
100
so we would have 20 amperes.
FORMULA 2
To find the amount of resistance in a circuit, divide the voltage
by the amount of amperage drawn, or
MOTION PICTURE PROJECTION
Electric Motive Force
Resistance =
Current
For Instance, suppose we have a line voltage of 100 and are
using 20 amperes at arc lamp, then by dividing the 100
by 20 we would get the amount of resistance we have In
our circuit
20 ) 100 (5
100
to we would have 5 ohms resistance in our circuit
FOEMULA 8
To find the voltage of a circuit, multiply the amount of am-
peres drawn by the amount of resistance, or
Electric Motive Force = Amperes Times Resistance
For example: If we had 20 amperes at arc and our circuit was
offering 5 ohms resistance, then by multiplying 20 by 6 we
would get our voltage.
20 amperes
ohms
100 volts
To find Volt*. Multiply number of Amperes by amount of
Resistance.
To find Rffiftance. Divide Voltage by Amperage.
To find Amperage. Divide Voltage by Resistance.
To find Watt*. Multiply Voltage by Amperage.
To find Amp*. Divide Watts by Volts.
To find Volt*. Divide Watts by Amperage.
PICTURE PROJECTION
GENERATION OF ELECTRICITY
Everyone is acquainted with the horseshoe mag-
ajMJ the small pocket compass, and these two
articles will serve as an illustration.
- if one of the legs of the horseshoe magnet be
brought mar tl pu.s*, it will be found thai one
?h.- needle will be attracted to it, whilst if Uie
other leg be present. ito
Fie .
78
MOTION PICTURE PROJECTION
110 volt y 2 ampere lamps are connected across a
110 volt circuit, each dynamo supplying 2^ am-
peres at a pressure of 110 volts; which means a
total wattage of 550 W. for the ten lamps. Fig. 2
shows us the same two dynamos, now connected to-
gether in series, and the same ten lamps, this time
connected in series of pairs across a potential of 220
volts (on account of the dynamos being connected
in series). As the voltage in this case is just double
each lamp now draws 14 ampere instead of % am-
pere as in Fig. 1 which makes the wattage in this
case 220 X 2% = 550 watts, thus the wattage in
each case is the same, but in Fig. 2 we have made a
saving of 100 per cent, in copper, as we used two
wires only, against four in Fig. 1.
i
o
1
O
I
o
FIQ. 5.
MOTION PICTURE PROJECTION
79
The arrangement in Fig. 2 is open to objection,
however, as should one of the lamps burn out or be
turned off, its companion will also go out. This is
overcome in the three wire system by introducing a
third wire into the circuit (Fig. 3) thus providing
a supply or return wire to any of the lamps and
permitting any of the lamps to be cut out of the
circuit without affecting any of the others.
The three wire system is generally obtained by
connecting two dynamos of a like capacity in series
and connecting a third or neutral wire to a point
common to both dynamos. The dynamos being con-
nected in series, we get the added voltage of the
dynamos when connected between the two outside
V-
05
O
O O
\ o
FIG $.
80
MOTION PICTURE PROJECTION
wires, and the voltage of one dynamo only when con-
nected between either of the outside wires and the
neutral (Fig. 3).
No current will flow over the neutral wire, if the
system is kept balanced (the same amount of
amperage is drawn off either side of the system)
and the flow of current in the neutral wire at any
time is the difference between the amperage drawn
from either side.
Fig. 4 shows a three wire system, A and B, being
two 110 volt dynamos connected in series, C is the
positive wire, D the neutral wire and E the nega-
tive wire. The ten circles on either side of the neu-
tral wire represent lamps, each taking one ampere,
as we have the same amount of current (10 amperes)
r
MOTION PICTURE PROJECTION
81
drawn off either side, the system is balanced and
there is no flow of current in the neutral wire. The
ten amperes being drawn from dynamo A over posi-
tive wire C and after passing through the lamps re-
turning to dynamo B by way of negative wire E.
An unbalanced three wire system is shown in Fig.
5, taking it for granted that each of the lamps is
taking one ampere, we have four amperes on one
side and six on the other, 6 4 = 2, so our system
is unbalanced to the extent of two amperes, and this
represents the flow of current in the neutral wire.
Four amperes being drawn from dynamo A over
positive line C then after passing through the four
lamps on the upper side, the four amperes goes to
feed four of the lamps on the lower side, but as there
I
j
T
\
t
o
i
FIG. b.
MOTION PICTURE PROJECTION
are six lamps to feed on the lower side, the two extra
amperes are drawn from dynamo B over neutral
wire D (which under the circumstances acts as a
positive). So in Fig. 5, we have four amperes flowing
from dynamo A over positive line C, two amperes
flowing from dynamo B over neutral wire D, and six
amperes flowing to dynamo B over negative line E.
In Fig. 6 we have another unbalanced system, in
this case six amperes are drawn from dynamo A over
positive line C and after feeding the six lamps on
the upper side, four amperes are used to feed the
four lamps on the lower side, the two extra amperes
going back to dynamo A over the neutral wire D
(which now acts as a negative) and four amperes
going to dynamo B over negative line E.
With a three wire system, the idea is to keep the
system as near balanced as possible. For motion
picture work it is advisable to connect the machines
between the neutral wire and the outside, one ma-
chine on each side of the system. When using the
positive and neutral wires, the positive goes to the
top jaw of arc lamp and the neutral to the lower,
if you use the neutral and negative wires then the
neutral wire goes to top jaw of arc lamp and the
negative to the lower.
MOTION PICTURE PROJECTION
83
FUSES
A safety device used on your line to protect the
circuit.
A short length of fusable wire introduced in a cir-
cuit so that if the temperature of circuit should rise
above the rated capacity of fuse the wire will melt
and thereby open the circuit.
Fuses are made in different shapes and sizes, the
moving picture operator, however, will only be called
upon to handle the under-mentioned.
Copper-Tipped Fuse Link
Link Fuse. The link fuse is the fuse always used
in the booth, being of the open type it cannot be
readily boosted without same being plainly seen.
Enclosed or "Cartridge" Fuse
Section of Enclosed Fuse
84 MOTION PICTURE PROJECTION
Link fuses have no protective covering, so should
always be installed in a metal cabinet.
Cartridge Fuse. Made by connecting two metal
cap terminals with a short paper tubing. The two
metal caps are connected by a thin wire which runs
through the paper tubing, the tubing is filled with
some non-conducting powder.
Plug Fuses. Plug fuses are used for protecting
the house wiring and circuits carrying small amper-
age.
In fusing upon any circuit you must take into con-
sideration the size of the wire used and the amount
of amperage to be drawn. The fuse should be rated
under the carrying capacity of the wire with a suf-
ficient margin to allow the required number of am-
peres to pass over without overheating. The rating
of all fuses is marked on them. Never use a fuse not
marked.
Edison Fuse-Plug
MOTION PICTURE PROJECTION 85
TESTING FOR GROUNDS
Always remember that like poles repel each other
while unlike poles attract each other, in other words
the negative polarity is attracted by the positive
polarity, and vice versa, while the negative has no
attraction for negative nor the positive for positive.
The positive wire of one system will have no at-
traction for the negative wire of any other system 4
except its own, nor will the negative of one system
find any attraction in the positive of any other sys-
tem.
A ground is merely the current from one polarity
being attracted by the opposite polarity, through
the ground or some conducting medium other than
that in the circuit.
Supposing that we are working on a three
wire system and our neutral wire is grounded, and
that we take and connect one of the outside wires to
the upper jaw of arc lamp, and we connect the
neutral wire to the lower jaw (the neutral wire now
acts as negative to the -upper or positive wire). We
now ground the machine by connecting the metal
framework of machine to the conduit coming in
booth. Our machine now becomes grounded on the
neutral because we have made contact between the
frame of machine and the already grounded conduit.
Should we now connect our test lamp between the
upper jaw of arc lamp and frame of machine or lamp
house we will naturally get a light as we are con-
nected between the two polarities of the system.
86 MOTION PICTURE PROJECTION
Now should the arc lamp become grounded ( caused
we will say by the mica insulation coming out of jaw
connection) on the lower jaw it would mean that the
system is grounded on the negative polarity and the
arc itself is grounded on the negative polarity, and
this may or may not blow the fuse. But should it
be the upper jaw of lamp that becomes grounded
then our arc would be grounded on the opposite po-
larity to that of the machine, and thus cause a short
circuit.
To test for a ground in the lamp house, first dis-
connect the ground wire and connect the terminals
of test lamp between the upper and lower carbons.
We should now get a light, as we are connected be-
tween both polarities, this test merely shows that we
have current in our lamp.
Connect the test lamp between the upper car-
bon and the frame of lamp house, if we get a light
then our lower jaw is grounded, if we do not get light
then take it for granted that lower is free from
grounds.
Next test to see if the upper is grounded by con-
necting the test lamp between the lower jaw of arc
lamp and the frame of lamp house, if we get a light
then upper jaw is grounded. Always find the cause
of ground and remove same at earliest opportunity.
Before using the test lamp see that lamp is alright
and that it makes good contact in socket.
To test for a ground in the rheostat, use a bell set.
First connect the terminals of bell set between the
two binding posts of rheostat, and if rheostat is free
MOTION PICTURE PROJECTION 87
from open circuits you should get a ring, next con-
nect the terminals of bell set between one of the coils
or plates in rheostat and the iron frame, if you get
a ring it signifies that the rheostat is grounded, but
this test will not tell you which coil or plate is caus-
ing the ground. To find exactly where ground is,
proceed as follows : connect bell set between the first
coil and frame, if you get a ring, disconnect the first
coil, now connect between the second coil and frame,
if you get a ring disconnect the second coil, and do
the same to third and fourth coil, keep testing in
this manner till bell stops ringing, then the coil you
removed last was the coil that was grounded, so if
you have removed six coils and the bell stops ringing
when connected between the seventh coil and frame,
it was coil number six that was grounded.
If the rheostat is made of more than one section,
test each section separately and find which section
the ground is in, then proceed as above. This is to
save time.
88
MOTION PICTURE PROJECTION
MOTION PICTURE PROJECTION 89
THE PROJECTION ROOM
The room should contain everything necessary for
perfect projection, but nothing that can be done
without. Nothing but the projection of films should
be done in the room, an ante-room should be provided
with work bench and rewinder. The room should be
large enough to permit the free movements of the
operator or operators and should contain the neces-
sary closets and shelves for the operators' clothes,
tools, supplies, etc.
The operator should see that he has sufficient sup-
plies, such as fuses, lugs, film cement, asbestos cable,
condensers, various lubricants, carbons, mica,
brushes for motor, belting and a few of the necessary
parts for machine to replace those parts that are
liable to need replacing owing to wear, etc.
The operator should carry a kit of tools that will
permit him to do any repair work that he may be
called upon to do, the manager of today has very
little use for the would-be operator who shows up
on the job with a ten cent pair of pliers and a piece
of string.
If using rheostats then same should be installed
outside the projection room, but the control handles
should be placed so that they are within easy reach
of the projectionist, without his having to leave the
machine. The operator will thus find working con-
ditions a whole lot more comfortable.
All openings such as projection holes and port
holes must be so equipped with shutters that they
will all close automatically in case of fire.
90
MOTION PICTURE PROJECTION
MOTION PICTURE PROJECTION 91
A lot could be said about the position of booth and
the construction of same, but the trouble is that the
operator is generally the last man a manager or ex-
hibitor will consult in this matter when planning the
theatre, so the operator has to work under conditions
as he finds them.
One thing we would advise and that is, that the
walls of the booth should be painted a flat black (if
same has not been done). The size of all openings
should be reduced as much as possible, shade all
lights so that none of the light finds its way into the
auditorium of the theatre.
Each operator naturally has his own idea as to
just what constitutes an ideal projection room,
however, we are submitting in the following pages
a detailed description of the furnishings and fittings
of two well known and much discussed projection
rooms in New York City.
92
MOTION PICTURE PROJECTION
PLAN vitw OF lUwmo, PKOJCCTICN AND Moron GENERATOR ROOM
jfTt AU. WAi.it r c /tfcx AMMr(/rco..
Booth Plan, Reo Theatre, New York City
MOTION PICTURE PROJECTION
MCTKIW-X .. BEVELED E06
Plan for Single Machine Booth
94
MOTION PICTURE PROJECTION
i!s
ill
U!
I
it
93
L
-(.'-'
'*
K
MOTION PICTURE PROJECTION
95
O "-
8
96
MOTION PICTURE PROJECTION
MOTION PICTURE PROJECTION 97
AN IDEAL PROJECTION ROOM
"The largest theatre in the world," the New York
Capitol, has a projection room in keeping with the
rest of its luxurious appointments. The projection
room proper is 41 feet long and 19 feet deep and as
will be seen by the accompanying photographs, it is
furnished with everything necessary for perfect pro-
jection. Four of the latest Type S Simplex ma-
chines are responsible for the projection, each ma-
chine is equipped with an automatic arc control and
a metal cabinet for receiving hot carbon stubs.
There is also a special spotlight and a Simplex
Stereopticon, the spotlight is fitted with an 8-inch
iris diaphragm so constructed and arranged that
any sized spot can be immediately obtained, it is also
fitted with a curtain dissolve which allows the oper-
ator to gradually flood or dim the stage for special
lighting effects, and dispenses with the troublesome
masks.
Current supply is D. C. through 50-125 multiple
unit rheostats. The rheostats are placed in a special
room adjoining the projection room, the rheostat
controls being on the front wall near each projector
within easy reach of the operator. Each machine
draws 125 amperes at an approximate pressure of
68 volts.
98 MOTION PICTURE PROJECTION
MOTION PICTURE PROJECTION 99
The firing for the projectors is brought under
the floor up through the machine pedestals and then
to machine switch. Cool and comfortable working
conditions are assured at all times, the room having
4 windows opening directly into the street besides
two 24-foot exhaust fans ; a vent pipe runs from
the lamp house of each projector to the open air.
At the far end of the projection room is the re-
wind room, here are found a specially built film vault
for the storage of film, an enclosed motor rewind
equipped with an automatic stopping device in case
the film should break in the course of rewinding. The
comfort of the projectionists has not been over-
looked. An up-to-date washroom and lavatory to-
gether with a rest room for their special use adjoins
the projection room.
The throw is 197 feet and the picture is projected
on one of Robins' special white screens. The projec-
tion of the pictures and the musical score are syn-
chronized through the medium of the Robins speed
indicators.
100 MOTION PICTURE PROJECTION
PROJECTION ROOM INTERNATIONAL
CINEMA QUIPMENT CENTER
The projection room is 20 feet long by 10 feet
deep by 11 feet in height. It is built of 6-inch hol-
low tile, plastered on both sides. Floor is arched
reinforced cement with 2-inch covering of red on the
top, which renders the booth neat in appearance and
easily kept clean.
Placed in the bottom of the booth are four 11
by 16-inch openings covered with fine mesh screen
providing fresh air intake. An 18 by 24-inch vent
flue leading to the outside carries away the warm air.
This flue has a double opening in the booth, one
which is covered by a grill, and in the other open-
ing is placed an electric ventilating fan, which is
controlled through the switchboard. By arranging
the exhibits in this manner it does not impede the
free passage of air.
There are eight openings in the booth. Each is
protected by the International Fire Shutter System,
which consists of kalomein frames built into the wall
with channel iron slideways attached into which are
fitted l/^-inch asbestos fire shutters. The shutters
are suspended by chains with fuseable links from a
pipe which runs along the front wall of the booth,
and is controlled by gravity when a fuse melts and
releases a string, the weight turns the pipe and drops
all shutters.
The fire shutter is very nea"t in appearance and
extremely effective.
MOTION PICTURE PROJECTION 101
There are two indirect fixtures in the booth which
are controlled by push button placed adjacent to
the entrance of the booth. About 12 inches from
the front wall of the booth, and directly in front of
each machine, is a drop light with a Crescent lamp
guard and porcelain socket. The lighting of the
booth is all on direct current.
Fig. 1
There is a signal telegraph controlled from the
review desk in the interior of the theatre and a return
call system ; also an extension Bell telephone con-
necting with the main switchboard of the Interna-
tional Cinema Quipment Centre. For the storage of
102 MOTION PICTURE PROJECTION
film during the course of projection the two 15-inch
5-section Safe-T-First cabinets are used.
Directly in the rear of the booth is a large kalo-
mein bench 6 feet long by 18 feet wide, which is used
as a rewinding table, and the lower portion, which
is divided into drawers, is used for accessories and
supplies.
Fig. 2
There is also provided an automatic sprinkler
system in the booth, fire extinguishers and pails.
The electric service consists of 110/220 volt Edi-
son D. C., 110/220 volt single phase 60 cycle A. C.
and 220 volt two phase A. C. This power is supplied
direct from the lighting company on a special service
MOTION PICTURE PROJECTION 103
run from the basement. Directly behind the ma-
chines in the rear wall of the operating room is a
special control board designed by J. E. Robin. This
board is 6 feet square of a dead face type. All
meters and switches operate from the front and are
back connected. The board is built of blue Vermont
marble 2 inches in thickness.
Fig. 3 shows the appearance of the front and Fig.
4 the rear. On the face of the board are mounted
two Weston D. C. ammeters, two Weston A. C. am-
meters and one Weston D. C. and one Weston A. C.
volt meters. The six hand wheels directly under-
neath the meters control volt and ammeter switches,
rendering it possible to read the amperage or voltage
on either side of the line, or the arc, and on any
control device being tested. Each D. C. ammeter is
provided with five interchangeable shunts, and each
A. C. ammeter with three current transformers,
which are shown to the left of the photograph Fig. 4.
The A. C. ammeter has a push button underneath in
the circuit which is connected with a multiplier to
permit reading on the low voltage of transformer.
The two other hand wheels shown on the left are on
the right side of the booth control field rheostat, and
the upper row of switches machine motor circuits
and lighting, vent fans and Mazda lamp A. C. trans-
formers. The lower row are the four main line
switches two provided for the generator switch-
board and two for the engines.
As shown on photograph Fig. 4 12-200 ampere
Kleigl plugging pockets. These are underneath the
front of the board and underneath the booth directly
from each projecting machine is run in conduit, con-
104
MOTION PICTURE PROJECTION
cealed in the floor two No. wires, which come out
through a furrel in the bottom of the board, of
which there are four, and terminate in five-foot long
generator cable with a Kleigl plug attached.
Directly underneath the projecting machine in the
booth is a ventilator, where are located A. C. arc
transformers, A. C. Mazda transformer, D. C. and
A. C. rheostat and D. C. Mazda lamp rheostat. All
Fig. 3
MOTION PICTURE PROJECTION 105
connections from these devices run direct from the
main switchboard and terminate in the box of main
switchboard. It is possible, therefore, by plugging
in one of the four machines into the pockets to oper-
ate on the different kinds of apparatus either A. C.
or D. C., running one or four machines simulta-
neously.
All wiring of conduits are concealed in the floor
and walls of the booth, and the wires leading to the
machines, meters and arc switch come up directly in
the centre of pedestal. Set flush in the wall directly
underneath the lookout hole in front of each pro-
jector is a special control panel board of blue Ver-
mont marble with a volt meter and ammeter mounted
on the face of the same, and Robin Cinema electric
speed indicator. There is also provided a radial
rheostat switch connected to the multiple unit rheo-
stat. This switch is used to control the amperage
at the arc which may be run from 5 to 100 amperes.
This marble cover on panel board is arranged with
hinges to open down into the booth, thus rendering it
accessible.
In addition to the general booth equipment there
is shown to the rear of the booth in photograph the
motor generator testing department. In this space
are five different types of motor generators, both
single and two phase, with special panel board in
front of each one with control switches and instru-
ments.
Each generator is mounted on an iron pan, which
is attached to frame and rests on cork and rubber
to prevent noise when in operation. The top of the
platform is covered with a battleship linoleum bound
106
MOTION PICTURE PROJECTION
with brass. The switchboard shown in the centre
controls the motor generator sets, and is intercon-
nected with the main switchboard in the booth. This
board is also dead type with the front of the blue
Vermont marble of 2-inch thickness, with all switches
back connected and enclosed with a steel cabinet with
two doors making it accessible from the rear. On
the upper row are instruments consisting of two two-
Fig. 4
MOTION PICTURE PROJECTION 10T
phase Weston indicating watt meters, one Weston
single indicating watt meter. This serves to show
the wattage used in running the various machines.
The two lower machines are without meters, which
are connected across the two, coming out of the bot-
tom of the board, which indicate in watts the power
being taken in any of the generators. In this man-
ner the current being used can easily be determined.
The voltage and amperage may be obtaind from the
meters on the individual panel or from the interior
of the instruments in the booth.
There are 10 plugging pockets on the board, two
being connected with each machine. The two cables
shown coming out of the board connect with the
main switchboard in the booth. It is possible, there-
fore, to plug one or two arcs on any of the genera-
tors or for comparative test to run two generators
simultaneously with one arc on each.
This switchboard contains both current trans-
formers, voltmeter multipliers and resistances and
other necessary switches, cutouts and accessories.
The machines consist of two Type "S" Simplex
one Simplex Mazda equipment with A. C. and D. C.
regulator and one Simplex with 1J^ to 1 shutter
5 to 1 movement and Argus sheck adapter. This
machine is also equipped with Feaster non-rewind.
All projectors are enameled battleship gray with fit-
tings in nickel. Each machine is equipped with volt
and ampere meters on front panel, also Robin Cinema
electric speed indicators, lamp house with Simplex
arc periscope, which throws the image of the arc on
the walls or ceiling. The Mazda lamp, A. C. trans-
formers and D. C. rheostats are located in the floor
108
MOTION PICTURE PROJECTION
of the booth, and are controlled from the interior by
hand wheels somewhat similar to those used in the
pilot house aboard ship.
Figs. 5 and 6
MOTION PICTURE PROJECTION
109
110
MOTION PICTURE PROJECTION
lit
I
MOTION PICTURE PROJECTION
111
Floor Plan
Orchestra and Balcony
Visual Screens and Projection Angles. Modern Theatre Pro-
jection Layout to Determine Size and Position of Screen and
Height Above Stage.
112
MOTION PICTURE PROJECTION
LONGITUDINAL SECTION
t
Floor Plan, Single Floor Theatre
MOTION PICTURE PROJECTION 113
WORKING PRINCIPLE OF ELEMENTARY
PROJECTION MACHINE
By turning the operating crank A, counter clock-
wise, the main shaft B, is driven through the 4 to 1
reduction chain drive Z>, a steady turning motion
being caused by the fly wheel C, this in turn operates
the upper steady feed sprocket E, through the 4 to 1
reduction gear F, thus the teeth of E sprocket which
mesh with the perforations in the film, feed the film
at a constant rate, the film being held against E by
pressure roller G. A film loop or length of loose
film is thus maintained between E and the steady
drum H. The film is fed past the film gate inter-
mittently by the intermittent sprocket /, operated
by the Geneva movement K, the latter producing a
quick quarter turn of 7, followed by a relatively long
rest during which the main shaft B makes one revo-
lution. The barrel shutter L, by a 2 to 1 gear with
the main shaft and proper timing, operates to cut
off the light rays from the screen during each move-
ment of the intermittent sprocket /, and to admit
the light during the intervals that / remains sta-
tionary. The synchronous operation of the inter-
mittent sprocket and the shutter is very clearly
shown in the diagram. A lower steady feed sprocket
My which operates at the same speed as the upper
sprocket E, maintains a lower feed film loop N, and
114
MOTION PICTURE PROJECTION
ING GEAR WHEELS
4 TO I REDUCTION
MOTION PICTURE PROJECTION 115
feeds the film to the lower reel 0. Because of the
increasing diameter of the roll of film due to wind-
ing the film on reel 0, the velocity of rotation of
must be allowed to vary; this is accomplished by
means of the belt drive P, the belt permitting slip-
page below the maximum speed. It should be care-
fully noted that the total revolutions made by each
of the three sprockets E, I, and M, is the same, the
only difference being that the motion of E and M is
constant while that of I is intermittent.
116 MOTION PICTURE PROJECTION
Books by the Same Author
Pocket Reference Book for
Managers and Projectionists
Price One Dollar
Elementary Text Book on
Motion Picture Projection
Price Two Dollars
Electricity for Motion Picture
Operators
Price Two Dollars
Motion Picture Optics
(In Preparation)
THEATRE SUPPLY Co,
124 WEST 45TH STREET
NEW YORK CITY
MOTION PICTURE PROJECTION 117
LIGHT
That light travels with a speed, which is much
greater than the speed of sound is shown by the fact
that the flash of a distant gun is always seen long
before the sound of the report is heard and that
lightning always precedes thunder.
For most purposes it is sufficiently accurate to
take the velocity of light as 186,000 miles per second.
Light always travels out from a source in straight
lines.
Up till the year 1800, the Corpuscular theory of
light was the one most generally accepted, that light
consists of streams of very minute particles, or cor-
puscles projected with the enormous velocity of 186,-
000 miles per second from all luminous bodies. The
facts of straight line propagation and reflection are
exactly as we should expect them to be if this were
the nature of light.
A usual hypothesis which was first completely for-
mulated by the great Dutch physicist Huygens
(1629-1695), regarded light like sound, as a form of
wave motion. This hypothesis met at the first with
two very serious difficulties; in the first place light,
unlike sound, not only travels with perfect readiness
through the best vacuum which can be obtained with
an air pump, but it travels without any apparent
difficulty through the great interstellar spaces which
are probably infinitely better vacua than can be ob-
tained by artificial means. If, therefore, light is a
wave motion, it must be a wave motion of some me-
dium which fills all space and yet which does not
118 MOTION PICTURE PROJECTION
hinder the motion of the stars and planets. Huygens
assumed such a medium to exist, and called it ether.
The second difficulty in the way of the wave theory
of light, was that it seemed to fail to account for the
fact of straight line propagation. Sound waves,
water waves and all other forms of waves with which
we are familiar bend readily around corners, while
light apparently does not. It was this difficulty
chiefly which led many of the famous philosophers,
including the great Sir Isaac Newton, to reject the
wave theory and to support the projected particle
theory.
Within the last hundred years, however, this diffi-
culty has been completely removed and in addition
other properties of light have been discovered, for
which the wave theory offers the only satisfactory
explanation. If the wave theory is to be accepted, we
must conceive with Huygens, that all space is filled
with a medium, called the ether, in which the waves
can travel. This medium cannot be like any of the
ordinary forms of matter ; for if any of these forms
existed in interplanetary space, the planets and the
other heavenly bodies would certainly be retarded in
their motion. As a matter of fact, in all the hun-
dreds of years during which astronomers have been
making accurate observation of the motion of hea-
venly bodies no such retardation has ever been ob-
served. The medium which transmits light waves,
must therefore have a density which is infinitely
smaller even in comparison with that of our lightest
gases. The existence of such a medium is now uni-
versally assumed by physicists.
Just as sound waves are disturbances set up in the
MOTION PICTURE PROJECTION
119
air by the vibrations of bodies of ordinary dimen-
sions, so light waves are disturbances set up in the
ether probably by the vibrations of the minute cor-
puscles or electrons, of which the atoms of ordinary
matter are supposed to be built up. Since these cor-
puscles are extremely small in comparison with ordi-
nary bodies it is not surprising that their rates of
vibration are enormously larger than the vibration
rates of tuning forks, or other bodies which send out
sound waves. Just how these corpuscles are set into
vibration and in just what manner they vibrate, we
cannot say as yet with certainty, but since we do
know that an increase in the temperature of all
bodies means an increase in the agitation of the mole-
cules and atoms of which these bodies are composed.
It is not surprising that the vibrations which com-
municate light waves to the ether take place in
general in bodies which have a high temperature and
that the hotter the body becomes the more intense
becomes the light waves which it emits.
i
Snaplite Lens
120
MOTION PICTURE PROJECTION
PRINCIPLES OF OPTICAL PROJECTION
The process is almost the reverse of ordinary
photography. For instance, in photography a scene
by means of the photographic objective or lens is
photographed and a reduced image is obtained on
ground glass. This glass is replaced by a sensitized
plate and by the use of chemicals the image is fixed
thereon.
In projection the process is reversed, that is, a
transparent slide is made from the picture, or the
roll of film taken with the motion picture camera is
developed and used in the motion picture machine
(the projector). By means of a condensed light
they are strongly illuminated and with an objective
lens an enlarged image is projected upon the screen,
this screen image corresponding to the real objects
photographed. The principles of optical projection
for motion picture machine will readily be understood
from the diagram below.
Showing the Optical System of a Moving Picture Circuit and
How Kays of Light Travel from Arc E to Screen S
MOTION PICTURE PROJECTION 121
At E is an electric arc or other suitable illuminant,
the light from which is caught up by the condenser C.
This condenser is an arrangement of lenses so con-
structed as to gather up the greatest volume of light
possible and to concentrate the light which it
gathers at the center or diaphragm plane of the
objective when the objective is located at the proper
distance from the film, which distance is determined
by the focal length of objective lens.
The film should be placed at such a point that
the entire area of the aperture in gate is fully illu-
minated, and it should also be placed so that the
greatest number of light rays possible should pass
through it.
Proceeding from the slide D or film F the light
passes through the objective 0, where the rays cross,
and the object is therefore reversed, by means of the
objective, the object is also imaged or delineated
upon the screen S, the degree of sharpness or flatness
of the image depends upon the optical connection of
the lens.
Great care should be taken to line up properly the
arc, condensers and the objective lens, as under the
best of conditions less than 5% of the light from arc
reaches the screen.
122 MOTION PICTURE PROJECTION
LENSES
The optical system of a moving picture circuit
comprises :
(a) The arc lamp or mazda lamp.
(6) The condensers.
(c) The lens, or objective.
The optical system is a very important one and
one that has long been neglected by the majority of
operators. A number of men who have been operat-
ing machines for years have never taken the lenses
apart and have no idea of the different combinations
making up the objective lens.
There is no motion picture book published that we
know of which goes far enough into this matter, and
we would advise anyone desirous of getting all the
information possible on lenses to study the books
dealing with this subject that may be found in the
various libraries.
The following is an outline of what an operator
should know, and has been gathered from several
books dealing with optical systems and lenses.
Reflection. The change of direction experienced
by a ray of light when it strikes a surface and is
thrown back or reflected. Light is reflected accord-
ing to two laws :
(a) The angle of reflection is equal to the angle
of incidence.
(6) The incident and the reflected rays are both
in the same plane which is perpendicular to
the reflecting surface.
MOTION PICTURE PROJECTION 123
Refraction. The change of direction which a ray
of light undergoes upon entering obliquely .a medium
of different density from that through which it has
been passing. In this case the following laws obtain :
(a) Light is refracted whenever it passes
obliquely from one medium to another of
different optical density.
(6) The index of refraction for a given sub-
stance is a constant quantity whatever be
the angle of incidence.
(c) The refracted ray lies in the plane of the
incident ray and the normal.
(d) Light rays are .bent toward the normal
when they enter a more refracted medium
and from the normal when they enter a less
refracted medium.
A lense may be defined as a piece of glass or other
transparent substance with one or both sides curved.
Both sides may be curved, or one curved and the
other flat.
The object of the lens is to change the direction of
rays of light and thus magnify objects or otherwise
modify vision.
Lenses may be classed as :
Double convex Double concave
Piano convex Piano concave
Concavo convex Convexo concave
The focus of a lens is the point where the refracted
rays meet.
Spherical Aberration. The reflected rays of con-
cave spherical mirrors do not meet exactly the same
point. This is called spherical aberration.
124 MOTION PICTURE PROJECTION
Effect of Spherical Aberration. It produces a
lack of sharpness and definition of an image. If a
ground glass screen be placed exactly in the focus
of a lens the image of an object will be sharply de-
fined in the center but indistinct at the edges, and if
sharp at the edges it will be indistinct at the center.
To avoid this a disc with a hole in the center is placed
concentric with the principal axis of the lens, thus
only the center part of the lens is used.
Chromatic Aberration. When white light is passed
through a spherical lens, both refraction and disper-
sion (the decomposition of white light into several
kinds of light) occur. This causes a separation of
the white light into the various colors and causes
images to have colored edges. This effect which is
most observable in condenser lenses is due to the un-
equal refrangibility of the simple colors.
Achromatic Lenses. The color effect caused by
the chromatic aberration of a simple lens greatly im-
pairs its usefulness. This may be overcome by com-
bining into one lens, a convex lens of crown glass
and a concave lens of flint glass.
Back Focal Length. The distance from the back
of the lens to the film in the gate of machine while the
film is in focus on the screen. (Written B. F.)
Equivalent Focus. The distance from a point half
way between the back and front combination of
lenses to the film in the gate while picture is in focus
on screen.
Can be obtained by measuring the distance between
the front and back combination then dividing by
two and adding the result to the back focal length.
( Written E. F.)
MOTION PICTURE PROJECTION
125
Objective Lens. The objective lens of a moving
picture machine generally consists of four lenses, two
in the front combination and two in the rear. The
two lenses in the front are cemented together with
Canada Balsam and called the compound lens. The
back combination consists of two lenses separated by
a metal ring, called the duplex lens.
The convex or greatest convex side of a lens al-
ways faces the screen.
It is absolutely necessary to keep the lenses clean,
it will be impossible to get good definition or sharp
focus on the screen if the objective lens is not scrupu-
lously clean. Never place the fingers on the glass
Fig.l Fig.2
Fig.4
Figures 1 and 2 the crater of arc needs adjusting laterally
to right or left
Figures 3 and 4 the crater too high or too low
Figures 5, 6 and 7 the crater is too near or too far away
from condenser
Figure 8 shows arc in correct position
126 MOTION PICTURE PROJECTION
surface of lens, as though it may not show when
looking through the lens it will undoubtedly affect
the definition of picture on screen.
Condenser lenses should be cleaned every day, and
the objective lens once or twice a week. It will not
be found necessary to take the lens apart to do this,
as it will only be the exposed glass surfaces that will
need attention. Use a clean soft handkerchief for
this purpose. The lens can be taken apart every
three or four months and all surfaces thoroughly
cleaned, great care should be taken when taking the
lens apart so that you get the lenses back in the
same position and order.
Successful results in projection depend largely
upon the correct adjustment of the lamp, which must
throw a brilliantly illuminated clear circle on the
screen. After the objective is focused as will be
evidenced by a sharp, clear image on the creen,
examine the illuminated circle. If the light be cen-
tered and the lamp correctly adjusted, the circle
will be entirely free from coloration or shadows. In
Figures 1 and 2 the crater of arc needs to be proper-
ly adjusted laterally, it being as shown too far to
the right or left. Figures 3 and 4 show the crater
too high or too low. In Figures 5, 6 and 7 the crater
is too near or too far away from condensers. Figure
8 shows it in right position, the screen being free
from all shadows or ghosts.
Fig. 9 shows the various lenses: (a) double convex;
(6) piano convex; (c) concavo convex; (d) double
concave; (e) piano concave; (/) convexo concave.
MOTION PICTURE PROJECTION
127
The first three are thicker at the center than at
the border, and are called converging; the second
three which are thinner at the center are called di-
verging.
B
Fig. 9
The Gundlach-Manhattan Optical Co., makers of
the Gundlach Projection Lens, issue the following
data regarding Lenses.
The Manufacture of lenses presents many difficult
problems for the optician to contend with because of
the peculiar characteristics of optical glass as well as
the fact that it is not a material easily worked owing
to its hard, brittle nature. To produce lenses that
are well corrected in the optical sense and maintain
a uniform standard of' quality requires not only
scientific knowledge of optics and mathematics of a
high order to compute the formula but also the ut-
most skill and precision must be used during the
mechanical operations to obtain the desired result.
Even then it depends upon a master optician for the
final adjusting and testing before the lens is ready
for market because a good lens may be spoiled by
improper mounting. In this respect lenses are dif-
ferent from articles made of other materials which
128 MOTION PICTURE PROJECTION
can readily be made to conform to dies, patterns or
blue-print specifications with certainty that when
these are followed, the finished article will be perfect.
Each lens goes through several operations of
grinding and polishing and a stray bit of grit may
scratch a finished surface at the last moment, or
lenses will crack or chip in handling, adding spoilage
to the cost of manufacture.
A Projection Lens contains three distinct kinds of
glass, each lot of glass has slightly different proper-
ties and as one melt never includes more than a few
hundred pounds this necessitates a constant modifi-
cation of formulae with a corresponding changing
of tools which involves a big expense.
All this, of course, applies to a maintainance of a
standard of quality and explains why ordinary pro-
jection lenses made with no special care and taken as
they come naturally cost a great deal less than
Gundlach Projection Lenses which must all pass the
same tests and reach a fixed standard of quality be-
fore leaving the factory. Further, lenses of large
aperture require more care in grinding and polishing
than lenses of less curvature and their adjustment is
more sensitive. Besides, the larger lenses must be
made separately while those of smaller diameter with
flatter surfaces can be made two or more at a time
reducing the cost of manufacture proportionately.
It is an axiom of optics that the best lens is never
too good for the purpose and this is particularly true
as regards projection, it being obvious that a poor
lens makes a picture which is unsatisfactory to a
large number of people and the theatre owner or
producer suffers in consequence by criticism of the
MOTION PICTURE PROJECTION 129
show and loss of business. Now, a poor lens not only
will not focus sharply but the image is flattened and
lacks contrast because what should be black becomes
gray and light and shade gradations of the film im-
age are not reproduced in their proper values.
Gundlach Projection Lenses on the contrary give
uniformly sharp definition with the utmost illumina-
tion and the picture is brilliant because all the con-
trast of the film is preserved while the shadows show
more detail due to the additional light obtained by
their large working aperture.
The Screen Picture
The size of the film image is 24x1" and the opening
in the aperture plate has been standardized by the
principal machine manufactures at our suggestion
and is now 29/32" wide with the height *A of the
width. The picture is magnified in the same propor-
tions, therefore, the screen must be 9 inches high for
each foot in width. For example, 9'xl2', 10'6"xl4"
or 12'xl6'. A picture 16 ft. wide requires a magnifi-
cation of the film image of about 212 diameters or
nearly 44,944 times the size of the original.
The importance of standardization of the opening
in the aperture plate may be realized from the fact
that the two sizes formerly used 15/16!' wide and
29/32" wide with a difference of only 1/32" would
result in a difference of about 6 inches between the
width of pictures made with matched lenses for a
picture 16 ft. wide so that pictures of the same size
could be obtained only by using lenses of different
focal lengths, an inconvenient and difficult method of
securing this result.
130 MOTION PICTURE PROJECTION
It is our opinion that the quality of the picture is
more important than its size, or, in other words, we
must have perfect projection as the first consider-
ation. Owing to the unavoidable loss in definition
and illumination incidental to an increase in magnifi-
cation it is advisable to keep the size of the picture
within a reasonable limit which we think is about
12x16. Above this size the surface area increases
very rapidly with each additional foot in width. The
distance the picture is projected is not so important
unless it necessiates the use of lenses of abnormally
short or long focus.
Theoretically, there is a loss of light in inverse
ratio to the square of the distance, but in practice
a picture of a given size can be projected within a
reasonable distance without any noticable change in
luminosity. Obviously this imposes a limitation to
the size of theatres, therefore it is not advisable to
make a theatre so large that good projection cannot
be secured. The best results are obtained with lenses
ranging between 4" and 7^" focal length and any
deviation from these is not advisable.
The picture is projected from the same film
whether it is thrown 25 ft. or 150 ft. while an en-
largement of the picture is secured only by magnifi-
cation of the film image with a consequent depreci-
ation of the light by spreading it over a greater
surface. The definition is impaired as the natural
result of magnifying a film image which is not ab-
solutely sharp to begin with. On the contrary, a
difference in the distance does not bring these factors
into consideration although other difficulties arise if
an effort is made to produce too large a picture with
MOTION PICTURE PROJECTION 131
a very short focus lens or a comparatively small pic-
ture with a relatively long focus lens. The thing to
avoid is extreme or abnormal conditions because the
best result can be obtained only by being careful that
each factor having an influence upon the quality of
the picture is normal and efficient. Most important
of these is Gundlach Projection Lenses which insure
uniform definition with a brilliant image and the ut-
most luminosity. We differentiate between brilliancy
of the image and the working aperture of the lens or
the amount of light it collects and transmits because
the former is determined by its color correction which
if good, will preserve the contrast of the film and if
poor, will flatten the image while luminosity is merely
the inevitable result of making the diameter large in
proportion to the focal length.
Three principal factors govern the illumination of
the picture, first the light source including its ad-
justment, current consumption and condenser system
by which the film is illuminated.
Next is the working aperture of the projection lens
or the ratio between its diameter and focal length.
The third is the size of the picture or its surface
area.
The working aperture of the lens is the only one
in which we are directly interested.
This ratio in Gundlach Projection Lenses is car-
ried out to the highest degree with resulting aper-
tures of F.2. to F.3.5. according to the focal length
is not being practical for many reasons to maintain
a uniform aperture of F.2.
That the size of the picture is an important con-
sideration is evident as it must be clear that the
132 MOTION PICTURE PROJECTION
same amount of light spread over a larger surface
will be weaker.
For comparison we give the following examples:
Size of Picture Surface Area Magnification
9x12 108 sq. ft. 158.88 diameters
12x16 192 sq. ft. 211.84 diameters
15x20 300 sq. ft. 264.80 diameters
The Projection Lens
This we have already mentioned as being the ratio
between the diameter and focal length and this deter-
mines the amount of light transmitted by lenses of
all kinds. Obviously there must be a physical limi-
tation to this and in practical optics this is 1 2, so
the diameter cannot be more than half the focal
length. Even to attain this result is an achievement,
it involves making lenses with strong curves, each
made separately with the utmost care and great pre-
cision in mounting and the adjustment of the com-
ponents of the complete lens in relation to each other.
This means the distance from the optical center
of the lens to the point where it defines a sharp image
when focused for infinity and this measurement can
be made accurately only by optical means. Com-
mercially we grade the focal lengths in quarter inches
in engraving the cells but we mark the exact focal
length in hundredths of an inch on the wrapper and
use this measurement in filling orders.
To cite an instance a 16 ft. picture at 99 ft. re-
quires a lens of 5.60 focus. A lens of exactly 5^2
inch (5.50) focus would make the picture oversize
and 534 focus would be too long. To meet this con-
MOTION PICTURE PROJECTION 183
dition, we would make a selection from 5%" lenses
in stock of those the nearest to 5.60" focus but longer
rather than shorter. . Of course there is a possibility
in every case that an error in measuring the distance
will be a disturbing factor and some allowance should
be made by the customer for some difference between
the size of the picture and screen which is unavoidable
and easily painted out.
Lenses are matched by selection as the focal length
cannot be modified after they are finished. In manu-
facturing they deviate to some extent from the focal
length prescribed by the optical formula running
both under and over for which reason they are not
necessarily the exact focal length engraved upon the
mounts. For example, a 4" lens may vary within the
quarter inch from 3.95" to 4.20", it being our practice
to mark the mounts within 5/100" under to 20/100"
over of the actual focal length and it will be per-
ceived that two lenses marked with the same focal
length may at the most have a difference of %" and
matching for pictures of the same size necessitates
that both lenses shall be exactly the same focal
length. This being the case the lenses must be match-
ed when they leave our factory unless a lens to be
duplicated is sent to us so we can measure it or if
it was purchased from us we will have a record of
its focal length which we can locate if given the order
number or date of invoice. The exact focus in hun-
dredths of an inch is shown by our invoices in par-
enthesis, for example, (4.36), and purchasers should
make a note of this to faciliate placing repeat orders
for duplicates when they wish to match a lens or
replace one which has been damaged.
134 MOTION PICTURE PROJECTION
This system has proven a great convenience to
many of our customers and constitutes a real service
which adds greatly to our detail in making and sup-
plying lenses. Sometimes we are called upon to
match or duplicate a lens we sold several months or
years ago, and it is quite an advantage to the custom-
er to get a new lens that will make the picture the
same size it was before without any loss of time.
It should be noted by every user of a projection
lens that the components are not interchangeable and
no liberty whatever should be taken with the arrange-
ment or adjustment of a lens. A broken element can-
not be replaced unless the complete lens is returned
for repairs and the broken parts should be preserved
as they may be useful in determining the exact origin-
al focal length, otherwise this may be changed by
replacing the broken lens. Odd combinations or lens-
es are absolutely of no value and we cannot under-
take to utilize them to make up complete lenses or
for repairs.
The condition of many lenses sent in to us in-
dicates great carelessness in handling them and Pro-
jectionists should be cautioned to handle them more
gently. There is positively no excuse for so many
scratched surfaces, broken lenses and ruined mounts
after allowing for reasonable accidents.
The terms quarter and half size have no real place
in optical nomenclature although commonly used.
No doubt they originated in the early days of photog-
raphy when applied to portrait lenses used for quart-
er size (3/4x4%) and half size (4)4x6^) cameras.
These were the first lenses used for projection and
eventually each size was made in a number of different
MOTION PICTURE PROJECTION 135
focal lengths. The Projection Lenses of to-day are
made by a modification of the formula of the original
Petzvel Portrait Lens which we have brought to per-
fection with the improved optical glass at our com-
mand. The sizes of Gundlach Projection Lenses are
numbered to prevent them from being unfairly com-
pared or confused with so-called quarter and half size
lenses of smaller diameter and less light efficiency.
We wish to make it clear that there is no optical
difference between our No. 1 and No. 2 size Projec-
tion Lenses. The No. 2 size is merely a continuation
of the No. 1 size, providing longer focal lengths with
the same relative working aperture to maintain the
illuminating power but it is evident that in cor-
responding focal lengths the No. 2 size will transmit
more light than the smaller size, therefore, it is a
decided advantage to use the No. 2 lenses in any
focal length in which they are made from 5^4" up.
If the increased illumination is not needed on the
screen it can be saved in current so the lens of large
aperture is an economy to this extent.
To answer a question frequently put to us, we
state that the keystone effect incidental to projecting
the picture from an angle can not be corrected by
the Projection Lens, this being the natural result
of a difference in the length of the light rays from
the lens to the top and bottom or sides of the screen
as the case may be, causing a greater magnification
of the image at one point than at the other. Theatre
architects should be informed that the location of
the operating room should be planned to bring the
machines in a horizontal line with the center of the
screen.
136 MOTION PICTURE PROJECTION
In event that lenses we supply do not make the
picture close enough to the desired size, on account of
an error in measuring the distance, report at once
the exact width of the picture they produce and we
can then allow for the error and determine what the
distance actually is and the focal length required.
If you want Gundlach lenses to make a picture the
same size as it is made by some other lens send the
lens to us to be measured because you cannot depend
upon the focal length engraved on the mount.
Computing the Focal Length
The focal length required is ascertained by a
computation based upon the size of the opening in
the aperture plate, the size of the picture wanted
and the distance it is to be projected.
The distance is somewhat uncertain owing to er-
rors made in measuring it which we have known to
amount to as much as fifteen feet but in case a
mistake has been made by which lenses of the wrong
focus have been secured it is easily rectified. We
should then be informed the exact width of the picture
made by the lenses the customer has received and as
we have a record of their exact focus, we can calcu-
late from these two factors what the correct distance
is and determine the proper focal length of the lenses
to send in exchange. The distance of projection can
be obtained by referring to the architect's plans of
the theatre if these are available.
Measure the distance accurately, and you can de-
pend upon us to supply lenses of the correct focal
length.
MOTION PICTURE PROJECTION 187
Cleaning and Assembling
First note whether the extension tube is attached
to the front or rear end so you will replace it cor-
rectly. Clean both sides of the front combination but
do not remove it from the cell. To remove the re-
taining ring from the rear cell, press lightly on op-
posite sides of the ring with two fingers and unscrew
it. Too much pressure will make it bind so it will
not turn. Clean inside surfaces of the two lenses of
the rear combination and replace in the cell. Be
careful they are seated evenly, then screw up the
retaining ring just tight enough to prevent them
from moving, then clean the outside surface.
The rear lens is convex on both sides and the flatter
side is the outside rear surface. The retaining rings
should face towards the centre; reversing the cells
will disturb the correction.
To remove grease or oil from the surface of the
lens use a soft rag free from grit, moistened with a
little gasoline.
Be careful when screwing the parts together to
avoid skipping a thread and do not screw up any
joints very tight.
Do not use a hard sharp tool to remove the retain-
ing rings or it may slip and scratch the lenses.
138
MOTION PICTURE PROJECTION
LENS TABLE OF FILM PROJECTION
DISTANCE FROM FILM TO SCREEN
Stero.
M.P.
15
20
25
30 | 35
40
45
8
2
5.04
6.74
8.44
10.14
11.84
13.54
15.24
6.72
8.99
11.25
13.52
15.78
18.05
20.31
9
2J4
4.48
5.99
7.50
9.01
10.52
12.03
13.54
5.97
7.98
10.00
12.01
14.03
16.04
18.05
10
2 1 A
4.02
5.38
6.74
8.10
9.46
10.82
12.18
5.36
7.17
8.99
10.80
12.61
14.42
16.24
11
2#
3.65
4.89
6.12
7.36
8.59
9.83
11.06
4.87
6.52
8.17
9.18
11.46
13.11
14.76
12
3
3.34
4.47
5.61
6.74
7.87
9.00
10.14
4.46
5.97
7.48
8.99
10.50
12.01
13.52
13
3J4
3.08
4.13
5.17
6.22
7.26
8.31
9.35
4.11
5.50
6.90
8.19
9.69
11.08
12.48
14
sy.
2.86
3.83
4.80
5.77
6.74
7.72
8.69
3.81
5.10
6.40
7.69
8.99
10.28
11.58
15
3*4
2.66
3.57
4.47
5.38
6.28
7.19
8.10
3.55
4.76
5.97
7.17
8.38
9.59
10.80
16
4
2.49
3.34
4.19
5.04
5.98
6.74
7.59
3.32
4.45
5.59
6.72
7.85
8.98
10.12
17
4#
2.34
3.14
3.94
4.74
5.54
6.34
7.14
3.12
4.19
5.25
6.32
7.38
8.45
9.52
18
4#
2.21
2.97
3.72
4.48
5.23
5.99
6.74
2.95
3.96
4.96
5.97
6.98
7.98
8.99
19
4*4
2.09
2.81
3.52
4.24
4.95
5.67
6.38
2.79
3.74
4.70
5.65
6.61
7.56
8.51
20
5
1.98
2.66
3.34
4.02
4.70
5.38
6.06
2.64
3.55
4.45
5.36
6.27
7.17
8.08
21
5*4
1.89
2.54
3.18
3.8*
4.48
5.13
5.77
2.51
3.37
4.24
5.10
5.96
6.83
7.69
22
5*4
1.80
2.42
3.04
3.65
4.27
4.89
5.51
2.40
3.22
4.05
4.87
5.70
6.52
7.34
23
6#
1.72
2.31
2.90
3.49
4.08
4.67
5.27
2.29
3.08
3.87
4.65
5.44
6.23
7.02
24
6
1.64
2.21
2.77
3.34
3.91
4.47
5.04
2.19
2.95
3.70
4.46
5.21
5.97
6.72
25
654
1.57
2.11
2.66
3.20
3.75
4.29
4.83
2.10
2.82
3.55
4.27
5.00
5.72
6.45
26
6#
1.51
2.03
2.56
3.08
3.60
4.12
4.65
2.02
2.72
3.41
4.11
4.81
5.51
6.20
27
634
1.45
1.95
2.46
2.96
3.46
3.97
4.47
1.94
2.61
3.28
3.95
4.63
5.30
5.97
28
7
1.40
1.89
2.37
2.86
3.34
3.83
4.31
1.87
2.52
3.16
3.81
4.46
5.11
5.75
29
7*4
1.35
1.82
2.29
2.76
3.23
3.69
4.16
1.80
2.42
3.05
3.67
4.30
4.92
5.69
30
7'/4
1.30
1.75
2.21
2.66
3.11
3.57
4.02
1.74
2.34
2.95
3.55
4.16
4.76
5.37
81
7*4
1.26
1.70
2.14
2.58
3.01
3.45
3.89
1.68
2.26
2.85
3.43
4.02
4.60
5.19
82
8
1.22
1.64
2.07
2.49
2.92
3.34
3.77
1.62
2.19
2.75
3.32
3.89
4.45
5.02
83
8J4
1.18
1.59
2.00
2.42
2.83
3.24
3.65
1.57
2.12
2.67
3.22
3.77
4.32
4.87
34
8*4
1.14
1.54
1.94
2.34
2.74
3.14
3.54
1.52
2.05
2.59
3.12
3.65
4.19
4.72
85
8*4
1.11
1.50
1.88
2.27
2.66
3.05
3.43
1.48
2.00
2.51
3.03
3.55
4.06
4.58
MOTION PICTURE PROJECTION
139
LENS TABLE OF FILM PROJECTION Continued
DISTANCE FROM FILM TO SCREEN
Stero.
M.P.
60
56
60
64
70
76
80
1
8
2
16.93
18.97
20.33
21.69
23.73
25.77
27.13
22.58
25.30
27.11
28.92
31.64
34.46
36.17
9
254
15.05 ' 16.87
18.07
19.28
21.09
22.91
24.12
20.07
22.48
24.10
25.71
28.12
30.54
32.15
10
2y*
13.54
15.17
16.26
17.34
18.98
20.61
21.70
18.05
20.22
21.67
23.12
25.30
27.47
28.1)2
11
2#
12.30
13.78
14.77
15.76
17.24
18.73
19.72
16.40
18.38
19.70
21.01
22.99
24.97
26.2!)
12
3
11.27
12.63
13.54
14.44
15.80
17.16
18.07
15.03
16.85
18.05
19.26
21.07
22.89
24.10
13
354
10.40
11.65
12.49
13.33
14.58
15.84
16.67
13.87
15.54
16.66
17.77
19.45
21.12
22.23
14
354
9.66
10.82
11.60
12.38
13.54
14.71
15.48
12.87
14.43
15.46
16.50
18.05
19.60
20.64
15
sy 4
9.00
10.09
10.82
11.54
12.63
13.72
14.44
12.00
13.46
14.42
15.39
16.84
18.29
19.26
16
4
8.44
9.46
10.14
10.82
11.84
12.86
13.54
11.25
12.61
13.52
14.42
15.78
17.14
18.05
17
454
7.94
8.90
9.54
10.1? i 11.14
12.10
12.74
10.58
11.86
12.72
13.57 14.85
16.13
16.98
18
454
7.50
8.40
9.01
9.61 10.52
11.42
12.0:{
9.10
11.21
12.01
12.82 1 14.03
15.23
16.04
19
4&
7.10
7.96
8.53
9.10 9.96
10.82
11.39
9.47
10.61
11.38
12.14 13.28
14.43
15.1!)
20
5
6.74
7.55
8.10
8.64 9.46
10.27
10.82
8.98
10.07
10.80
11.52 12.62
13.70
14.42
21
654
6.42
7.20
7.72
8.23 9.01
9.79
10.30
8.55
9.59
10.28
10.97 12.00
13.04
13.73
22
554
6.13
6.87 ,
7.36
7.86 8.60
9.34
9.83
8.17
9.16
9.82
10.47 11.46
12.45
13.11
23
5*4
5.86
6.57
7.04
7.51 8.22
8.93
9.40
7.81
8.75
9.38
10.01 10.96
11.90
12.53
24
6
5.60
6.28
6.74
7.19 7.87
8.55
9.00
7.48
8.38
8.99
9.59 10.50
11.40
12.01
25
654
5.38
6.03
6.46
6.90 7.55
8.20
8.64
7.17
8.04
8.62
9.20 10.07
10.94
11.52
26
654
5.17
5.80
6.22
6.63 7.26
7.89
8.JH
6.90
7.74
8.39 ,
8.85 9.69
10.53
11.08
27
6tf
4.98
5.58
5.98
6.38 6.99
7.59
8.00
6.64
7.44
7.98
8.52 9.32
10.13
10.67
28
7
4.80
5.38
5.77
6.16 6.74
7.32
7.71
6.40
7.18
7.70
8.21 8.99
9.77
10.28
29
7^4
4.63
5.19
5.57
5.94 6.51
7.07
7.44
6.17
6.92
7.42
7.92 8.67
9.43
9.!K{
30
754
4.47
5.02
5.38
5.74 6.28
6.83 ,
7.1!)
5.97
6.69
7.18
7.66 8.39
9.11
9.5!)
31
734
4.33
4.86
5.21
5.56 6.08
6.61
6. SMI
5.77
6.48
6.95
7.42 8.12
8.82
9.2!)
32
8
4.19
4.70
5.04
5.38 5.89
6.40
6.74
5.58
6.26
6.72
7.17 7.85
8.53
8.98
33
854
4.06
4.56
4.89
5.22 5.71
6.21
6.54
5.41
6.07
6.51
6.95 7.61
8.27
8.7t
34
8}4
4.42
4.74
5.06 5.54
6.02 ,
6.34
5 25
5.89
6.32 ,
6.74" 7.38
8.02
8.44
35
8*4
3^82
4.29
4.60
4.91 5.38
5.84
6.15
5.10
5.72
6.13
5.65 7.17
7.79
8.20
140
MOTION PICTURE PROJECTION
LENS TABLE OF FILM PROJECTION Continued
DISTANCE FROM FILM TO SCREEN
Stero.
M.P.
84
90
96
100
104
110
116
8
2
28.49
30.53
32.57
33.93
35.29
37.33
39.36
37.99
40.71
43.42
45.24
47.05
49.77
52.49
9
2J4
25.32
27.14
28.95
30.16
31.37
23.18
34.99
33.76
36.18
38.60
40.21
41.82
44.24
46.55
10
2X
22.78
24.42
26.05
27.14
28.22
29.86
31.49
30.37
32.55
34.72
36.17
37.62
39.80
41.97
11
2Y 4
20.70
22.19
23.67
24.66
25.65
27.13
28.61
27.61
29.59
31.56
32.88
34.20
36.18
38.15
12
3
18.97
20.33
21.69
22.60
23.50
24.86
26.22
25.30
27.12
28.93
30.14
31.35
33.16
34.97
13
3J4
17.51
18.77
20.02
20.86
21.69
22.95
24.20
23.35
25.02
26.70
27.81
28.93
30.60
32.27
14
3J4
16.26
17.43
18.59
19.37
20.14
21.31
22.47
21.68
23.23
24.78
25.82
26.86
28.41
29.96
15
8#
15.17
16.25
17.34
18.07
18.79
19.88
20.97
20.22
21.67
23.12
24.09
25.06
26.51
27.96
10
4
14.22
15.24
16.25
16.93
17.61
18.63
19.65
18.95
20.31
21.67
22.58
23.48
24.84
26.20
17
4'4
13.38
14.34
15.30
15.94
16.57
16.52
18.48
17.83
19.11
20.39
21.25
22.10
23.38
24.66
18
4J4
12.63
13.54
14.44
15.05
15.65
16.56
17.47
16.85
18.05
19.26
20.07
20.87
22.08
23.29
19 ,
4^
11.96
12.82
13.68
14.25
14.83
15.86
16.54
15.96
17.10
18.24
19.10
19.77
20.92
22.06
20
6
11.36
12.28
12.99
13.54
14.08
14.89
15.71
15.15
16.23
17.32
18.05
18.77
19.86
20.95
21
5*4
10.82
11.60
12.38
12.89
13.41
14.19
14.96
14.42
15.46
16.49
17.18
17.87
18.91
19.94
22
6#
10.33
11.07
11.81
12.31
12.80
13.54
14.28
13.77
14.76
15.73
16.40
17.07
18.06
19.04
23
5H
9.88
10.59
11.29
11.77
12.24
12.95
13.66
13.16
14.11
15.06
15.69
16.32
17.26
18.21
24
6
9.46
10.14
10.82
11.27
11.72
12.40
13.08
12.61
13.52
14.42
15.03
15.63
16.54
17.45
25
654
9.07
9.73
10.38
10.81
11.25
11.90
12.55
2.10
12.97
13.84
14.42
15.00
15.87
16.74
26
&/,
8.72
9.35
9.98
10.40
10.82
11.44
12.07
11.64
12.48
13.31
13.87
14.43
15.27
16.10
27
6*4
8.40
9.00
9.60
10.01
10.41
11.02
11.62
11.20
12.01
12.81
13.35
13.89
14.69
15.50
28 ,
7
8.10
8.68
9.27
9.65
10.04
10.62
11.21
10.80
11.58
12.36
12.87
13.39
14.17
14.94
29
7J4
7.82
8.38
8.94
9.32
9.69
10.26
10.82
10.42
11.17
11.93
12.43
12.93
13.68
14.43
80
7*4
7.55
8.10
8.64
9.00
9.37
9.91
10.45
10.08
10.80
11.53
12.01
12.50
13.22
13.95
81
7*4
7.31
7.84
8.36
8.71
9.07
9.59
10.12
9.76
10.46
11.16
11.63
12.10
12.80
13.50
32
8
7.08
7.59
8.10
8.44
8.78
9.29
9.80
9.44
10.12
10.80
11.25
11.70
12.38
13.06
33
854
6.86
7.36
7.85
8.18
8.51
9.01
9.50
9.15
9.81
10.47
10.91
11.35
12.01
12.66
34
8J4
6.66
7.14
7.62
7.94
8.26
8.74
9.22
8.88
9.52
10.16
10.58
11.01
11.65
12.29
85
8*4
6.46
6.93
7.40
7.71
8.02
8.48
8.95
8.62
9.24
9.86
10.27
10.6
11.31
11.93
i
1
MOTION PICTURE PROJECTION 141
THREE COMBINATION LENS
There is now on the market a three combination
lens, known as the Keen-o-lite three combination lens ;
it is so constructed that the rear objective lens is
never more than two inches from the aperture plate,
thus giving an increased light illumination on the
screen, after allowing for the additional reflection
and absor'tion loss due to the extra third combina-
tion. Below is the report of Professor Weinrich of
Columbia University who lately made some compar-
ative tests with the lens.
Report of Professor Weinrich of Columbia University.
I herewith submit report oh my comparative test of a
KEEN-O-LITE and a lens of another make, both of six and
three quarters inch -focal length.
The primary object of the test was to compare the illumina-
tion produced upon the screen by the Keen-o-lite Lens and
another projection lens of high standing and the same focal
length, the same light flux passing through the frame-plate in
both cases.
As the design of the "Keen-o-lite" lens is based upon the
actual conditions as they exist in the modern projection ma-
chine it may be well to first consider these conditions from a
somewhat theoretical point of view.
The most practical way of adjusting the arc, condensers and
frame-plate of a projection machine is such as to produce an
enlarged image of the positive crater, a little larger than the
aperture, upon the frame-plate. In order that the picture be
as uniformly illuminated and spotless as possible, Jt is best to
have the most concentrated part of the beam and the sharpest
image of the crater a short distance from the frame-plate, on
the condenser side; i. e., have a slightly extra focal image
thrown upon the aperture. This adjustment naturally pro-
duces a diverging beam through the aperture of the frame-
plate. In order to utilize as much as possible of this diverging
beam we either have to allow the light to fall upon a compara-
tively small lens placed near the aperture or a comparatively
large one a" greater distance away. In the design of the Keen-
142 MOTION PICTURE PROJECTION
o-lite lens the former of these two methods was adopted and
skilfully executed. The "back focus" of the ordinary type of
6% -inch lens is about 6 inches while in the case of the Keen-
o-lite it is only a little more than one-third as much, and the
clear aperture of the back lens is only slightly smaller than
that of the other. The entering beam in the case of the "Keen-
o-lite" is therefore very considerably larger, and with it the
total brightness of the picture as was verified by test.
There are, however, two further advantages of the Keen-o-
Hte lens which are even more important than the foregoing.
They are: a more uniformly illuminated picture, from center to
edge or corner, and better definition.
The rays which the ordinary lens does not utilize are to a
much greater exTent from the edges and corners of the film
than from the central part and therefore would increase the
illumination of these parts of the picture relatively to the
center, thereby producing a more uniform illumination over
the entire surface of the screen.
The definition given by a lens can in general be made more
perfect by the addition of more elements and curved surfaces.
The addition of the extra element of the Keen-o-lite has pro-
duced a lens of very decidedly better definition than any other.
The figures hereinafter given were obtained with a set-up
like that of the average machines using 6^ -in., 7^-in. con-
densers. The source was brightly illuminated opal glass
bounded by a ^-in. circular aperture in imitation of the posi-
tive crater. The position of source condensers and frame-
plate were absolutely the same during all tests and the bright-
ness of the source invariable. The conditions were hence the
same as in the projection machine itself but their invariability
made the test much more dependable than if an arc had been
used. The results of the test were as follows:
Keen-o-lite gave 12.5% more light at center of screen.
Keen-o-lite gave 82.5% more light half way out to corner.
Keen-o-lite gave 63.0% more light at corners.
Integrating these results we find that the total illumination
of the screen is about 32.8% greater in the case of the Keen-
o-lite lens over the lens of another make.
The definition given by the Keen-o-lite ' is also decidedly
superior.
MOTION PICTURE PROJECTION 148
ROBIN CINEMA ELECTRIC TIME SYSTEM
This system, invented by J. E. Robin in 1914, is
what the name implies, a system to provide an ac-
curate and predetermined running schedule for mo-
tion picture and synchronizing the music with same.
It is an electrical speed indicating device, con-
sisting of a small extremely accurate direct current
generator attached to the projection machines and
connected to a very sensitive meter by cable. The
meter is calibrated with the generator and shows in
feet per minute and the rate of time per thousand
feet at which the film is being operated. In operation
the voltage generated varies with the speed of the
machine causing a corresponding increase or decrease
of the connected meters.
Plate No. 1 shows a single unit consisting of a
generator, meter and cable for a single machine.
PLATE 1
Generator and Meter, Single Unit
144
MOTION PICTURE PROJECTION
PLATE 4
Robin Speed Indicator Attached to Simplex Projector
MOTION PICTURE PROJECTION 14-5
Plate No. 2 shows an equipment for two projection
machines with switchboard and two meters.
PLATE 2
Robin Indicator for Two Machines with Two Indicators
Plate No. 4 shows Robin speed indicators with
switchboard as attached to a Simplex machine.
146
MOTION PICTURE PROJECTION
Plate No. 3 as attached to Powers projector.
PLATE 3
Robin Speed Indicator Attached on Powers Machine
MOTION PICTURE PROJECTION
147
The meters and generators are made of the best
materials throughout and are carefully tested prior
to leaving the factory and the operator should ex-
perience no trouble whatsoever in maintaining the
same.
The generators are ballbearing and contain suf-
ficient grease to last for a year and therefore re-
quire practically no attention whatsoever.
In ordering speed indicators it is necessary to
specify the make and type of the projection ma-
Robin Signal Telegraph With Eight Synchronized Meters as
Installed in New York Capitol
148 MOTION PICTURE PROJECTION
chines, the diameter of the shutter shaft and the dis-
tance for the cable required. Where it is desired to
use a meter in the orchestra pit, the distance be-
tween the two projection machines and the orchestra
pit, measured on one side of the circuit, should be
given.
In the majority of the larger theatres it is custom-
ary for the director to be present in the reviewing
room at the time the rehearsal is made. Then the
proper length of the performance is predetermined
and the running speed noted, and the musical direc-
tor arranges his music accordingly.
With the operating speed predetermined the oper-
ator starts his machine and regulates the speed of
the projection machines in the regular way by the
motor attachment until the indicator shows the cor-
rect speed in feet per minute, and in this manner
the music and the projection speed is synchronized
and the duration of the performance will be the same
at each showing.
In use in the majority of leading theatres through-
out the country where it has proved the value and
necessity of projecting pictures at the relative speed
as taken, with music synchronized to support the
action of the photoplay.
MOTION PICTURE PROJECTION
149
Plate No. 5, illustrates switchboard and connec-
tion for equipment of two projection machines, two
meters in the booth and one for the orchestra pit.
ROBIN ELECTRIC TIME SYSTEM
PLATE 5
RI6HT MACH INOOTOR
1-niitr SWITCH
StflTCH BCMRD
//Die }0 HOT CMfHtt CAtLC LCN
KfBIHS ClMfMA [UCTItlC TIME
DICATORS Wff^ftO GENERATORS
ATf Sc* i rrre \
C4SLC JOKTH l*rt fit CAC/ftlWC*
Two Machines, Three Meters and Switchboard
150
MOTION PICTURE PROJECTION
Plate No. 6 illustrates correct position for instru-
ments with meter underneath the lookout holes and
which gives the measurements of both and drilling
template. PLATE 6
PPOJICTICN
FUr
0PCMIN*
LOCATION or Mere*
'jK. N T T e i!Ytt L
#/
5llt
tlMTH
HIP
y?H
HOLLOW TILE
TOGGLE
^"
J"
CEMENT
EXPANSION
BRICK
"
XSBESTOSj
HtX HMD
(V
%a
SHEET IRON
-
5L-4TE.WNEUS
HEX CAP
2"
OS SPRING WASHERS BETWfCNMfTCI
B*ACKET AND NUTS
J E.ROBIN
Robin Speed Indicator
MOTION PICTURE PROJECTION 151
'A Pocket Reference Book
FOR
Managers and Projectionists 1
By JAMES R. CAMERON
Price One Dollar
THEATRE SUPPLY COMPANY
124 WEST 45TH STREET NEW YORK CITY
152
MOTION PICTURE PROJECTION
PORTABLE PROJECTORS
The portable projector has made a permanent
place for itself in the motion-picture industry, several
hundreds of this class of machine are in daily use in
studios, cutting-rooms and viewing rooms, salesmen
are using them to help sell their wares. Motion pic-
tures are becoming a part of the curriculum in
churches and schools through the medium of the port-
able projector. This type of machine has been
brought to a high stage of perfection, it is now pos-
sible to get a complete motor-driven motion-picture
machine enclosed in a carrying case measuring ap-
proximately 18"xl7"x8" and weighing about 25 Ibs,
and this compactness has not been obtained by sacri-
ficing accuracy. Portable projectors are built along
various lines, each manufacturer having his own ideas
toose LOOP
o HOTHAve am
TOUCH MAHAIIHf
MOTION PICTURE PROJECTION
153
No. 1
Focusing button
No. 2
Framing button
No. 3
Lamp switch
No. 4^
P. Projector
R. Rewind
No. 6
Cord connection.
No. 7
P. Projector.
R. Rewind.
N. Neutral
No. 5
Motor speed
control
154
MOTION PICTURE PROJECTION
on this subject, and to attempt to describe each type
in a work of this kind would prove to be a hopeless
task, we will however devote a little space to the
handy suitcase model.
THE ACME PORTABLE PROJECTOR
To those who are at all familiar with Moving-
Picture Projectors, a glance at the accompanying
The Safety Shutter (B) drops and covers the aperture plate
opening, cutting off the light rays, whenever the Acme is not
being operated. While the machine is being operated the
Shutter is held by centrifugal force in position shown by
dotted lines "A." In threading the film, the "pull-out" (D) is
opened into position C, thus allowing the greatest accessibility
in getting the film in place. But as soon as the film is threaded
this "pun-out" slips back into place and is held there by a coil
spring, preventing any of the film from ever getting in the
path of the light.
MOTION" PICTURE PROJECTION
155
diagrams will be all the instruction required. To the
uninitiated, however, a word or two of explanation
may be of advantage.
Upon examining the film you will find that one
side has a very dull finish. This is called the emulsion
side. The other side, which has a glossy surface, is
known as the celluloid side. The film, when properly
rewound, must have the emulsion side upward.
When threading the projector, the film, when
placed in the aperture plate, must be inverted that
is, show the image "upside down" and with the dull
or emulsion side toward the lamp house.
To thread the Acme pull out the round film guard
between the gate marked No. 4 and the lens, push down
the three guide rollers numbered 3,6 and 7 in diagram
Inside (in roller.
Inside or Takeup
156 MOTION PICTURE PROJECTION
"B" these are shown in diagram "C" in open position.
Next open aperture gate by lifting spring catch on
gate number 4 towards you, this is done through the
small round hole in the division plate between the
lamp house and projector. Next open the magazine
by pushing down on the catch, swinging the outer
half outwards so that the magazine when open hangs
at right angles from the projector, then place the
full reel of film on the shaft of the outer magazine,
turn clip on this shaft down to keep reel in place.
Next draw the film through the rollers and pull tow-
ards you. The emulsion or dull side must be face
upward, and three feet of film should be drawn from
the outer magazine in order to thread the Acme, then
partly close the outside magazine, place the film over
the top of stationery guide roller No. 1, under film
sprocket marked No. 2 making sure that the per-
forations are over the teeth of this sprocket, then
push up guide roller No. 3 into place; the film is
in correct position when it is between sprocket No. 2
and roller No. 3 as shown in diagram "B." Now
make a loose loop that is also shown in diagram "B"
placing the film in the aperture plate marked No. 4,
close aperture gate and see that the spring catch on
it is securely fastened. When the film is placed in the
aperture plate correctly the picture must be upside
down with the emulsion or dull side towards the
lamp house. The film must now pass in front of
sprocket No. 5 as shown in diagram "B." The perfo-
rations must be engaged on the teeth of the sprock-
et. When this is done push guide roller No. 6 into
position as shown in diagram "B." This same dia-
gram shows a loose loop between sprocket No. 5 and
MOTION PICTURE PROJECTION 157
If desired you can change the lamp in the Acme in a few
seconds merely slide it out of its housing, as shown in the
illustration. Both up-and-down and horizontal adjustments
are made by simply loosening the screws, getting the adjust-
ment you want, then tightening them again. The Condenser,
in case it needs cleaning, is easily removable by merely loosen-
ing the two thumb-screws.
158 MOTION PICTURE PROJECTION
sprocket No. 8 ; this is imperative. This loop
must be as large as it can be made without touching
the round magazine underneath it. Place the film
underneath the guide roller No. 7 and over the top
of sprocket No. 8. When this is done close guide
roller No. 7; now you have the projector mechanism
threaded open the outer magazine, which can be
done while the film is in it. Place film from sprocket
No. 8 through the slot of the inner magazine between
the magazine rollers. Take the end of film ; place it
underneath the spring clip on the center of the empty
reel hub, give it one turn to securely fasten the film,
place this reel on the inner magazine shaft, be sure
that the slot in this reel slides over the key on this
shaft. When in position turn down clip on the end
of shaft to hold this reel in place. The direction of
travel on this inner reel is always towards the right.
Then close outer magazine, machine is now ready for
operation.
To operate, insert connection plug in opening
No. 6 at back of case. See that indicator on bottom
No. 4 points to "P," (Picture) ; also that lever No. 7
is at "P."
Push in the button on switch No. 3. This lights
the lamp. Then turn button No. 5 slowly to right.
This operates the motor and any speed desired may
be obtained by merely turning it. To stop machine
turn back to left.
Button No. 1, on top of the projector, operates
the focusing device, and if you cannot get the image
sharp by turning this button, open the case door and
adjust the lens tube in the lens jacket by moving it
forward or backward with your hand until the right
effect is obtained.
MOTION PICTURE PROJECTION 159
The simple button (on outside of case) moves the rheostat up
and down, as shown by the dotted line in the illustration, thus
giving practically any speed required.
160 MOTION PICTURE PROJECTION
Button No. 2 operates the framing device, and by
turning in either direction it enables you to frame
the picture instantly. If you do not see the full pic-
ture on the screen, simply operate button No. 2 to
locate correctly.
To rewind after using, be sure light is turned off;
take off the full reel from inner magazine shaft. Re-
move empty reel from outer magazine. Stand full
reel on rim, with end of film toward the right. Now
wind end on hub of empty reel, dull side outward,
securing end firmly with a few turns. Now place
empty reel on inner magazine shaft, slipping film
through magazine rollers. Loop film over the two
wooden rollers in top of case as shown in Fig. "C."
Turn down clip on inner shaft holding the reel in
MOTION PICTURE PROJECTION
161
When the reel has been run through the Projector (and must
be re-wound to be run again), you merely transfer the reels
on the feed and takeoff shafts, run the film over the two
wooden rollers, and turn the button releasing the motor. None
of the projecting mechanism is used for this purpose, but re-
mains at a standstill during the rewinding operation.
162
MOTION PICTURE PROJECTION
place. Bring outer magazine around to closing posi-
tion, threading film through magazine rollers, placing
reel on shaft, again turning down clip on shaft to
hold reel in place. Close and lock outer magazine.
At back of case, turn indicator on button No. 4* to
"R." - Rewind. Turn also lever No. 7 to "R."-
Rewind. Then turn button No. 5 to right slowly
to operate motor for rewinding.
The lens barrel is easily taken out through the front opening
without having to remove shutter or any other part. This lens
barrel merely slides into the lens jacket (A), and this jacket
is moved forward or backward (in B) by the button on top
of case. Correct focus for any distance may be obtained by
sliding the lens either way within this jacket.
MOTION PICTURE PROJECTION
163
Focusing Button
Framing
Button
Oil Tube ,
Cover
Clutch
Rear View of Acme Showing Adjustments and Controls
164 MOTION PICTURE PROJECTION
Caution
When through rewinding, always turn the indicat-
ors on buttons No. 4 and No. 7 to the letter "P"
Picture before making ready for the next pro-
jection.
OPERATING BY HAND
To operate the Acme Projector by hand, all that
is necessary is to move the lever No. 7 to the center
groove which releases the motor.
OILING THE PROJECTOR
On the top" of the machine case you will notice a
small oblong opening that has a metal slide door,
push back this slide and you will find four oil tubes
directly underneath it. These four tubes lubricate
the bearings in the back of the mechanism. The
motor has an oil tube coming through the perforated
guard that leads to its inner bearing. The top of
the fan has a drilled screw this is for oiling. On
the end of the fan bracket you will notice two fibre
pulleys. Between these two you will find an oil hole
which lubricates them. There is an oil well on the
outer end of the motor which is very accessable.
The inside of the two shafts in the magazine must
have oil you will find oil holes there for same. On
the mechanism you will find on the shutter shaft two
nickel plated brackets with holes for lubricating.
You will find oil holes on Shaft bearings of feed and
take-up sprockets the intermittent sprocket has a
bronze bushing with oil hole in same, to get at this,
slide the mechanism forward as far as it will go. On
side of case opposite door in about the center close
to the bottom is a round hard rubber bushing, you
MOTION PICTURE PROJECTION
165
SLIDING COVER"
On top of the case is a sliding cover, just beneath which are
five oil-tubes, each leading directly to an oil-hole at some bear-
ing. The motor shaft and belt pulleys are also provided with
similar oil-tubes. The intermittent mechanism is of the Geneva
type and runs in an oil bath. The Acme intermittent move-
ment can be adjusted without having to remove the mechanism
from the case.
1G6
MOTION PICTURE PROJECTION
will find the shaft for double idler pulley right inside
this hole; this must have oil very often, in fact all
bearings should have a drop of oil each day before
operating machine.
,
Merely turning the button on top of the case in either direction
frames the picture instantly. The illustration shows that, in
framing, the aperture plate and lens remain absolutely sta-
tionary the movement, forward or backward, of the mechan-
ism adjusts the relative position of the picture until it
"frames" correctly.
MOTION PICTURE PROJECTION 167
THE VENTILATING, HEATING AND COOL-
ING OF THEATRES
Rapid as has been the development of the motion-
picture theatre, in one department there has been
but little visible progress ventilation.
We therefor approached the Monsoon Cooling
System of New York City who are experts on this
subject, and they were pleased to have their chief
engineer Mr. E. L. Garfield co-operate with us in
the preparation of a technical article on the subject
of theatre ventilation.
Some blame attaches to the exhibitor because of
the scant attention he has given to this important
subject. But the underlying cause, to my mind, is
the general lack of specialized knowledge on theatre
ventilation.
Winter ventilation, for instance, is almost univer-
sally treated with absolute disregard for its effect on
the heating. The natural result is a house warm
enough, but ill-smelling and stuffy; or a house with
a pure atmosphere, but a bit too chilly for comfort.
The usual treatment of summer ventilation and
cooling leaves out of consideration the high percent-
age of moisture, humidity, to be found in the at-
mosphere in hot weather. And yet this humidity
causes more discomfort in a warm theatre than the
high temperature itself.
Let us first consider the proper method of venti-
lating a theatre in cold weather. It must be recog-
nized from the outset that this is impossible without
168
MOTION PICTURE PROJECTION
the loss of some heat. How great this heat loss is
depends on :
1. The frequency of air change.
2. The degree of scientific skill applied to the
problem.
The two generally accepted methods of heating
and ventilating a theatre may be classified as follows :
1. All direct radiation for heat, with exhaust
fans for ventilation.
2. Indirect radiation or warmed air supply for
both heating and ventilation, combined with a
small amount of direct radiation.
Direct radiation comprises the use of the ordinary
steam or water radiators, the heat being applied
directly to the air in the immediate vicinity of each
radiator.
Indirect radiation (or tempered air supply) con-
sists of warming fresh air and forcing it into the
auditorium at one or more points.
Monsoon Cooling Apparatus. The Arrows Show How the Air
Currents Reach Every Point of the Auditorium
MOTION PICTURE PROJECTION 169
Mainly for reasons of economy, I would use the
first method outlined above for the smaller theatre
say, one up to 800 seats. It is simple and practical.
With sufficient radiation, properly distributed, there
can be no great difficulty in maintaining a fairly
even temperature.
Successfully to combine this method of heating
with good ventilation demands careful study so as
to effect the proper air change with minimum heat
loss, and without objectionable drafts. I have little
regard for exhausting at the ceiling line because it
assumes that the warm air at the ceiling is necessari-
ly foul air.
This is wrong: foul air is heavy. It has been
breathed and become laden with moisture, carbon
dioxide and organic impurities thrown off by the
lungs. Naturally, being heavy, it lies close to the
floor line; and because it lies near the floor line,
it is at this point that we must exhaust if we would
remove';tfe*foul, ill-smelling air.
Furthermore, this heavy air does not readily ab-
sorb heat. It is therefore the coldest air in the
house; and if we exhaust it we pass out with it the
smallest possible amount of heat. Consequently,
from the standpoint of heat economy, it costs least
to remove this air, while it costs most to remove
air at the ceiling line.
With these facts established, it is obvious that the
air should be exhausted at the floor line near the
stage, or at the end opposite from the entrance doors.
The fan apparatus should effect a complete air
change within a certain limited period, to be decided
on by a competent ventilating engineer. Such an
170 MOTION PICTURE PROJECTION
air change, calculated on ordinary winter temper-
atures, might prove too frequent during a few un-
usually cold periods. The thing to do then is to cut
down the air change slightly, in the interests of heat
economy by reducing the speed of the fan.
The only possible objection to this method of
heating and ventilating is the possible slight tendency
to drafts through the doors, but this can be compen-
sated for by placing extra radiation at the entrances.
Heating and ventilating in this manner will pro-
duce fairly satisfactory results, and its cost is not
out of proportion to the cost of the average house
of 800 seats. It could not be improved upon except
by the use of indirect heating, usually too expensive
for the small theatre.
In the larger house the cost of indirect heating
does not loom up so large in proportion to the cost
of the complete building. In fact, the cost may prove
in most cases to be less that that of diroct heating.
And, certainly, in view of the splendid results, the
indirect method is far more desirable.
In laying out an indirect heating aiid ventilating
system for the larger house, warm air supply units
are located at the stage end (opposite from the en-
trance doors). These supply the required amount
of fresh air at a temperature of 70 or over. It
is imperative that large fans be used, so that the
apparatus can be run at low speed, handling the air
at low velocity, thus insuring absence of drafts, of
noise and of vibration.
The fresh air supply is taken at least 20 feet above
ground level, so that it is pure and free from dust.
In this way, we eliminate the necessity for an air-
MOTION PICTURE PROJECTION 171
washer, which is expensive, requires constant atten-
tion and is objectionable for other reasons. The
roof or the attic is usually the best location for the
heating and ventilating equipments.
The air blown into the theatre finds its way out
through openings at the floor line but, to insure
positive circulation, exhaust fans are sometimes ad-
visable. A large part of the air supplied naturally
passes out through the entrance doors and also
through openings in the rear of the balcony, if there
is one. The fundamental principle is to keep re-
moving the air from the floor line or breathing zone,
and to allow the warm, fresh air blown in to settle
like a blanket of warmth evenly over the entire audi-
torium.
Two desirable advantages that appeal instantly to
the theatre manager are these:
1. No inrush of cold air from outdoors when the
entrance doors are open. On the contrary, an
outward motion of warmed air, due to slight
pressure maintained by heating fans.
2. House heated very rapidly before opening, as
theatre air can be passed and re-passed several
times through heaters (re-circulated).
Such a system is all that is required during the
time that the auditorium is occupied by the audience.
However, it would be well to provide some direct
radiation to allow for heat losses through exposed
walls, although the heat radiated by persons in the
audience will, in a large measure, compensate for this
particular heat loss.
This small amount of direct radiation is also of
good use at times overnight, particularly when
172
MOTION PICTURE PROJECTION
the temperature falls below freezing point, with dan-
ger to water pipes, etc. For this we need just enough
direct radiation to keep the temperature at 35 F,
as it is not economical to run the fans for heating
when the theatre is not occupied and ventilation is
not required. The dressing-rooms, toilets, rest-
rooms, etc., have the usual direct radiation.
Extremely cold weather that falls below normal is
unusual and generally of short duration. For this
reason, it is not a great hardship to sacrifice a small
part of our fresh air supply for fuel economy, par-
ticularly as the system is designed for maximum fresh
air supply and therefore permits of some reduction.
During these periods some of the warm air already
blown into the theatre is brought back to the heating
units and mixed with fresh, outdoor air. By the use
of an arrangement of dampers, it is possible to ob-
tain a mixture of fresh air and re-circulated air in
proportion to meet any unusual drop in temperature.
This feature is utilized only during the few short
periods of extreme cold.
Monsoon Cooling Apparatus Installed in Large Theatre
MOTION PICTURE PROJECTION 173
When absolutely perfect results are desired and
finances permit a profitable investment is a system
of thermostatic control of mixing dampers, a thermo-
static control of steam valves, or a combination of
both. With this system the lower the temperature,
the greater the quantity of theatre air re-circulated
and mixed with fresh air. On the other hand, a rise
in temperature is accompanied by an automatic shut-
ting off of steam in part of the indirect heaters, so
reducing the temperature of the fresh air supply.*
And now summer ventilation and cooling. At this
season of the year an enormous quantity of moisture
is thrown off by the human body, and the problem
then becomes one of removing the air in such volume
as to remove with it this moisture as rapidly as it is
formed.
Actually, there is no binding necessity to lower the
temperature. The point at issue is to make the
human body comfortable, and this can easily be done
by creating a breeze, passing it over and around
every person in the audience and carrying away the
bodily heat and, especially, evaporating the moisture
constantly forming on the skin. It is simply taking
advantage of an old principle, the practical working
efficiency of which is convincingly demonstrated every
time a perspiring person takes a trolley or auto-
mobile ride on a hot day. It's the breeze that cools.
It can be nothing else, since the temperature is no
lower.
The cost of cooling by the breeze method is very
small in comparison with the lower temperature
method. All that is necessary is sufficient fan capac-
ity to effect a very rapid air change from ten to
174 MOTION PICTURE PROJECTION
fifteen times that required for winter ventilation.
It will be found that this is sufficient to create a
perceptible movement of air that will prove entirely
satisfactory. It may be honestly advertised as a
"cooling system" and can be depended upon to keep
the house comfortable in the hottest summer weather.
As with the winter ventilation, best results can be
expected only if the "cooling system" is laid out by
a competent engineer who has had practical experi-
ence in this line of work. Unless this precaution is
taken, there can be no safe assurance that the air
currents are evenly distributed over the house
that the breezes can be felt throughout, that they
are not too strong in some quarters as to be ob-
jectionable.
It is equally important that a fan apparatus be
specified designed specially for moving tremendous
volumes of air at low velocity and operating slowly
enough to be silent.
An economical arrangement, for a theatre under
construction is to arrange the fan apparatus so that
part of the cooling and ventilating fans are used
with the indirect heaters to form the heating and
ventilating units for winter operation. Or, stated
the other way, the fans used in the heating and venti-
lating units may also be used for cooling in summer,
in combination with auxiliary cooling equipment to
give the additional air volume required in hot
weather.
The cooling and ventilating system alone, without
heating, can be installed in any theatre, no matter
how old, at any time.
MOTION PICTURE PROJECTION 175
Ventilation of theatres is now receiving more atten-
tion than ever. And the time is coming soon, too-
when the problem of ventilating will receive fully as
much attention as any other connected with the de-
signing and building of theatres.
Hot weather cooling, too, will receive more con-
sideration. And why not? If it is profitable to
heat a theatre in winter to attract or keep business,
why not cool the house in summer for the same
reason?
As the importance of these subjects is better ap-
preciated, it will be realized more and more that they,
should be handled, not by hit-or-miss guesswork, but
by competent engineers who know by scientific train-
ing and experience what is needed and how to pro-
vide it.
176 MOTION PICTURE PROJECTION
Accessories and Profits
Inter-Ocean Film Corporation is the oldest
film accessory company in the world.
What does this mean? It means protec-
tion for the buyer inasmuch as no accessory
organization could stay in business which was
not supplying its vast army of customers
with the right accessories at the right price.
Inter-Ocean's whole success has been
founded on its ability to deliver a quality
product at a reasonable price. Inter-Ocean
Film Corporation has been prospering be-
cause it has been serving.
Let Inter-Ocean serve you. A complete
line of high quality accessory products are
available at the Inter-Ocean offices.
ACCESSORY DEPARTMENT
INTER-OCEAN FILM CORPORATION
218 West 42nd Street
New York City
MOTION PICTURE PROJECTION ITT
Accessories and Profits
There are no projector carbons like Speer
Carbons. Nor is there a better projector
than the Master Projector. The Fulco line
of over three hundred standard articles is
unparalleled. Wohl Studio Equipment fur-
nishes a striking example of economical and
practical studio accessories. In addition to
the above-named accessory products, Inter-
Ocean's list of products includes the well-
known Hawk Spotlight, Argus products and
Westinghouse incandescent lamps.
Inter-Ocean invites correspondence from
prospective buyers of motion picture acces-
sory products.
ACCESSORY DEPARTMENT
INTER-OCEAN FILM CORPORATION
218 West 42nd Street
New York City
178 MOTION PICTURE PROJECTION
AUTOMATIC ARC CONTROLS
The hand-fed arc is fast losing favor, most thea-
tres are now equipping their projectors with arc con-
trols. There are various makes of arc controls on
the market, but as it has been the lot of the writer
to have seen the Peerless automatic controller under
various stages of manufacture and to have been in
close touch with them under actual working con-
ditions in various Broadway theatres we shall take
the liberty of discussing this special type in these
pages.
This Control is made for use on all makes of pro-
jectors having Direct Current at the arc, and will
operate equally well with current supplied by a
Motor Generator, Converter, Mercury Arc Rectifier
or 110 volt D.C. from the power companies.
The instrument is designed to stand on the floor
at the rear of the projector, the power being trans-
Peerless Automatic Arc Control Before Assembling
MOTION PICTURE PROJECTION 179
mitted from the motor mounted on the Control to
the feed handle of the arc lamp by means of a tele-
scoping tube and shaft that automatically adjusts
itself- for the various height projectors.
A complete feed handle assembly shown in the
accompanying line drawing, consisting of the parts
M, J, N, F, P with a worm gear and worm mounted
thereon is supplied as a part of the Peerless Control,
and replacing the regular feed rod and handle on the
projector.
The actuating element is completely enclosed and
the entire device is approved by the Underwriters
Laboratories Inc., their approval number E-4988.
The operation of the Control is governed by
changes in the arc voltage there being two highly
sensitive magnets in series with each other connected
directly across the line in multiple with the arc and
their strength varies directly proportionate to the
variation in the arc voltage. These magnets influence
an armature carrying contact points having a gap
of approximately ".006", and to the armature is
connected a spring which in turn is attached to the
adjusting screw marked "A" on the accompanying
line cut. The various length arcs may be obtained
by screwing in or out this adjusting screw.
These contacts open and close a circuit to the
special wound series type motor. It will be readily
seen that when the attraction of the magnet exceeds
the opposite pull on the spring attached at the end
of the screw "A" that the armature will move toward
the magnet and the circuit close with the result that
the motor rotates and feeds the carbons together un-
til the arc voltage has decreased and in turn the
180 MOTION PICTURE PROJECTION
magnetic strength of the magnets decreased to a
point where the spring is the stronger, with the
result that the circuit is opened.
Due to the type of construction employed in the
manufacture of this element, a degree of sensitiveness
of less than 1/5 of one volt is obtained, that is to
say, that an increase in the arc voltage of less than
1/5 of one volt above the point for which the ad-
justment is set will close the circuit. Thus securing
a delicacy and fineness of operation that is truly re-
markable.
Showing the Arc Controls Connected to Projector Arc Lamp
MOTION PICTURE PROJECTION 181
A gear reduction through two sets of worm gears
one on the Control itself and the other on the feed
handle provides a gear ratio of 6400 to one, with
the result that the movement of the carbons can
scarcely be detected with the naked eye, and insures
against any disturbances on the arc crater, as would
be the case where they moved rapidly such as is so
often the practice with the hand-fed arc.
A high resistance unit is connected in series with
the motor, permitting some current to enter the
motor at all times when the knife switch of the pro-
jector is closed. This resistance serves the purpose
of reducing to a minimum the load which the circuit
breaker has to break and acts as a discharge coil as
well, thus eliminating any destructive spark.
The automatic arc controls have been on the
market long enough to have their general merit well
proven and taken altogether are highly recommended
for use in theatres desiring high grade screen results.
INSTRUCTIONS FOR INSTALLING AND
OPERATING THE PEERLESS AUTO-
MATIC ARC FEED
This control is made for use on projectors using
Direct Current at the arc only.
Carefully unpack the control from the box con-
taining it, and remove all parts. Place the instru-
ment on the floor directly beneath the arc feed
handle. Attach the nickle-plated tube (shown as
"B" on the blue print) to the gear shaft universal
joint by means of the screw and nut furnished, and
insert the shaft "G" into the tube.
182
MOTION PICTURE PROJECTION
If the arc control is to be used on a Powers, Motio-
graph or Type "S" Simplex arc lamp, remove the
arc feed handle and rod and replace with the comp-
lete assembly furnished with the control same as it
is received.
If the control is to be used with the "regular"
type Simplex arc lamp, having the feed rod rigidly
attached to the arc lamp, it is only necessary to
remove the Simplex fibre handle and in its place as-
semble the parts shown as "N", "J", "M" and the
gears, collars, etc. onto the Simplex rod.
MOTION PICTURE PROJECTION 183
Drill a small hole in the rear of the lamp house,
about five inches below the opening for the arc feed
rod and insert the anchor "F", or attach anchor to
one of the adjusting rods by means of clips furnished.
Attach the universal joint at the end of the rod
"G" to the shaft "H" on the feed handle.
The control is then ready for the electrical con-
nections. Bear in mind that the Peerless control is
a voltage-governed device and is actuated by changes
in voltage at the arc, caused by the increase in the
arc gap due to the consuming of the carbons. It is
necessary, therefore, that the device be connected in
multiple with the arc, and at a place in the lamp
circuit where it will receive current after it has pas-
sed through the rheostat or motor-generator, as
shown on the blue print.
Attach a snap switch and a fuse block, shown as
"K" and "L" on the print, at a convenient place at
the rear of the projector, a good place being at the
side of the arc lamp knife switch box, as illustrated.
Encase the wires "C" and "D" in flexible Greenfield
conduit "O" and run to the switch and make con-
nections. From the switch "K" run wires to inside of
knife switch "R" cabinet and connect to each of the
arc feed wires as shown, being sure that the current
which will enter the control at this point, has al-
ready passed through the rheostat or motor-gener-
ator.
See that the snap switch "K" is "off" and strike
the arc and allow it to burn until the crater has
properly formed on the carbons. Bring the carbons
together to the arc gap which you wish maintained,
turn on the switch and loosen knurled clamping screw
184 MOTION PICTURE PROJECTION
"J" on the feed handle. If the motor runs when the
carbons are at the gap desired, slowly screw out the
arc gap adjusting screw "A" until the motor stops.
Any arc gap desired may then be obtained by screw-
ing in or out the screw "A", in, to shorten the gap
and out, to lengthen it. The control will automatic-
ally maintain the arc gap for which screw "A" is
set, and further adjustment of it is not needed and
its position should not be changed.
When putting a new trim of carbons in the lamp,
allow them to burn in before turning on the snap
switch "K", as the voltage at the arc is much lower
than normally until craters have formed, which would
result in the control failing to feed until the craters
had formed and the voltage raised to normal at the
desired gap.
MOTION PICTURE PROJECTION
185
POWER'S TYP"E LAMPHOUSE AND LAMP
The Nicholas Power Company have incorporated
many new features in the new typ"E" lamp and
lamphouse. The proportions of the lamphouse are
imposing, the extra large area facilitates an opera-
tor in being able to get inside the lamphouse to get
at any adjustment of the arc lamp. Two openings
in the front of lamphouse allows it to be easily and
readily cleaned.
Of paramount importance is the ventilation of the
lamphouse, hundreds of dollars are wasted annually
in condenser breakage solely on account of poor ven-
tilation in lamphouses.
The typ"E" lamphouse is so constructed to make
the ventilation scientifically correct.
Type "E" Lamphouse and Lamp showing Inside Dowser
186 MOTION PICTURE PROJECTION
6B. Equipment with Typ"E" Lamphouse complete with
Lamp Assembled
MOTION PICTURE PROJECTION 187
The condenser mount is mounted on a heavy grey
iron frame hinged to the lamphouse to open forward,
this allows the operator to bring the whole con-
densing set easily into full view for cleaning,' etc.
The condenser holders are made of an extra heavy
type of grey iron so constructed that the expansion
and contraction of the holders are fairly even and
Close-Up of Condenser Mount and Holder, and Adjustment
for Inside Dowser
that the heating and cooling off of the condensers
is accomplished gradually and evenly, this is a very
important point and helps in a great way to over-
come condenser breakage.
To assure the condenser proper alignment and
hold them securely in place, they are machined with
a "V" on two sides, fitting into a "V" groove on the
188 MOTION PICTURE PROJECTION
mount. Placed directly under the condenser mount
is an adjustment which controls the back condenser
(one nearest the arc) allowing the operator to space
his condensers to the exact local distance.
The lamphouse is equipped with an inside dowser
to protect the condensers from the heat of the arc
while the operator is "forming a crater," etc., the
dowser handle is placed on front of the lamphouse
directly above the condenser mount locking adjust-
ment. Radical changes have been made in the arc
lamp, it is built heavy enough to take care of any
amount of current up to 150 amperes ; the features
of the lamp are as follows :
1 Upper carbon holder designed to take from %
to 1%-inch carbon. Lower carbon holder 5/16-
inch to %-inch carbons, manufactured with the "V
Condenser Holder, Ring and Key
MOTION PICTURE PROJECTION
189
type, assuring a rigid hold on the carbons without
breaking them.
Upper and Lower Carbon Holder showing "V"-shaped inserts
and inter-locking corrugations for clamping wires
2 Both upper and lower carbon holders are
equipped with a clamp which is to take the place of
lugs for the wires. These clamps have been so manu-
factured of a series of interlocking corrugations on
both top and bottom of clamp so that when wires
have been clamped between them, they will have a
positive hold. To take care of any possible arcing,
the clamp and the carbon holder have been manufac-
tured of one piece.
3 Another feature of the lamp is the fact that
the lateral and backward and forward adjustments
are made on the lower part of the lamp so that on
Cross Section of Carbon Holder showing Position of Wire in
Inter-Locking Corrugations
190
MOTION PICTURE PROJECTION
adjusting the carbons, it will not change the posi-
tion of the crater of the upper carbon.
4 The fact that the raising and lowering of the
lamp is done by means of a worm wheel and gear,
gives the lamp additional rigidity.
5 Square steel bars held with a spring cover
have been used in the manufacture of the rack rods,
to take care of any expansion and giving same a
greater wearing surface.
Typ"E" Lamp. Note that the top carbon is stationary. The
lateral and back and forward adjustments are made on
lower carbon
MOTION PICTURE PROJECTION 191
Power's Cameragraph No. 6B
192 MOTION PICTURE PROJECTION
THE INTERMITTENT MOVEMENT
PRELIMINARY REMARKS
The moving picture is accomplished by flashing a
great number of stationary photographic views be-
fore the eye in such rapid succession that the eye is
deceived into the belief of having beheld actual mo-
tion.
The photographic views, which are usually taken
at the rate of sixteen per second, are printed in
direct succession upon a ribbon of transparent film
one and three-eighths inch in width and between one
and two thousand feet in length. Each view is con-
densed into a rectangular space approximately one
inch wide and three-fourths inch high.
When the film is run through the projector at nor-
mal speed, sixteen of these views are shown each
second. It would appear from this that each view
is shown for one-sixteenth of a second. Such is not
the case, however. Each view is held stationary
before the lens for only a part of this minute period
of time, and the remainder of the period is consumed
while the film is being moved down a distance of
three-fourths of an inch, so as to bring the succeed-
ing view in line with the lens.
During every such movement of the film, the main ,
blade (or wing) of a revolving shutter, passes in
front of the lens, thus preventing any trace of the
movements from reaching the screen. If this were
not done, the picture would be greatly marred by
streaks of light known as "travel ghost." An addi-
tional wing (and sometimes two) is inserted in the
MOTION PICTURE PROJECTION
193
shutter wheel for the purpose of doing what is tech-
nically known as "equalizing the light." We will
not discuss this matter of light equalization, as it
has no direct bearing upon the point that we wish
to bring out.
It is the necessary passage of these wings in front
of the lens that prevents an attainment equalling
theoretical perfection wherein each view would ap-
pear on the screen for its entire allotment of one-
sixteenth of a second without interruption of any
kind.
194
MOTION PICTURE PROJECTION
It would probably be possible to devise a way to
move the film so rapidly that the eye could not per-
ceive any trace of the movement, and thus the neces-
sity of using the revolving shutter would be eliminat-
ed, but we are prevented from doing this by the very
important fact that wear and tear on the film must
be taken into consideration. The movement of the
Fig. a
film must not be made so rapidly nor in such a
jerky manner as to cause the film to rip or pull
apart.
TECHNICAL DESCRIPTION OF THE
INTERMITTENT MOVEMENT
The term "intermittent movement" is used to des-
ignate that part of the mechanism of a moving pic-
ture projector, which performs the important func-
MOTION PICTURE PROJECTION
195
tion of stopping the film at regular intervals, so
that the photographic views may be successively
held in line with the lens.
This movement consists primarily of four elements,
namely: a diamond shaped cam, a locking ring, a
pin cross and a sprocket. Photographic views of
these parts will be found on page 193.
The cam and locking ring are formed together on
the face of a solid steel disc. The four pins of the
pin cross are formed from the end of a solid cylinder
of steel. The remainder of this cylinder is turned
down to the proper diameter to act as a spindle
upon which the sprocket is securely fastened. The
sprocket has two rows of teeth to mesh with the
holes that are perforated on each side of the film.
Figures a, 6, c, and d, show these elements in ac-
tion. A portion of the back of the cam-ring disc
Fig. b
196
MOTION PICTURE PROJECTION
has been cut away so as to expose the workings of
the movement during one revolution of the disc. The
curved arrows indicate the direction in which the
parts are revolving. The sprocket is in mesh with
a short strip of film. Portion e of this film, which
lies between the heavy black cross lines, represents
one of the photographic views to be projected upon
the screen.
Fig. c
In Figure o, the four pins of the pin cross are
shown in engagement with the locking ring. Pins 1
and 2 are at the outer circumference and pins 3 and
4 are at the inner circumference of the ring. Although
the ring is revolving, it cannot impart motion to the
pin cross, as the pins are securely locked by contact
with the inner and outer surfaces of the ring ; conse-
quently the pin cross, the sprocket and the film are
MOTION PICTURE PROJECTION
197
at rest. It is during this period of rest that the
photographic view is being projected on the screen.
In Figure 6, the* pins are disengaging from the
locking ring. The cam is just starting to engage
with pin 1. As the engagement takes place the pin
is pushed forward and upward, thus imparting a
rotary motion to the pin cross spindle. The sprocket,
being fastened to this spindle rotates with it, thus
pulling the film downward.
In Figure c, pin 1 has almost reached the apex
of the cam. Pin 2 is traveling into slot f, pin 3 is
describing an arc in the space between the ends of
the locking ring, and pin 4 is traveling out of slot g.
As piir-l slides over the apex of the cam, pin 4 en-
gages with the curved surface h at the end of the
locking ring, and the pin is thrown forward and
upward until it slides on to the outer surface of the
locking ring.
Fig. d
198 MOTION PICTURE PROJECTION
In Figure d, pin 4 has just reached the outer sur-
face of the ring. The four pins are immediately
locked as the locking ring travels into the space
between them. In contrast to the pin position in
Figure a, pins 1 and 4 are now at the outer circum-
ference and pins 2 and 3 are at the inner circum-
ference of the locking ring. It can readily be seen
that the pin cross spindle has made a quarter revolu-
tion, and that view e has been drawn downward a
corresponding distance.
Bear in mind that these pins can only move in the
path of a circle. As pins 2 and 4 travel through
their respective slots it would appear to the unini-
tiated mind as though the pins must travel in a
straight line. This is not the case, however. The
fact that the cam-ring disc is revolving, constantly
changes the position of these slots so that their
MOTION PICTURE PROJECTION 199
straight lines intersect the circular path of the pins
at successively different points.
One great advantage that this particular move-
ment has to offer, may be demonstrated by making
the following simple experiment:
Tie a one foot length of ordinary cotton thread to
a piece of metal weighing slightly over one pound.
Take the untied end of the thread between the fingers
and by an upward pull, endeavor to lift the piece of
metal a distance of one foot in the shortest possible
time. A sudden jerk will snap the thread. A slow
upward pull will allow the thread to stand the strain
of the weight, but considerable time is consumed in
lifting the metal. If the slow pull is exerted until
the metal has started to move, the pull may then be
steadily increased, and consequently the metal can
be lifted much more quickly.
This analogy may be applied to the star and
Intermittent Movement with Oil-Tight Casing
200 MOTION PICTURE PROJECTION
cam intermittent movement, which has been care-
fully designed, to move the film downward, by start-
ing the motion with a scarcely perceptible pull that
steadily increases to a maximum as pin 1 (Figure c)
slides over the apex of the cam, after which it de-
creases in the same steady manner until the pins are
locked by the ring, and the film is again at rest. Not
A magnified view of the pin cross of the Power's Machine,
with and without roller bearings in place
a moment of time is lost, and yet the film is moved
so easily that the wear and tear is reduced to a
minimum.
The elements of the intermittent movement are
made from carefully selected tungsten-chromium
steel, which is very tough and durable. The most
delicate instruments are used in measuring the dimen-
MOTION PICTURE PROJECTION 201
sions of the elements, one ten-thousandth of an inch
plus or minus being the limit of permissible variation.
The cam and pin cross are enclosed in an oil-tight
casing. An oil cup is fastened to this casing, and by
keeping the parts plentifully supplied with a high
grade machine oil, a practically noiseless operation
of the movement without perceptible wear on the
parts, is insured.
Detailed views of the new movement, showing the cam with the
disc which holds the roller bearings in place,
and the pin cross with bearings removed
202 MOTION PICTURE PROJECTION
Power's Cameragraph No. 6A
Showing film threaded through machine
MOTION PICTURE PROJECTION
203
WORKING OPERATION OF POWER'S
LOOP-SETTER
The illustration shows a strip of film forming the
lower loop around roller (A). When the loop is lost
(drawn taut), the roller is necessarily elevated, thus
causing a slight rotary motion in cylinder (B). A
diagonal slot in this cylinder, in contact with a pin
fastened to arm (E), causes the arm to move out-
ward; but as arm (C) operates as a lever, with its
fulcrum at point (D), the other end of the arm at
Automatic Loop-Setter
(E) moves inward, thus disengaging pin (F) from
the driving pulley (G). This breaks the connection
whereby motion is transmitted to take-up sprocket
(H), and the sprocket stops revolving. The loop re-
204
MOTION PICTURE PROJECTION
forms instantly, and roller (A) is forced back into
its original position by coil spring (I). Pin (F)
immediately re-engages with driving pulley (G), and
the take-up sprocket (H) starts to revolve again as
a natural consequence. The whole train of opera-
tion is automatic its results instantaneous.
MOTION PICTURE PROJECTION 205
6B WITH TYPE "E" LAMPHOUSE
206 MOTION PICTURE PROJECTION
POWERS TAKE-UP
MOTION PICTURE PROJECTION 207
POWER'S 6B TAKE-UP
The 6B Take-up is simplicity itself. It consists
primarily of two friction discs, which are held in
contact by means of a spring. One of these discs is
faced with fibre, which assures an excellent frictional
contact. The driving disc (a) is left free to revolve
around Take-up spindle (b), as an axis. The driven
disc (c) is fastened to spindle (b). By frictional
contact, motion is transmitted from disc (a) to disc
(c) and thus spindle (b) is caused to revolve
also. The take-up reel fastens to spindle (b) at (d).
The reel is held firmly on the spindle by means of
catch (e). When the catch is in a horizontal posi-
tion, it is in exact line with spindle (b), thus mak-
ing it very easy to put the reel on, or take it off the
spindle. Spindle (b) runs in ball bearings (f), which
eliminate all unnecessary friction in operation.
As the film winds on the reel, the steadily increas-
ing load gradually retards the speed at which disc
(c) revolves, and this automatically regulates the
revolutions of the Take-up reel, so that at every
moment the proper tension on the film is assured.
The friction between discs (a) and (c) may be
adjusted by increasing or decreasing the tension on
spring (g). This may be accomplished by simply
giving a few turns in either direction, to collar (h),
which is threaded on the end of spindle (b). When
the desired tension has been secured, the collar may
be locked in place by means of set screw (i).
208 MOTION PICTURE PROJECTION
AUTOMATIC SHUTTER
The shutter covering the aperture in gate of ma-
chine and controlled by the centrifugal movement. It
is so arranged that the shutter will be held up by
centrifugal force as long as the machine is in motion,
but should the machine stop for any reason then the
shutter falls and cuts off the light from film. It is
625
741
The Centrifugal Movement with Cover Removed
a fire prevention device. Should the automatic
shutter refuse to work and same cannot be remedied
by oiling, it will then be necessary to take the cover
off the centrifugal movement Figure 624, then exam-
ine springs and shoes Figure 741, and see if the shoe
track Y is not scratched.
MOTION PICTURE PROJECTION 209
MOTOR TROUBLES & REMEDIES
Sparking may be due to overload, wrong position
of brushes, broken coil, weak field, and to any of the
causes named for dynamos.
Sparking
Symptom. Intermittent Sparking. On a varying
load, in which the work comes on, at the beginning
or end of each cycle, and then falls off during the
remainder of the cycle, a motor often sparks just as
the peak load comes on.
The cause is the heavy current taken at the in-
stant of maximum load, which distorts and weakens
the effective field and shifts the neutral point. This
weakening of the field results in a still larger current
in the armature, aggravating the evil.
Remedy. Add a compounding coil on the motor
to assist the shunt, or exchange the motor for a com-
pound-wound one, or one with interpoles.
Failure to Start
(1) Symptoms. Motor does not start. Little or
no current passes on closing the D.P. switch and
pushing starting handle over.
Probable Causes. Brushes not down. Switch not
making contact in the jaws. Starting switch not
touching the contacts. Fuse broken. Controller
fingers not touching contact plates. Break in series
coil (if a series motor). Terminal loose. No cur-
rent on mains.
210 MOTION PICTURE PROJECTION
If the no-volt release coil excites, or if a long arc
is observed on breaking circuit, it indicates that the
shunt field gets its current and the probable cause
of the failure to start is that the shunt is connected
in series with the armature owing to two of the leads
from the starter being reserved.
Remedy. Trace out the connections or use test-
ing set.
Failure to start
(2) Symptom. Motor does not start, but takes
excessive current. Fuse or overload cut-out acts.
Cause. It is assumed the motor is not overloaded ;
this can be tested by taking load off and trying to
start motor light. If a shunt motor there may be
a short circuit in connecting cables or in field coil;
or in armature ; or a break in field coil.
Remedy for broken field. If field excites when
brushes are up, but not when they are down, the
symptoms point to a short circuit in or across arma-
ture, or brushes.
Examine brushes for short circuit to frame, for
copper dust, oil, or broken down insulation.
Then disconnect armature and excite field. Move
armature round quickly by hand. A drag will be felt
as the short circuited coils pass the poles. If the
armature can be driven at a fair speed by belt, with
the field excited, the short-circuited coils will warm
up and can probably be located in this way.
If the above symptoms occur with a series-wound
motor, the cause may be a short in the field or arm-
ature, but not a break.
MOTION PICTURE PROJECTION 211
A fairly common cause is incorrect connecting up.
Another cause, particularly with machines that
have been dismantled, is incorrect polarity of the
field coils. Thus if the coils are connected up so that
they are all of the same polarity, the effect is the
same as with a broken field wire as the field is com-
pletely neutralized. If only one of the field coils is
reversed in a four-pole motor, the motor would prob-
ably not start and would in any case take an exces-
sive current.
Remedy. Test the coils for polarity.
Incorrect Speed
A certain amount of speed adjustment may be ob-
tained by altering the position of the brushes. Mov-
ing the brushes backwards from the neutral point has
the effect of increasing the speed, whilst moving them
forward reduces the speed.
Excessive Speed
Symptom. Motor starts, then speed gradually in-
creases till motor runs at very excessive speed. This
only occurs when a motor starts light or on a very
light load such as a loose pulley.
Cause. If shunt or compound motor. Shunt coil
connected in series with armature instead of in
parallel.
On first switching on, the magnets excite, as the
armature is stationary and allows the full shunt
current to pass the coils. As the armature speeds
up it puts a back E.M.F. in the circuit, gradually
reducing the current passing and thus weakening the
212 MOTION PICTURE PROJECTION
field. The faster the armature goes the weaker the
field becomes. A short circuit in the shunt might
produce same result if motor starts absolutely light.
Remedy. Connect up the shunt.
Fuse Blows
Symptom. Motor starts and runs up to its proper
speed, but fuse or overload acts on putting load on.
Cause. This is a sign of overload. Probably belts
too tight, bearings tight or dry.
If the fuse blows whilst starting up there may be
a ground on the motor. This should be tested. If
the starter is provided with shunt sector the fuse
may blow whilst starting up, owing to a bad contact
to this sector, due either to dirt or to a hollow place
in the metal.
In the case of a compound-wound motor a cross
connection or leakage between the series and shunt
windings will cause the fuse to blow if the cross is
in a position that the shunt is practically short cir-
cuited by the series.
Starter Overheats
Symptom. Motor starting against load takes ex-
cessive current. Last few coils of resistance overheat
(probably smoke or get red hot). Fuse or overload
acts, or motor sparks.
Cause. Overload ; or starter too small.
When a motor starts against a load having con-
siderable inertia, such as heavy line shaft with several
large pulleys and tight belts, or against a heavily
fly-wheeled machine, time must be given for it to get
MOTION PICTURE PROJECTION 213
up speed. If the starter is moved over the contacts
more quickly than the motor can accelerate, an ex-
cessive current will pass, causing the motor to spark.
The starter must be put on more slowly and this will
cause it to heat up unless it has been liberally rated.
Remedy. Exchange starter for one having more
margin, that is one which permits of starting up
slower. This does not mean a starter for a larger
H.P.
Starts Suddenly
Symptom. Motor does not start nor take current
till most of resistance is cut out, then takes rush of
current and starts suddenly.
Cause. A break in the starting resistance.
Temporary Remedy. Connect the contacts where
break occurs, until resistance can be repaired.
Wrong Direction
Symptom. Motor runs in wrong direction.
Remedy. Reverse armature or field connections,
whichever is the easier, but not both.
In a compound-wound machine both the shunt and
series coil must be reversed if the field be reversed;
but if the machine be provided with interpoles these
must be treated as part of the armature and must
therefore not be reversed when the field is reversed.
Motor Reverses
Symptom. Motor starts up and runs correctly
on light load. On an overload, or reduced voltage,
motor reverses and runs backwards.
Cause. This applies to a compound-wound motor,
with the series or compound coil connected up in
opposition to the shunt coil.
214 MOTION PICTURE PROJECTION
Remedy. Reverse the series coil.
Flashing
Symptom. Severe sparking or flashing apparently
all round the commutator ; over-heating of the arma-
ture and burning of the insulation between a couple
of the segments.
Cause. The cause of the above is a broken wire
in the armature winding.
Remedy. If the broken end cannot be located and
repaired easily, the armature must be stripped until
the break is found and the section re-wound. A
temporary repair can sometimes be made sufficiently
to enable the motor to continue working, by joining
across the two segments on each side of the burnt
mica with a short piece of copper wire, the wire
being laid on the ears of the commutator and sweated
in with a soldering iron. This practically converts
two segments into one, and the motor will run in this
way quite satisfactorily. If the commutator lugs
are not readily accessible, a copper pin may be driven
hard down between the two segments in a part not
under the brushes.
Flashing Over
Symptom. On an overload and sometimes on a
normal load a motor will flash from the brushes to
a part of the commutator or to the rocker, and blow
the fuses. This is more liable to happen with a
weak field.
Cause and Remedy. The cause is that the motor
has too much forward lead, and the brushes should
be moved back a little.
MOTION PICTURE PROJECTION 215
ROBIN SIGNAL TELEGRAPH SYSTEM
The Robin Signal Telegraph system is an audible
and visual signal system which provides a positive
means of transmitting co-ordinated signals between
the operating room, stage, and orchestra pit with
certainty and dispatch.
The system consists of a master station which
is placed on the stage director's stand or on the
orchestra leader's desk, and is connected with the
orchestra pit and meters in the booth.
The signal dispatch station consists of a panel
board and a radial switch with several contacts. In
operation the switch can be set at any point desired
as far in advance as desired and when the button
is pushed, will call the operator's attention to the
signal.
Robin Signal Telegraph With Eight Synchronized Meters as
Installed in New York Capitol
216 MOTION PICTURE PROJECTION
At the master station is provided an instrument
similar to those installed in the booth, and which
serves the purpose of a master meter and conveys
to the director or leader sending the signal, means
of ascertaining the correct working of the system
and also as a telltale of whether the instruments in
the booth are registering the correct signals. If
the master meter does not function, none of the
others will operate.
The meters in the booth are generally placed one
under each look-out hole, that the operator, no mat-
Robin Signal Telegraph Despatch Station
MOTION PICTURE PROJECTION 217
ter where located, receives the same signal. Each
meter has a plate provided with a scale on which
is engraved, "ready, go, stop, slower, faster, see
programe, light, focus, and frame."
This instrument supersedes the use of the tele-
phone and the ordinary and troublesome return call
buzzer system.
In actual operation instead of the leader or stage
director telephoning to the operator and calling him
away from his projection machines he throws the
switch over on the signal and presses the button and
the operator, without leaving his position receives
both an audible and visual signal.
At the rear of the control board on the master
station is mounted a capirating rheostat with re-
sistance to correspond with the various points on the
scale. There is also provided an adjusting rheostat
to compensate any drop in voltage or differences be-
tween the points of the scale
Wire required from the booth to the orchester pit
is five No. 16 B & S gauge wires, two for the signal
and three for the return call.
The source of energy is dry batteries and one set
of cells, this being sufficient for an entire year.
218
MOTION PICTURE PROJECTION
CARBONS
There are two classes of carbons generally used in
arc lamps, solid and cored; they are composed of
coke, tar, or the graphite deposited in the inside of
retorts used for manufacturing illuminating gas.
With solid carbons the crater travels around the
ends of the carbons, the current always tending to
take the path of least resistance ; with cored carbons,
which are solid except for an inner core of softer
carbon, the travel of the crater is reduced and the
distribution of light more steady. The effect of the
core is to confine the current to the center of the
rod, and consequently the arc, due to the core hav-
ing a higher conductivity than the surrounding ma-
terial. With cored carbons the voltage across the
arc is reduced.
-JSL
\J
t
( /
// /
/ / -
f\
Right and wrong way to set D. C. arc. I. Lower carbon
not far enough forward. II. Correct setting.
III. Lower carbon too far advanced
MOTION PICTURE PROJECTION 219
In an alternating current arc the crater alter-
nates from one carbon to the other with each reversal
of current, so that both carbons are consumed equal-
ly when the rods are horizontal. When vertical, the
upper carbon will be consumed about 8 per cent,
faster, owing to the action of the ascending currents
of heated air.
The Projection Arc
Since the experience of some operators has been
limited to projection with the alternating-current
arc, the following suggestions are offered on projec-
tion with the direct-current arc :
The direct-current arc should be approxi-
mately 5/16 to % inch long or about twice the
length of the alternating-current arc. Too short
an. arc will not give a satisfactory light, the trouble
being not in the machine but in the carbon setting.
Use only the best projection carbons. Pro-
jection 'carbons vary greatly in quality and good
results cannot be obtained from poor carbons. In-
ferior carbons are particularly liable to give trouble
on arc currents of 50 amperes and above. Good
carbons will be uniform in diameter, straight, free
from cracks running around the circumference, and
uniform in density throughout. The core will be
true to the center of the carbon and will not drop
out while burning. A hard spot in the carbons will
cause the arc to jump and sputter, while a soft spot
will cause it to flame or needle and burn away very
rapidly. The main point in setting the carbons is
to get a crater to form good size and facing the
center of the condenser lens as nearly as possible.
220
MOTION PICTURE PROJECTION
Take care to have the carbons in perfect
alignment sidewise and a long enough arc that the
lower carbon does not "mushroom." Pull the upper
carbon back slightly which will face the crater
forward toward the condenser. If the upper carbon
is not back far enough the crater will point down-
ward and not toward the condenser. If too far
back, a long "skirt" will form on the back edge of
the upper carbon which will give an unsteady light
and may break off in feeding, giving a very poor
light until a new crater can be formed.
Do not try to decide upon the merits of carbons
by burning just one carbon of a kind in just one
"Columbia."
UPPER CARBON
Correct Setting
FRONT
MOTION PICTURE PROJECTION 221
way; try out a carbon setting at least one whole
day to see if results cannot be improved.
There has come into use recently a small diameter
metal coated hard core negative carbon which has
been found in many cases to improve the operation
of the arc by holding it quiet and steady.
CARBON COMBINATIONS FOR NATIONAL
CARBONS
DIRECT CURRENT
Current Size Carbons
For 25 to 60 Amps. ( 5/8 x 12 inch Cored Upper
D. C. use ( 5/16 x 6 inch Metal Coated Solid Lower
For 50 to 65 Amps, f 3/4 x 12 inch Cored Upper
D. C. use { 11/32x6 inch Metal Coated Solid Lower
For 65 to 70 Amps. C 7/8 x 1C inch Cored Upper
D. C. use I 11/32x6 inch Metal Coated Solid Lower
For 70 to 85 Amps. C 7/8 x 12 inch Cored Upper
D. C. use | 3/8 x 6 inch Metal Coated Solid Lower
For 85 to 100 Amps, f 1 x 12 inch Cored Upper
D. C. use (7/16x6 inch Metal Coated Cored Lower
ALTERNATING CURRENT
Amperes Carbon Diameter
40 or less than 60 5/8 inch Combination
60 or less than 75 3/4 inch Combination
75 or less than 100 7/8 inch Combination
Projector Carbon Manufacturing Process
In the manufacture of high-grade projector car-
bons it is necessary to use an especially prepared
carbon flour. The flour is carefully mixed with the
necessary binding material and forced by hydraulic
presses under high pressure into the desired shape.
220
MOTION PICTURE PROJECTION
Take care to have the carbons in perfect
alignment sidewise and a long enough arc that the
lower carbon does not "mushroom." Pull the upper
carbon back slightly which will face the crater
forward toward the condenser. If the upper carbon
is not back far enough the crater will point down-
ward and not toward the condenser. If too far
back, a long "skirt" will form on the back edge of
the upper carbon which will give an unsteady light
and may break off in feeding, giving a very poor
light until a new crater can be formed.
Do not try to decide upon the merits of carbons
by burning just one carbon of a kind in just one
> J
ColuYnbx a."
UPPtP CARBON
Correct Setting
MOTION PICTURE PROJECTION 221
way; try out a carbon setting at least one whole
day to see if results cannot be improved.
There has come into use recently a small diameter
metal coated hard core negative carbon which has
been found in many cases to improve the operation
of the arc by holding it quiet and steady.
CARBON COMBINATIONS FOR NATIONAL
CARBONS
DIRECT CURRENT
Current Size Carbons
For 25 to 60 Amps. J 5/8 x 12 inch Cored Upper
D. C. use [5/16x6 inch Metal Coated Solid Lower
For 50 to 65 Amps. C 3/4 x 12 inch Cored Upper
D. C. use ( 11/32 x 6 inch Metal Coated Solid Lower
For 65 to 70 Amps, f 7/8 x 10 inch Cored Upper
D. C. use I 11/32 x 6 inch Metal Coated Solid Lower
For 70 to 85 Amps, f 7/8 x 12 inch Cored Upper
D. C. use (3/8x6 inch Metal Coated Solid Lower
For 85 to 100 Amps, ( 1 x 12 inch Cored Upper
D. C. use I 7/16 x 6 inch Metal Coated Cored Lower
ALTERNATING CURRENT
Amperes Carbon Diameter
40 or less than 60 5/8 inch Combination
60 or less than 75 3/4 inch Combination
75 or less than 100 7/8 inch Combination
Projector Carbon Manufacturing Process
In the manufacture of high-grade projector car-
bons it is necessary to use an especially prepared
carbon flour. The flour is carefully mixed with the
necessary binding material and forced by hydraulic
presses under high pressure into the desired shape.
222 MOTION PICTURE PROJECTION
If a cored carbon is wanted, a steel needle is suspend-
ed in the center of the die. The forced carbons are
then placed on racks to cool and when sufficiently
cool they are cut in the proper length for baking.
To insure absolute straightness, correct size and per-
fect stock before baking, the cooled carbons are
thoroughly inspected before being turned over to the
baking department.
In the furnaces, the carbons are subjected to the
temperature necessary to produce a uniform carbon
of certain definite prescribed qualities. After the
bake is completed, the furnace is sampled and the
carbons examined by the testing department before
being sent along for finishing. These tests are even
more severe than those to which a projector carbon
is subjected by the user.
Upon receiving the testing department's O.K., the
carbons are sorted for straightness and examined for
imperfections, and if they are hollow shells, made
ready for coring. Every precaution is taken in the
coring department, where the hollow shells are filled
to see that the core material fills the entire length
of the carbon. The composition of the coring ma-
terial is of considerable importance as it determines
largely the burning quality and color of the arc.
After coring, the carbons are dried, finished, pointed,
inspected and placed in the shipping stock.
The Carbon Arc
In the direct current arc, the crater of the positive
carbon forms the principal light source. The posi-
tive crater is of relatively large area, while the nega-
tive spot is small and is not usually considered as a
MOTION PICTURE PROJECTION 223
light source. While 95% of the light emitted by the
arc comes from the positive crater, the character-
istics of the negative carbon are of vital importance
in securing steadiness of operation. In operation,
1
Fig. 1 p ig< 2
the positive crater is set so as to face the axis of
the optical system. In setting the carbons in this
position, care must be taken to reduce to a minimum
the shading of the crater by the negative carbon.
In this respect, the direct current arc is superior
to the alternating current arc. A direct current arc
is longer and therefore gives less shading of the
crater. The greatest advantage of the direct cur-
rent arc is the fact that the current travels only
in one direction and therefore the positive crater re-
ceives electrical energy continously and consequently
maintains a higher temperature.
As was stated above the characteristics of the
lower carbon on direct current are of greatest im-
portance in securing steadiness of operation. The
size of the upper carbon is determined by the power
224 MOTION PICTURE PROJECTION
imputed to the arc. If the positive is too small the
current will overlap the end of the carbon and the
arc will be noisy and unsteady. If too large, the
crater covers the end of the carbon and the arc
again will be unsteady, because the average temper-
ature at the tip is lower. With the negative car-
bon, the carrying capacity is the important factor
since the size of the negative carbon required by the
negative spot is small. A small carbon keeps the arc
steady and also eliminates the shadow due to the
shading of the crater by the negative carbon itself.
This problem has been solved by plating the solid
negative over its entire length with a series of metal-
lic coats forming a shell of metal of low electrical
resistance around the carbon. This metallic coating
volatizes in the heat of the arc and thus prevents
the spattering of the rear condenser lens with the
heavy metal beads formed with the old style metal
coat. The coating carries the major part of the
current and makes possible the use of a small nega-
tive with the high currents required by long throws
and dense films.
The direct current arc is inherently stable and the
range of arc voltage can be made whatever the pro-
jectionists desire, but there is one fact to be borne
in mind that, for each given current value there is
a definite arc voltage at which the arc operates at
maximum efficiency. With a constant current value,
gradually shortening the arc length, will finally pro-
duce an unstable arc; just previous to that point is
the limiting voltage for the current chosen. Or,
otherwise, a given current requires a certain arc
length of voltage. To increase the current and not
change the arc length, is equivalent to shortening the
MOTION PICTURE PROJECTION
5225
arc in the first case and the arc becomes noisy. For
this reason increasing voltages are required for in-
creasing currents.
When using small diameter solid metal coated
negatives on direct current we start at 52 volts for
30 amperes and increasing by 2 volts for each in-
crease of 10 amperes, reaching 62 for the arc voltage
at 100 amperes, a saving of 0.7 kw. or 10 percent,
in arc wattage, than in case where the old style large
diameter cored negatives are used, starting at 55 arc
Bevkd tpd
COttDfcftdERS
volts for 30 amperes direct current, and increasing
voltage and current in same proportion as recom-
mended in former case.
In the past when using cored negative carbons the
basis for choice of the negative was a ratio of 1 for
the negative diameter, to 1.65 for the positive dia-
meter, or a cross-sectional ratio of 1.2.
226 MOTION PICTURE PROJECTION
Under the table of Carbon Combinations for direct
current projection, the new developed solid small
diameter metal coated negative calls for a cross-sec-
tional ratio of 1.4, the negative having y\ area of
the positive.
What determines the size of a carbon for given
service is the ability to stand up under it but the
limiting factor differs in A. C. and in D. C.
On direct current the limiting factor is the crater.
Since the temperature of a carbon arc is constant
just as is the temperature of boiling water be there
a teaspoonful or a barrel full so, by putting into
the carbon more current, we merely increase the num-
ber of the hot, light-giving areas until finally the tip
of the carbon or crater can no longer accommodate
an increase and then no further increase of light is
possible for that carbon. The body of the carbon is
as yet unaffected by the current but the crater can
no longer take care of further increases. This is
the limiting factor and so we take the next larger
sizes.
On alternating current the crater is but half the
size of the crater formation on direct current, owing
to the fact that the energy' is divided equally between
the upper and lower carbon; therefore, we can go
still higher in current density on A. C. without reach-
ing a crater limit but we now find that the carbon
body cannot carry an unlimited amount of current
without glowing and oxidizing away sharply, so we
are limited on A. C. to the physical characteristics
of the carbon. Using the old style alternating cur-
rent carbon, a short air gap gives a hissing and sput-
tering arc which is very unstable. By using cored
carbons, the cores of which are impregnated with
MOTION PICTURE PROJECTION
227
carefully prepared chemicals, an absolutely silent
and steady alternating current arc can be obtained.
By using the proper chemicals a light source of high
intensity is obtained which is far above that of the
old cored carbons.
This change in the construction of carbons for use
with alternating current projection is one that has
come to the front in the last year and has met with
A Mushroom Arc
marvelous success. It has brought the alternating
current arc in close competition with the direct cur-
rent arc and it has allowed many houses who had
seriously considered adopting other sources of illu-
mination to continue with the alternating current
arc without necessitating a single change in or about
the lamp house or in the wiring. The mere substi-
tution of these new carbons for the old style alter-
nating current carbons makes the alternating current
arc a very desirable and economical light source for
projection.
228 MOTION PICTURE PROJECTION
In addition to fulfilling the general requirements,
the carbon arc has other characteristics which make
it adaptable for motion-picture work. These char-
acteristics are: Color of light; Reliability; Flexi-
bility ; Steadiness.
Color of Light: Until recently, the color of the
light used for the projection of the high-class film
was a source of much annoyance. It is obvious that
where the picture is taken in the open and in bright
daylight, the effect upon the screen would be inferior
unless the projection light source approached that
of daylight in color value. The light of the direct
current arc is the nearest approach in color value to
daylight of any of the known illuminants that could
be used for motion-picture projection. The light is
a pure white of high intensity. The light of the al-
ternating current arc using the modern high-grade
projector carbon approaches that of the direct cur-
rent arc both in color value and intensity. A pure
white light is beyond doubt the proper kind of light
to use for projection since it brings out the high
lights and shadows and will project upon the screen
a picture that will please the most critical audience.
Reliability: The arc in the hands of an efficient
projectionist, is a very reliable light source. It is
not easily affected by fluctuations in line voltage and
therefore will give an even screen illumination where
other illuminants will fail. Carbons have a definite
length of life and therefore the projectionist can
guard against the failure of light in the middle of
a reel of film.
Flexibility : The carbon arc gives a steady, flexible
light, variable at the will of the operator according
to the density of the film. No two films are alike and
MOTION PICTURE PROJECTION
229
no two parts of the same film are of the same density
and consequently to give a true artistic presentation
of any picture you must have a flexible light source.
Steadiness : Both the direct and alternating cur-
rent arcs are giving absolutely steady illumination.
The traveling of the arc and negative shadows have
been eliminated in arc projection.
In conclusion, emphasis should be placed upon the
use of proper carbon combinations. The carbon
manufacturer specifies a definite diameter of carbon
for a definite current requirement and any deviation
from this will result in poor projection. If the
projectionist is without positive knowledge of the
amount of power he is using he can obtain this by
means of a voltmeter and ammeter. Standard in-
struments for this purpose can generally be obtained
from the local power plants.
Showing effect of arc being connected upside down
23d MOTION PICTURE PROJECTION
THE SPEER CARBON
Speer Projector Carbons have a texture designed
to withstand high current densities and insure long
life, but soft enough to give a pleasing, steady, white
light of great intensity. In order to meet the de-
mand for service of the highest class, three types are
offered the trade. The Directo Carbon is made es-
pecially for D. C. positives, but may be used as D. C.
negatives. It is of the soft cored type and is dis-
tinguished by .the perfect flush crater developed.
The Hold-Ark Carbon, of the hard cored type, is
made for D. C. negative work only, is double electro-
plated and is extensively used by projectionists who
desire a noiseless, steady, white light. The Alterno
combination sets are the highest development of car-
bons for A. C. service and produce a noiseless white
arc. They are furnished in packages containing 25
12" carbons and 50 6" carbons. The 12" carbon
marked with a yellow line must be used only as the
upper and the 6" carbon marked with a white line
must be used only as a lower.
The best screen results are obtained with the fol-
lowing sizes:
For D. C. Service:
25 to 50 amperes 5/8x12" Directo and 5/16" Hold-Ark
50 to 70 " 3/4 x 12" " " 11/32"
70 to 85 " 7/8 x 12" " " 3/8"
85 to 100 " 1 x 12" " " 7/16"
For A. C. Service:
85 to 55 amperes 5/8" Alterno Combination
55 to 70 " 3/4"
70 to 85 " 7/8"
MOTION PICTURE PROJECTION 231
Speer
Projector Carbons
DIREGTO Positives for Direct Current
HOLD-ARK Negatives for Direct
Current
ALT ERNO White Light -Noiseless Sets
for Alternating Current
Cored, Solid and Metal-Coated Carbons,
Searchlight Carbons,White Flame Carbons
for Studio Work, Photo Engraving and
Spotlight Carbons.
Manufactured By
SPEER CARBON COMPANY
ST. MARYS, PA., U.S.A.
232 MOTION PICTURE PROJECTION
THE ELECTRIC ARC
When a current, under a pressure, is passed
through two carbon rods, with their ends first
in contact and afterward gradually separated a
short distance, a brilliant arc of flame called the
electric arc, is established between them. This arc
is composed of carbon vapor, that is, the high tem-
perature caused by the passage of the current
through the resistance of the contact surfaces causes
the carbon to practically boil and the vapor thus
arising, being a much better conductor than the air,
conducts the current across the gap from one carbon
tip to the other. This volatilization occurs chiefly
at the end of the positive carbon terminal where the
current enters the arc, and this point is also the seat
of the highest temperature and maximum light-
emitting power. As the arc is maintained across the
gap, disintegration of the carbon takes place, the
carbons waste away, and a cup-shaped depression,
termed the crater, is formed in the positive carbon,
while the tip of the negative carbon has a conical
form. The negative carbon being at a lower tem-
perature than the positive, the vapor of the boiling
carbon condenses upon its surface as pure graphite.
Both carbons waste away, but the consumption of
the positive carbon is about twice as rapid as that of
the negative, since it is this carbon from which most
of the vapor comes and part of which is re-deposited
as graphite on the negative cone-tipped carbon.
The light emitted by any heated body increases
with its temperature. The temperature of the car-
bon in the crater, when in a state of ebullition, is
about 3500 C., this being the hottest portion of
MOTION PICTURE PROJECTION 233
the arc, and consequently the point from which the
most light is emitted. About 12 per cent of the
energy supplied to an electric arc appears as light,
the balance being represented by the heat evolved.
About 85 per cent of the light emitted from an arc
lamp is reflected from the crater, the maximum il-
lumination being in a zone surrounding the lamp at
an angle of about 40 to the horizontal.
When the arc is "struck" by bringing the carbon
electrodes together, and the.n, separating them for a
short distance, the arc possesses peculiar character-
istics depending upon the length of the gap between
the ends of the carbons. When this distance is too
small the arc emits a peculiar hissing noise, and is
called a hissing arc. It is caused by a too rapid
volatilization of the carbon, due to the excessive cur-
rent that would flow through the lamp with a short
gap between the carbons. Spluttering sounds pro-
duced by the arc are due to impurities in the carbon,
or loose-grained carbons. By adjusting the distance
between the carbons, a point wih 1 be found where the
arc burns quietly and steady, and is then termed a
normal or silent arc ; if this 'distance be exceeded the
arc flames. Impure carbons, or carbons not prop-
erly baked, will produce a flaming arc, which is ac-
companied by a loss of light and rapid increase in
carbon consumption.
234 MOTION PICTURE PROJECTION
FILM
Motion picture film is a strip of flexible, supple,
transparent celluloid l^g" wide. One side of the film
is given an emulsion coating much the same as on
an ordinary photographic film pack. The margin
of the film is perforated, there being 64 perforations
to the foot of film or four on either side of each pic-
ture (16 pictures to one foot of film) these perfora-
tions are for the purpose of feeding the film through
the camera or projector. The film comes to the pro-
jectionist on metal reels, each reel containing ap-
proximatly 1,000 feet of film, generally five or six
reels making one feature picture. The projectionist
should always examine his film before running it
through the projector; this he does by running the
film from one reel on to another, by using a re-
winding machine and letting the film pass between
the first finger and thumb of the left hand; care
should be taken to see that all patches are se-
cure, that the film is free from "frame-ups" and
that the perforations are in such a condition
that the film will pass readily through the pro-
jector without jumping off the sprockets. The
reels should then be placed in a fireproof film
cabinet in chronological order, care being taken to
see that the film is wound on reels emulsion side out
and that the beginning of the film subject comes off
first, in other words that the film does not go through
the projector tail-end first. Remember that the film
passes through the projector upside down and emul-
sion side to source of light. As soon as the film has
passed through the projector it should be rewound
MOTION PICTURE PROJECTION 235
and placed back into the safety cabinet ready for
the next show. The majority of film exchanges re-
quest that the film be returned to them unrewound
just as it is taken off the projector after it has been
run, it being the rule in exchanges that the film be
examined starting at the end and working back to
the beginning of. the subject; this is to eliminate the
risk of their sending the picture on to the next
theatre, tail-end first. Care should be taken to see
that all pieces of film are kept off the floor of the
operating and rewinding room ; a special can fitted
with a self-closing door or lid should be a part of
the necessary equipment of the operating room.
Film should at all times be handled with great care,
as owing to the ingredients from which it is made,
mtro-cellulose and camphor, it is highly inflammable.
Never under any circumstances expose film near a
naked light; do not smoke while handling film or in
a room where film is stored ; film should not be stored
in a warm dry atmosphere unless it is kept in a
humidor. Do not attempt to run a show if using
inflammable film without having the projector en-
closed in an approved fireproof booth; perhaps an
editorial we prepared for the Educational Film
Magazine on this subject will be appropiate here.
In New York State and, in fact, every state of
the Union certain very stringent rules and regula-
tions have been drawn up and must be complied with
before it is possible to obtain a permit for the pur-
pose of showing motion pictures. We advise all
those in any way interested in the showing of motion
pictures to get a copy of the law and read it care-
fully over.
236 MOTION PICTURE PROJECTION
The code distinctly states that no motion-picture
machine shall be used unless same has been approved
by the Board of Fire Underwriters. This board
demands that all motion-picture machine manufac-
turers shall make the machines as fireproof as pos-
sible; the machine must be so constructed that only
a short length of film can be exposed while the
machine is in operation. The machine must be equip-
ped with an automatic fire shutter, so arranged that
the shutter will immediately drop in case of trouble
and thus cut off the heat of the arc lamp from the
film.
The law then goes on to state that even this ma-
chine equipped as it is with all these fire prevention
devices shall not be used unless the said machine is
installed in a fireproof booth. They are as par-
ticular regarding the booth as they are with the ma-
chine; the booth must be constructed of asbestos,
concrete, brick, or some other approved fireproof
material. Certain minimum dimensions are given as
the size of the booth and it must have a door that
is automatically self-closing. The projector and
observation ports in the booth must be equipped with
metal or asbestos shutters, so arranged that they
will automatically close in case of fire in the booth.
There must be a flue or vent running from the booth
to the open air to carry off the smoke in case of fire.
The booth must also contain fire bucket, pails of
sand, and fire extinguishers.
Now that we have a fireproof projecting machine
installed in a fireproof booth, the authorities go one
better and state that with all these precautions there
is still a great danger of fire unless a duly qualified
MOTION PICTURE PROJECTION 23T
licensed man is placed in charge of the handling of
film and the operating of the projection machine.
They demand that theater managers shall take all
these necessary precautions against fire on account
of the highly inflammable nature of the film. Both
the theater manager and the professional operator
lay themselves open to severe penalties should they
not live up to the letter of the law. These rules are
not laid down to throw obstacles in the way of those
desirous of showing motion pictures; they were
drawn up after due and careful consideration for
the public safety.
When we stop to consider that a film is run
to-day in a theatre where all these very necessary
precautions are taken, and the following day the
same film is sent to some class-room or church, there
to be run by some amateur operator (whose knowl-
edge of projection is limited to the threading
up of the machine and the switching on of the cur-
rent) who is using a projecting machine set up on
the top of some table minus the booth, minus the
various safety devices called for by the authorities,
with probably hundreds of youngsters crowded
around the machine we come to the conclusion that
either too much precaution is taken in the case of
the theatres or not enough in the church and class-
room. We come out here and state that it is the
latter. There are hundreds of churches, schools, and
educational bodies throughout the country which
are using inflammable film without taking the neces-
sary precaution against the ever-present fire risk.
When inflammable film is used, it matters not what
make of projector you are using, you must install
238
MOTION PICTURE PROJECTION
the machine in a fireproof booth that has been ap-
proved by the proper authorities, and an experienced
man should be placed in charge. The law is very
clear and definite on this point.
MOTION PICTURE PROJECTION
SCREENS
The screen has in the past been one of the most
neglected features of the average picture theatre.
He who states that this or that particular screen is
the best in all cases is in the same class with the
country fair medicine vendor who calmly proclaims
that his pill has the virtue of curing all ills from
mange to matrimony.
The sole duty of a screen is to reflect light. We
see the picture on the screen not by the light that
strikes the screen, but by the light which the screen
reflects to the eye. We would not be able to see a
picture projected onto a black screen, for the simple
reason that there would be no light reflected. Then
again, the screen that reflects the most light need not
necessarily be the ideal screen, the manner in which
the light is reflected must be taken into consideration.
There are so many things to consider when choos-
ing a screen for any particular installation that it is
almost impossible to give general information that
can be applied without qualification. The following
are a few of the points that should be considered :
Size and shape of theatre.
Is there a balcony?
Location of the projection room in relation to the
screen.
Layout of seats as regards the viewing angle.
Is the screen to be fixed or movable, and is there
to be light behind it at times?
Distance from screen to nearest row of seats.
Kind and quantity of light to be used in projector
and its source.
240 MOTION PICTURE PROJECTION
Some further points to be borne in mind are these :
No screen reflects all of the light that reaches it be-
cause all materials are more or less absorbent. No
screen can be an efficient direct reflector and at the
same time a satisfactory diffuser of light, as these
two qualities are in direct opposition. In referring
to the two classes of screens, it would probably be
better to speak of one as a direct reflector and the
other as an indirect reflector.
With a given source of light projected at normal,
i. e., from directly in front and viewed from the same
position, the direct reflecting screen will be much
The Largest Motion-Picture Screen Ever Constructed. It
Measured 165 by 135 Feet. A Simplex Type "S" Projector
Using 170 Amperes, With a Throw of 350 Feet Projected a
Picture 100 by 75 Feet
MOTION PICTURE PROJECTION
241
brighter than the indirect reflecting one, but when
viewed from angles the indirect reflector is the
brighter, the difference increasing as the angle in-
creases. To the observers seated rather close to the
screen of average size the picture will be more satis-
factory if an indirect reflector is used, because the
Partially Finished Screen
viewing angle varies considerably for different points
on the screen, and consequently the picture would
not be of uniform brightness if a direct reflector
were used.
Generally, the direct reflecting screens are metallic
surfaced (there are a few exceptions), while the in-
direct reflectors have a non-metallic (mineral or fab-
ric) surface. Metallic surface screens generally show
very contrasty pictures, the high lights being very
242
MOTION PICTURE PROJECTION
bright and glary, and the shadows very deep. There
is a lack of graduation in the toning, however, so
that the picture is deficient in fine detail. The in-
direct reflectors on the other hand are generally not
contrasting because their high lights are subdued,
i. e., not glary, and the shadows are not so deep or
black but the picture is full of half tones, the fine-
ness of which depends largely upon the grain or
weave of the material used and its uniformity.
The maximum in screen value may be summed up
as follows :
Most light from given current consumption or
high reflection and slight absorption of the incident
light. Uniform distribution of the reflected light
over a wide angle without loss of brightness. Detail
and half tones without diminishing contrast clear,
Rear View of World's Largest Screen Showing Tremendous
Amount of Lumber Used
MOTION PICTURE PROJECTION
243
bright "high lights" without glare, absolute opaque-
ness, great durability and ease of transportation and
installation, adaptability to different light sources,
such as arc or incandescent lamps, direct or alter-
nating current.
Since all of these features cannot be incorporated
in anv one screen, it becomes necessary to decide
The Projected Picture Could be Easily Seen Six Blocks Away.
The Screen Was Used at the Methodist Centenary, Colum-
bus, Ohio
which one has the best combination of the above men-
tioned points in accordance with the requirements of
the auditorium being equipped. While the writer
has never made a thorough test of the matter, he is
of the opinion that it is unwise to attempt to decide
the amount of current necessary for a given installa-
tion by considering only the seating capacity of the
house and the size of the screen. The shape of the
244 MOTION PICTURE PROJECTION
auditorium and the arrangement of the seats in rela-
tion to the screen are matters of the utmost impor-
tance when considering not only the amount of illumi-
nation necessary but also the kind of screen upon
which the light is to be projected, because if the
room be wide in proportion to the depth or there is
a deep balcony with the projection room at a con-
siderable elevation, so that there are some seats from
which the viewing angle is greater than 20 or 25 de-
grees of either the axis of projection or of the per-
pendicular face of the screen, or both, it will be neces-
sary to install a screen of the indirect reflecting type
so that the illumination will be distributed over these
wide angles, and since distributing a given amount of
light over a greater area proportionately reduces the
amount of light available per degree, it will be necesi-
sary, if a given screen brightness is to be maintained,
to use more current in a house having rather large
angles than would be used if the angles were not so
great. This does not necessarily mean that as gen-
erally used one class of screen is more costly in the
matter of current than the other. It all depends
upon whether or not the screen is suited to the house.
If, for instance, an indirect reflecting screen is in-
stalled in a long, narrow house, a large proportion
of the light will be reflected toward the side walls and
ceiling and wasted. On the other hand, if a direct
reflector screen be installed in a house that is rather
.wide or where the picture is projected at an angle,
there will be a pronounced "fade-out" or loss of light
from all seats that are not in the direct reflective
angle of the screen. Now, in order to overcome the
fade-out and increase the light to seats outside of
MOTION PICTURE PROJECTION 245
this direct reflective angle, the projectionist usually
increases the incident illumination to a degree far
beyond the amount needed for proper screen bright-
ness, a practice that is not only wasteful as regards
electric current, but produces the glare in the "high
lights" that is extremely unpleasant to the observer
as well as injurious to the eyes.
The screen should be outlined with a dull black
border, and should be placed so that no light save the
light from the projector reaches it. The location of
the screen must be governed by local conditions, but
it is well to see that it is placed high enough so that
the lower part of the picture can be comfortably seen
in all parts of the house, and yet not so high that
those sitting down front have to strain their neck
looking up to the picture. Wherever possible the
screen should be placed so that the center beam of
light strikes the center of the screen at right angles.
By doing this distortion and "keystone effect" will
be overcome.
246 MOTION PICTURE PROJECTION
METHOD AND APPARATUS FOR PROJECT-
ING MOTION PICTURES WITH
COLOR EFFECTS
David Wark Griffith has received from the Com-
missioner of Patents at Washington the exclusive
right to "make, use and vend certain methods and
apparatus for the projection of motion and other
pictures with color effects."
The Griffith patent, granting protection for a
term of seventeen years, was secured by Albert L.
Grey, Mr. Griffith's general manager, through At-
torney O. Ellery Edwards, and will give the producer
ample protection against the copying or appropri-
ating of his lighting effects in color, first introduced
by Mr. Griffith in connection with the showing of
"Broken Blossoms" at the George M. Cohan Theatre,
New York City.
The Griffith patent covers a wide range of light-
ing, including the process and apparatus by means of
which either moving or other pictures may be pro-
jected onto an illuminated screen which has colored
lights blending with the pictures shown. These and
other inventions are covered by the patent, the em-
bodiment of which are as follows:
"The process of producing colored pictures on an
opaque screen, which consists of throwing pictures
by a projector onto one surface of said screen and
simultaneously illuminating the screen with diffused
colored lights thrown onto the same surface of the
screen in a direction oblique to the stream of light
from the projector.
MOTION PICTURE PROJECTION
247
D. W. GRIFFITrf.
ETMOO AND APPARATUS FOR PROJECTING MOVING AND OTHER PICTURES WITH C010B EFFECTS.
1,334,853. Patented Mar, 23, 1920.
2 SNEETS-tHEIT I.
*,
ft 7
7 //
INVENTOR
CQ<
\BY
248
MOTION PICTURE PROJECTION
"In an apparatus of the class described, the fol-
lowing equipment: An opaque screen, a projector, a
bank of colored lights out of the path of light from
said projector and for the purpose of throwing
diffused colored light onto the same, surf ace of said
screen, so that a colored picture is shown when the
apparatus is in use."
Those who saw Mr. Griffith's production of
"Broken Blossoms" during the Griffith repertory
season in New York, will recall the illusive curious
tinted lights that came and went across the surface
of the picture during the unfolding of the story. The
scenes seemed bathed in a vibrant mauve, while the
inner core of the picture itself shimmered with sal-
mon pink. The symbolic blue of the Orient lighted
the Chinese scenes, and gave atmosphere to the por-
tions of the story wherein the Chinaman figured.
Words cannot do justice to the photographic effects,
MOTION PICTURE PROJECTION 249
many of which were like beautiful moving canvasses
colored by an impressionistic touch.
Figure 1 A perspective diagrammatic view of the
preferred embodiment of the Griffith invention.
Figure 2 A sectional view through the bank of
colored lights for throwing direct and diffused col-
ored lights on the screen.
Figure 3 A front elevation of this bank of light.
DESCRIPTION
Figure 2 When the trough (6) is bent, it forms
a suitable reflector, and has suitable glow lamps (8)
mounted therein, one in each compartment, and sup-
plied with electricity from any suitable source by
wires (9).
Figure 3 A long trough (6) has a number of
partitions (7) which divide the space in the trough
into several distinct compartments, so arranged that
light cannot leak from one to another. The front
of the trough is closed by a perforated plate (10)
and each perforation is closed by means of a colored
diaphragm or screen (11).
Figure 4 A diagram of the wires and lights used
with the Griffith invention.
DESCRIPTION
The glow lights (8) have their wires (9) run to
the ordinary main wires, which are designated 12
and 13 for the blue lights, 14 and 15 for the red
lights, and 16 and 17 for the yellow lights.
The blue lights are controlled by a rheostat or
dimmer (18), the red lights by a corresponding in-
strument (19) and the yellow lights by another (20).
The wires (12, 14, 16) run to the bus bar (21)
250 MOTION PICTURE PROJECTION
and the rheostat (18, 19, 20) are connected to the
other bus bar (22). Wires 23 and 24 connect these
bus bars through the projector (4) and its regulator
or rheostat (25).
If electricity be shut off the red and yellow lights,
and turned on the blue lights, the entire screen will
appear blue, and the images from the projector will
be correspondingly colored. Also, by the regulators
or dimmers (18 and 25) the intensity of illumination
of the screen may be varied so that an infinite num-
ber of color effects may be produced with one set
of colored lights.
MOTION PICTURE PROJECTION 251
SIMPLEX-BOYLAN EVEN TENSION REEL
That long neglected yet very important device,
the film reel has at last claimed the attention of the
machine manufacturers. Just how many thousands
of dollars are wasted yearly in film damage due to
defective reels, will be hard to say, but the amount
must be enormous. The pecular part being that the
film exchanges are the worst offenders, sending out
features worth hundreds of dollars on reels that are
in such a condition that the film has to materially
suffer in passing through the projector, or in trans-
portation. The Simplex Machine Co. were quick to
recognize the merits of the reel designed by Grove S.
Boylan, and after incorporating several improve-
ments are now placing the reel on the market as the
Simplex-Boylan Even Tension Reel. The reel is
252 MOTION PICTURE PROJECTION
light in construction yet very strongly made, the
sides are made of cold rolled steel wire, which elimi-
nates all rough sharp edges, saving both the film and
the operators fingers. The hub is of die cast com-
position specially designed to prevent the slightest
chance of inefficiency.
Parts Making Up the Hub of Reel
The weakest part of every reel is naturally the
hub; often a reel has to be discarded after a few
weeks of service owing to the keyway in the hub of
reel having become badly worn, caused generally by
the strain it is called on to bear while the film is
being rewound. It will be seen that with the Sim-
plex-Boylan reel all parts liable to wear are inter-
changeable making it unnecessary to discard the
whole reel should the hub or any part of it become
worn; then again it will be seen by referring to the
diagram that the tension while rewinding is on the
key that engages across the hub, rather than on the
hub itself, thus greatly increasing the life of the
reel.
The premier advantage is that the projector take-
up can be screwed up tight and thus put out of com-
mission, the Simplex-Boylan reel being so constructed
that it will take care of the film tension automatic-
MOTION PICTURE PROJECTION
253
ally ; this it does owing to the friction caused by the
weight of the reel and the film which gives the tension.
The friction between the reel and the hub, automatic-
ally increases as the film is wound on to the hub,
thus giving uniform tension from start to finish of
picture.
Simplex-Boylan Even Tension Reel
254
MOTION PICTURE PROJECTION
Simplex Type "S"
MOTION PICTURE PROJECTION 255
INSTRUCTIONS FOR INSTALLING THE
SIMPLEX PROJECTOR
Unpacking
Upon arrival of the machine use utmost care in
unpacking.
Use nail puller in opening case and removing all
nails used in securing cleats supporting different
part.
Never use a hammer to knock out cleats.
Cleats removed ; parts can be lifted out one by one.
Pay special attention when removing Mechanism
from case.
Don't take hold of shutter shaft to lift it out.
Take hold of bottom with right and top with left
hand thus lifting it out of case.
Unusual strain will bend shutter shaft.
Simplex Machines while simple and strong in con-
struction, are a carefully adjusted piece of mechan-
ism and cannot be handled roughly beyond a certain
limit.
Setting Up Simplex Projector
A. Assemble pedestal column to base.
Have two feet of base face screen.
B. Fasten lower magazine and take-up to base.
Use two screws furnished for the purpose.
C. Fasten mechanism to pedestal top by means of
two wing screws.
D. Attach upper magazine to top of mechanism.
E. Assemble Lamphouse to carriage just back of
Mechanism.
256 MOTION PICTURE PROJECTION
Connecting Up Asbestos Leads
D. C.
Attach three (3) ft. wire to Lamphouse and lower
switch box terminal.
Attach four (4) ft. wire to opposite lower switch
box terminal and to one side of rheostat.
Attach six (6) ft. length to other side of rheostat
and connect other end to upper carbon holder.
A. C.
In connecting transformers or current savers, con-
nect wires from main line switch or wall switch to
upper terminals on pedestal switch. Now connect
two wires from lower terminals on above switch to
primary winding of whatever transforming device is
used, which will be found marked "line." Then con-
nect two wires from terminals marked "lamp" on the
transforming device, after which connect other two
ends of these two wires to the upper and lower carbon
holders inside of lamphouse.
Condenser
Place 61/2 in- condenser toward arc and 7% i* 1 -
toward screen.
Lens Assembly
The flat surface of the moving picture lens should
face the arc; the bevel side the screen. This also
applies to achromatic lenses.
MOTION PICTURE PROJECTION 257
Shutter, Stereo Lens Holder and Framing
Device
Shutter should be placed on shutter shaft in front
of mechanism in accordance with instructions in fol-
lowing pages.
The framing handle should be inserted in framing
device on lower part of mechanism facing lamphouse.
Take lens holder, insert lens between adapters,
tighten with holder ring and fasten to upper part of
mechanism away from operator with stereo rod in-
serted in stereo arm.
Attaching Motor
For the attaching of the Motor Table a slot will
be found on the left of the pedestal column, nuts
and washers for fastening same are furnished.
Two sets of holes will be found on Motor Table,
either set of which may be used according to drive.
When using old style drive in conjunction with
pedestal pulley, use inner set of holes. If motor is
to be used in connection with new speed control, use
the outer set. Two 5/16 in. wing screws are fur-
nished for fastening motor to table. After attaching
motor to table, fasten snap switch to slide over arm
for which three holes are provided. The canvasite
cord attached to the snap switch should then be
connected to the line intended to furnish power for
the motor by means of an attachment plug or other
device. On AC when using constant speed induction
motor furnished with the new friction speed con-
troller, a 10 ampere fuse is recommended, as this
258 MOTION PICTURE PROJECTION
motor requires about three times the normal running
current for starting under full load.
On DC Motors a three ampere fuse is of sufficient
capacity and is recommended for the protection of
the motor.
Lower magazine has a reversible take-up pulley
with two grooves. The large grooves should be used
with the long take-up belt for large reels, 5 in. hub,
taking 1,000 ft. of film or over. The small groove
should be used with the small take-up belt with reels
having small hub. If take-up does not work properly,
reverse pulley, you may have it on wrong.
MOTION PICTURE PROJECTION 259
Simplex Mazda Equipment
262
MOTION PICTURE PROJECTION
against going back on him it must be designed right
in the first place.
Now, there are two ways of designing a Take-up
Shaft.
One way is to design it wrong, to have the belt
pull sideways on the shaft, cramping it in its bear-
ings, and then to try to overcome the difficulty by
introducing ball bearings.
The other way is to design it correct in principle,
like the Simplex Take-up Shaft here illustrated.
When you read the explanations you will quickly
see that the belt-pull doesn't come on the shaft at
all; so there's no cramping or friction to try to
reduce by "anti-friction" bearings.
And, as you know, the probability of any piece
of mechanism going wrong increases directly as the
The Heart of the Simplex
MOTION PICTURE PROJECTION
263
number of parts it contains. So being extremely
simple as well as free from blunders in design, the
Simplex Take-up Shaft is dependable in the highest
decree.
The Intermittent Movement
The Simplex embodies the "star and geneva"
movement, this principle being as highly refined as
is possible to do with the best procurable material
and precision workmanship.
No other intermittent movement has yet been
evolved which compares with the geneva movement
for accuracy, length of wear and yet allows for per-
fect adjustment to compensate for any amount of
wear.
Movement lies in oil chamber, the lubrication for
which is conveyed through .oil tubes easily accessible.
Shafts and sleeve bearings are ground fit, insuring
long service and perfect fit and alignment.
Adjustment of star and cam is made by means of
eccentric bushing and by use of fork wrench without
removing any portion of the mechanism.
Diagram showing progressively the operation of the Geneva
intermittent movement
264 MOTION PICTURE PROJECTION
Complete intermittent unit may be removed en-
tirely and replaced in two minutes, only tools re-
quired for so doing being screw driver and pliers.
Casing is absolutely dust-proof, insuring against
abnormal wear.
All mechansm adjustments that are most generally
used are located within easy reach of the user's left
hand.
1, 2, 3 Are used for making all stereopticon ad-
justments.
4 Focuses the projector lens which is contained
within the mechanism, this method of focusing doing
away with the common practice of reaching in front
of the mechanism to focus lens and the attending
danger while so doing of knocking against revolving
shutter.
5 Indicates knob which locks door cover lower
loop.
Accessibility of Adjustments on Simplex Projector
MOTION PICTURE PROJECTION 265
6 Enables the user to adjust shutter while ma-
chine is in operation, this being an exclusive Simplex
feature.
7 Indicates frame lever so arranged to give per-
fectly balanced leverage with the least possible
exertion.
266 MOTION PICTURE PROJECTION
Simplex Type "B'
MOTION PICTURE PROJECTION 267
VARIABLE SPEED CONTROL
Installation and Operation
When it is desired to change from hand driven
machines to motor driven, simply loosen up the set
screw (three turns) which holds the motor drive
pulley shaft in the lug on the base of the mechanism
frame. The driving shaft on the speed control,
S-575-X (page 314), which has a small gear on it, is
then inserted into the hole in the lug on the base of
the mechanism frame.
In attaching the device, it is very important that
care should be taken to mesh the gear on the shaft
of the speed control S-575-X with the main driving
gear on the mechanism. The set screw should then
be tightened. At the same time, the idler pulley shaft
on the pedestal fits into the opening on the right of
the speed control, and is tightened with the knurled
head or wing screw from underneath, but the set
screw to hold the driving shaft should be fastened
first. Fasten the right end of the speed control at
whatever position it takes on the idler pulley shaft
on the pedestal. Do not force it into position, as
it may cause the gear on the speed control and the
main driving gear, to bind, and eventually ruin them
by wearing unevenly. The important thin is to see
that the two gears mesh properly and the remainder
of the speed control will take the position which will
give best results.
To install the device on motor driven machines
you have to remove the motor drive pulley on the
main driving shaft also the idler pulley on the pedes-
268
MOTION PICTURE PROJECTION
tal shaft. Place the speed control on the machine
in the same manner as described above for changing
from hand driven machines to motor driven.
The present D. C. Motors can be used by making
a slight alteration in them, but in the case of alter-
nating current, a new constant speed induction type
of motor is provided. This abolishes the commutator
type of motor and means lower maintenance costs and
longer life of motors.
The arrangement of the belt for the speed control
is shown in the accompanying illustration Fig. C
better than could be described in a few words. The
illustration amplifies the description for placing the
speed control on the machine.
Fig. C
MOTION PICTURE PROJECTION 269
It may be advisable, however, to give a few details
in connection with the operation of the device.
The variable speed control is operated or con-
trolled by Handle S-438-M (page 314). By turning
this handle either to the left or right, the movement
of it either tightens or releases the Tension
Spring F-119-X and moves the friction disc
S-218-L. This . friction disc S-218-L operates
between the two other discs X-7 and D-118-X.
At any time, it is only the rim of the
friction disc S-218-L that comes in contact
with the other discs X-7 and D-118-X. When the
handle, is turned so that the contact of the friction
disc is near the center of the other discs, the speed
is low because the contact is almost at the center
of the circle of the two discs and revolves on a small
circumference. As the friction disc S-218-L is mov-
ed out near the edge of X-7 and D-118-X the cir-
cumference of the circle increases, and the speed is
correspondingly increased.
It is absolutely necessary, if the friction disc
S-218-L is to drive the control and the mechanism,
that it have a friction contact.
No oil of any description can be used on the fric-
tion discs or the other discs. And further, as oil
may accumulate on these discs from time to time
from the shaft, the discs must be wiped off occasion-
ally. As soon as the oil accumulates, friction is
eliminated, the speed reduced and the device may
stop entirely. A small amount of vaseline may be
applied to the fibre disc occasionally ; it should, how-
ever, be wiped clean after applying.
It also must be borne in mind that the nuts
N-136-X holding the spring on the shaft S-470-X
270
MOTION PICTURE PROJECTION
must not be tightened too much; just enough to
catch the thread sufficiently to hold the spring, as
a very little pressure on the discs is required to run
the control.
PLATE 1
MOTION PICTURE PROJECTION 271
In changing the speed, the idler pulley moves with
the tension spring F-119-X, and adjusts the belt so
that no matter what speed is required, the belt ad-
justs itself to requirements.
THREADING SIMPLEX
To thread the film through the Simplex head, open
up film rollers A and D, Plate 1, open gate by press-
ing plunger B; now draw out of upper magazine
through magazine valve about three feet of film, pass
film under top feed sprocket and close film roller A,
thread through gate, making sure that the film is
riding on runners; engage film on teeth of intermit-
tent sprocket, then close gate by tripping catch C ;
next pass film over lower feed sprocket and close
film rollers D, thread through the lower magazine
valve and engage on clip on lower reel. Care must
be taken to see that a loop of film is formed between
the upper sprocket and gate, and between the inter-
mittent and lower sprocket.
BEFORE STARTING YOUR SHOW
See that
Carbons are long enough to last through the pic-
ture.
Lamphouse is free from grounds.
All electrical c'onnections are tight.
Arc is not burning upside down.
The light spot is focused on aperture in gate.
Projector is oiled, intermittent bath is full, grease
cups are filled and are feeding.
Magazines are lined up with mechanism, so that film
travels in a straight path from top to lower
magazine.
272 MOTION PICTURE PROJECTION
Take-up tension is all right, if using Simplex-Boylan
reels, see that take-up on machine is out of
commission.
Sprockets are free from dirt ; remember that dirt on
the intermittant sprocket may cause jumping
of the picture on the screen.
Tension springs on gate of projector are adjusted
properly.
There is no deposit of emulsion on the tension springs
and shoes.
Light or revolving shutter is synchronised with in-
termittent sprocket.
Reels on which films are wound are in such a condi-
tion that the film runs off same unhampered.
Lenses and condensers are clean.
Picture is in focus, and in frame.
MOTION PICTURE PROJECTION 273
INSTRUCTIONS FOR SETTING UP SIM-
PLEX MAZDA EQUIPMENT
The Condensers
Condensers (J fig. 1) will be found wrapped
with paper covering. Note that sizes of condensers
(6% and 7%) are plainly marked on wrappings.
Unscrew condenser rings (M fig. 1) and drop
condensers into same carefully.
Screw condenser holder ring back in to place se-
curely enough to hold condenser. Great care must
be taken against tightening this ring too firmly, as
by so doing will bind condenser and prevent expan-
sion when same becomes heated, resulting in possible
breakage.
When this has been done condenser holders con-
taining condensers are then dropped into containers
(N fig. 1) with rounded or convex surfaces facing
one another.
Note that the 6% condenser sets in container
nearest the lamp and the 7% condenser sets in con-
tainer nearest the film.
274 MOTION PICTURE PROJECTION
Now swing condenser mount back into position,
locking the same by engaging handle (I fig. 1)
with lock (K fig. 1).
Placing Lamphouse on Machine.
Lamphouse is now placed on swinging table, mak-
ing sure that sliding base (P fig. 1) sets accurately
into base groove (Q fig. 1), then fasten lamphouse
to base with wing screw (R fig. 1).
Setting Lamp in Holder.
Loosen knob (H fig. 1), turning same out to its
fullest extent, then screw lamp (O fig. 1) into its
socket, as far as possible.
Adjust lamp so that filament (T fig. 2) is paralr
lei with knob (F fig. 2). This lining up of filament
is imperative and absolutely necessary in procuring
correct focus, as will be later described.
When proper alignment has been made, tighten
knob ( H fig. 1 ) firmly ; this operating rigidly se-
cures lamp into required position (see illustration,
fig. 4).
MOTION PICTURE PROJECTION 275
Inserting Lamp and Holder into Mechanism.
Lamp and holder are now ready for inserting into
lamphouse.
Hold knob (F fig. 4) and thumb piece (S fig.
4) securely between thumb and forefinger of the
right hand.
Insert lamp slowly into position, making sure that
collar (U fig. 4) engages with rod (U-l fig. 6),
and also note that contact strip (V fig. 5) engages
between slot and contact holder (W fig. 5), push-
ing in as far as it will go.
Inserting Mirror.
We have now reached that stage where the mirror
plays an important part in our system.
Clean and polish mirror carefully with clean soft
tissue paper.
Now loosen thumb screws (X fig. 2) and insert
mirror (L fig. 1) carefully into holder (Y fig. 2),
tightening thumb screws (X fig. 2) only sufficiently
to hold mirror in place without undue pressure.
'
Focusing Mirror.
The distance from the center or back of convex
surface of mirror and the filament (T-2) of the lamp
should be approximately five inches, as shown in
Optical Diagram (page 276).
This distance is obtained by operating knob (A-l)
either to the right or left as occasion may require.
Now unlock mirror holder by turning knob (D-l)
to the left.
Now swing mirror to one side as far as possible
by means of knob (C-l) and lock same into position
MOTION PICTURE PROJECTION
MOTION PICTURE PROJECTION
by turning knob ( D-l ) to right. This throwing
mirror to one side is done in order to prevent mir
image from being confused with lamp filament, as '
be described later.
PLATE 4
Focal Distances.
Attention is now called to the Optical Diagr
(page 276), which shows the approximate distan
to be used as a basis of operation between the miri
the condensers and the cooling plate of the machi
278
MOTION PICTURE PROJECTION
~n
MOTION PICTURE PROJECTION 279
Should a quarter size (!%" diameter) projector
lens be used it is now necessary to place ruler against
the surface of the 7^2 i nc ^ (front) condenser and
move lamphouse slowly forward or backward until
a distance of nine inches separates the front con-
denser surface from the film position or aperture
plate on mechanism.
Should the half size (2%" diameter) projector
lens be used, this distance should be increased to
eleven inches.
Adjusting Lamp.
Turn knob (B fig. 1), which is used to carry
lamp carriage forward and backward, until lamp
filament (T fig. 2) is 3% inches away from flat
surface of 6^/2 (rear) condenser.
Connecting Up Apparatus.
(For alternating current)
We are now ready to connect the apparatus with
regulator, as designated in diagram marked "A. C.
Wiring Diagram" (page 278).
Note that this diagram is based on voltages rang-
ing from 95 to 120 inclusive.
It will be noted that the ammeter for registering
lamp amperage will be found packed separately in
carton which comes in lamphouse shipping case.
This ammeter is to be attached to bracket on rear
of lamphouse, as designated in A. C. Wiring diagram,
by means of screws located in bracket.
Warning In no case should ammeter be placed
onto regulator, as it will not register properly in this
location, owing to electrical disturbances.
280
MOTION PICTURE PROJECTION
wJu><.J*.J>
MOTION PICTURE PROJECTION 297
SIMPLEX PARTS
(HEAD)
Name
S-436-A Focusing Knob Set Screw.
R-178-A Focusing Knob Rod.
K-119-A Focusing Pinion Rod Knob.
S-125-A Eccentric Bushing Screw.
W-145-D Upper Feed Sprocket.
S-134-E Film Trap Door Stud Screw.
S-106-E Right Back Cover Latch Plate Screws.
L-116-B Intermittent Case Cover Lock.
S-157-B Intermittent Case Cover Lock Screw.
A-117-A Picture Framing Arm.
L-114-G Picture Framing Connecting Link.
K-120- A Shutter Adjusting Screw Knob.
S-125- A Shutter Adjusting Screw Knob Set Screw.
C-ll Framing Handle Complete.
S-252-A Shutter Adjusting Screw.
L-107-G Picture Framing Lever.
A-118-G Picture Framing Handle Arm.
N-119-GPicture Framing Lever Pivot Screw Nut.
W-146-D Lower Feed Sprocket.
S-429-G Lower Sprocket Shaft.
S-125-D Eccentric Bushing Screw.
S-189-W Magazine Bracket Screw.
S-573-D Upper & Lower Stripper Studs.
S-572-D Upper & Lower Stripper.
S-445-G Upper Sprocket Shaft.
S-165-A Pad Roller Arm Washer Screw.
A-4 Projecting Lens Holder & Slide.
S-574-G Shutter Shaft.
S-192-D Shutter Spider Screws.
B-122-G Shutter Gear ' Bracket.
S-570-C Upper Pad Roller Arm Spring.
S-342-C Projecting Lens Holder Slide Rod Spring.
C-192-G Intermediate Shaft Retaining Collar.
S-223-G Framing Slide Lever Stud Set Screw.
S-323-A Shutter Adjusting Slide.
S-253-A Shutter Adjusting Slide Set Screw.
S-569-C Lower Pad Roller Arm Spring.
S-572-D Upper and Lower Stripper.
D-l Driving Handle Compete.
S-573-D Upper & Lower Stripper Stud.
298
MOTION PICTURE PROJECTION
W-I26-D
R-5
OIL
S-5I2-B
C-IOO-A
S-34K3
N-II9-G
S-II5 A
B-I98-A
PLATE 4
MOTION PICTURE PROJECTION 299
SIMPLEX PARTS
(HEAD)
Name
S-264-D Stereo Lens Adjusting Screw.
S-155-R Stereo Universal Clamp Wing Screw.
S-106-D Stereo Slide Stop Screw.
A-122-D Stereo Arm.
S-155-R Stereo Universal Clamp Wing Screw.
R-127-R Stereo Lens Adjusting Rod.
R-6 Stereo Lens Holder Universal Clamp.
S-432-E Film Trap Shoe Screw.
W-126-D Governor Weight.
R-5 Stereo Lens Holder.
S-512-B Fly Wheel Set Screw.
C-100-A Framing Cam.
S-341-G Picture Framing Handle Friction Spring.
N-119-G Picture Framing Lever Pivot Screw Nut.
S-115-A Centre Frame Screw.
B-198-A Mechanism Base.
K-102-A Focusing Pinion Knob.
S-324-D Stereo Slide.
S-l 92-D Film Shutter Screw.
S-337-E Lateral Guide Roller Spring.
S-292-E Lateral Guide Roller Shaft.
R-130-E Lateral Guide Roller.
S-161-E Auto. Fire Shutter Stop Screw.
E-l Film Trap Complete.
S-l 02-E Auto. Fire Shutter Link- Retain Screw.
E-7 Auto. Fire Shutter Lift Lever.
L-109-E Auto. Fire Shutter Lift Link.
S-100-E Auto. Fire Shutter Lever Screw.
E-5 Film Heat Shield Complete.
S-138-E Film Trap Heat Shield Retain Screw.
S-316-E Auto. Fire Shutter.
P-263-E Right Back Over Latch Plate.
W-131-B Intermittent Sprocket.
P-153-B Intermittent Sprocket Taper Pin.
S-125-B Eccentric Bushing Screw.
S-124-D Driving Arm Retain Screw.
P-209-D Driving Arm Retaining Plug.
S-287-A Handle Shaft.
R-133-A Framing Cam Adjusting Ring.
C-189-A Handle Shaft Driving Collar.
F-100-A Centre Frame.
302
MOTION PICTURE PROJECTION
a a 9 ? 9 ? V 9 V y V
O
MOTION PICTURE PROJECTION 303
SIMPLEX PARTS
(HEAD)
Name
D-ll Left Door and Knob Complete.
P-144-D Left Door Lock Pin.
S-178-D Left Door Knob Screw.
C-151-D Left Back Cover.
D-19 Lower Left Door Hinge.
D-12 Lojver Left Door Complete.
D-8 Right Back Cover Latch Knob Complete.
S-361-D Intermittent Sprocket Stripper.
S-185-D Lock Stop Screw.
D-9 Right Back Cover Complete.
D-7 Right Back Cover Hinge Complete.
E-101-D Medium Size Escutcheon.
B-198-A Mechanism Base.
p_207-D Top Plate.
C-8 Upper Magazine Roller Holder Complete.
S-181-D Left Door Stop Link Screw.
L-113-D Left Door Stop Link.
C-152-D Left Front Cover.
C-118-D Bevel Glass Clamp.
S-l 92-D Right and Left Door Hinge Screw.
D-18 Upper Left Door Hinge.
G-124-D Right Door Glass.
D-17 Right Door Hinge.
C-159-C Right Front Cover.
D-5 Right Door and Knob Complete.
C-118-D Bevel Glass Clamp.
D-6 Right Door Lock Spring and Button.
S-l 65-C Cover Screw.
C-157-C Right Cover.
R-161-C Large Magazine Roller.
R-160-u Small Magazine Roller.
S-485-C Magazine Roller Screw.
304 MOTION PICTURE PROJECTION
a d. 6 6
or & oro
.2 * J2 "T &ov
MOTION PICTURE PROJECTION 311
SIMPLEX PARTS
(MAGAZINE)
Name
P-235-U Magazine Hinge Pin.
P-236-U Magazine Wire Glass Retaining Plate.
G-131-U Lower Magazine Door Wire Glass.
S-427-U Magazine Wire Glass Retaining Plate Screw.
N-135-U Magazine Wire Glass Retainer Plate Nut.
K-106-D Lower Magazine Door Knob.
C-184-W Lower Magazine Cover 16".
H-143-U Magazine Hinge.
S-138-E Magazine Latch Spring Retain Screw.
P-237-U Magazine Latch Spring Protector.
U-l Magazine Latch.
R-4 Take-Up Belt for Reels with Small Hubs.
H-132-R Belt Hook.
W-l Lower Magazine Roller , Holder.
S-189-W Magazine Arm Screw.
C-182-W Lower Magazine 16".
A-135-W Lower Magazine Arm 16".
N-132-U Magazine Latch Spring Retaining Nut.
P-234-U Magazine Latch Spring Distance Piece.
R-10 Take-Up Friction Belt for Reels with Large Hubs.
S-187-W Lower Magazine Hinge Screw.
312 MOTION PICTURE PROJECTION
MOTION PICTURE PROJECTION 313
SIMPLEX PARTS
(MOTOR)
Name
C-162-S Outlet Box Cover with Switch Bridge.
S-389-S Snap Switch.
B-136-S y 2 " T. & B. Bushing.
B-123-S Snap Switch Bracket.
S-108-S Binding Post Cover Fastening Screw.
C-210-S Canvasite Cord.
S-238-G Switch Box Bracket Fastening Screw.
H-127-S Snap Switch Holder.
S-148-G Motor Pulley Screw.
N-117-S Motor Table Attachment Bolt Nut.
W-116-S Motor Table Attachment Bolt Washer.
B-110-S Motor Table Attachment Bolt.
T-118-L Motor Table.
P-294-X Motor Pulley.
C-209-S Armored Cable.
C-140-S %" Squeeze Connectors.
S-170-R Motor Fastening Screw.
314
MOTION PICTURE PROJECTION
C-2II-X
S-437-G
S-438-M
K-H7-X
R-I66-X
PLATE 12
MOTION PICTURE PROJECTION' 315
SIMPLEX PARTS
(SPEED REGULATOR)
Name
S-178-X Friction Disc Carrier Stop Screw.
G-141-X Speed Adjusting Gear.
S-487-G Collar Set Screw.
W-103-D Starting Rod Friction Spring Retaining Washer.
S-524-X Starting Rod Friction Spring.
C-204-X Starting Mechanism Friction Disc Carrier.
R-168-X Square Rod for Horizontal Handle.
N-186-X Friction Spring Nut.
S-470-X Friction Spring.
S-463-X Internal Friction Disc Driving Flange Set Screw.
S-218-L Set Screw.
F-119-X Speed Control Main Frame.
G-141-X Speed Adjusting Gear.
S-437-G Gear Set Screw.
S-218-I^-Carrier Set Screw.
C-211-X Starting Knob Rod Collar.
S-437-G Gear Set Screw.
S-438-M Starting Knob Set Screw.
K-117-X Speed Control Knob.
R-166-X Starting Knob Rod.
X-7 External Friction Disc Complete.
D-118-X Internal Friction Disc.
X-ll Speed Control Main Pulley and Oil Cup.
S-575-X Speed Control Motor Pinion Stud.
X-5 Tension Pulley Carrier Complete.
S-438-M Speed Control Knob Set Screw.
X-8 Idler Pulley Carrier Complete.
316
MOTION PICTURE PROJECTION
B-207-:
D-II4-X
PLATE 13
MOTION PICTURE PROJECTION 317
SIMPLEX PARTS
(SPEED REGULATOR)
Name
B-207-X Speed Control Belt.
S-469-X Tension Pulley Carrier Roller Screw.
R-153-X Tension Pulley Carrier Roller.
S-472-X Square Rod Friction Spring.
S-173-X Friction Spring Screw.
S-467-X Main Frame Clamp Screw.
S-145-G Pulley Carrier Screw.
D-114-X Starting Mechanism Friction Disc.
X-ll Speed Control Main Pulley and Oil Cup.
X-8 Speed Control Friction Disc.
S-218-L Set Screw.
S-471-X Belt Tension Spring.
K-117-X Speed Control Knob.
R-165-X Speed Adjusting Knob Rod.
W-107-G Pulley Washer.
P-293-X Deflecting Pulley.
31-
MOTION PICTURE PROJECTION'
MOTION' PICTURE PROJECTION
SIMPLEX PARTS
(PEDESTAL)
ffi
S-270-L Switch Box Screw.
C-105-L Lampboose Carriage.
S-103-F Lamphouse Carriage Handle Fastening Screw.
S-3ST-L Knife Switch 60 Amperes.
5-52 -L Auxiliary Arm Pivot Screw.
H-148-L Lamphouse Carriage Handle.
W-iia-L Lamphouse Carriage Washer.
S-37-5-L Lampbouse Carriage Pivot Stud.
L-3 Switch, Box and COTCT Complete for 60 Amperes.
L-o Switch, Box and Cover Complete for 100 Amperes.
A-120-L Slide Over Arm.
Q-100-L Quadrant.
S-172-L Lamphouse Carriage Retain Screw.
P-197-L Slide Over Arm Pivot
A-116-L Pedestal Arm.
P-256-L Pedestal Arm Pivot.
S-218-L Pedestal Arm Pivot Set Screw.
S-520-L Auxiliary Arm Pivot Screw.
A-107-L Auxiliary Arm.
S-229-L Quadrant Lock Retaining Screw.
C-137-L Pedestal Column.
L-117-L Quadrant Lock.
S-230-L Quadrant Stand Screw.
L-2 Quadrant Lock Clamp Handle and Set Screw.
L-l Pedestal Stand Handle and Set Screw Complete.
S-355-L Pedestal Stand.
PflM
322 MOTION PICTURE PROJECTION
S-3I5-M
P-3
PLATE 16
MOTION PICTURE PROJECTION 323
SIMPLEX PARTS
(REWINDER)
Name
"M" Rewinder Bracket Complete.
S-438-M Rewinder Set Screw.
G-114-M Rewinder Spur Gear.
M-3 Rewinder Handle.
N-108-M Internal Gear Shaft Nut.
M-l Internal Gear & Shaft (Includes C-128-M, S-438-M.)
M-6 Rewinder Reel Shaft and Locks.
C-128-M Internal Gear Shaft Collar.
B-120-M Rewinder Bracket.
S-315-M Rewinder Fastening Screw Shoe.
P-3 Rewinder Fastening Screw Complete.
324
MOTION PICTURE PROJECTION
R-142
F-I09-Q
S-522-Q
*-i4i-Q
PLATE 17
Name
C-1T5-Q Collar for %" Shaft.
G-128-Q Spiral Gear for %" Shaft.
S-398-Q Contact Piece Connection Screw.
P-224-Q Contact Piece for Top Carbon.
R-143-Q Upper Carbon Secondary Guide Rod.
C-173-Q Upper Carbon Clamp.
J-101-Q Upper Carbon Jaw.
F-113-Q Upper Carbon Secondary Sliding Frame.
MOTION PICTURE PROJECTION 325
F-112-Q Upper Carbon Main Sliding Frame.
S-218-L Set Screw.
R-144-Q Upper and Lower Carbon Frame Guide Rod.
W-139-Q Insulating Washer.
N-130-Q Upper Carbon Contact Piece Retain Nut.
P-223-Q Contact Piece for Lower Carbon.
C-172-Q Lower Carbon Clamp.
J-100-Q Lower Carbon Jaw.
F-108-Q Lower Carbon Secondary Sliding Frame.
R-174-Q Lower Carbon Cross Feed Sliding Rod.
F-104-Q Burner Cross Feed Sliding Frame.
S-394-Q Carbon Feed Screw.
B-139-Q Burner Base.
S-218-Q Headless Set Screw.
R-142-Q Main Sliding Frame Guide Rod.
PM09-Q Lower Frame Casting of 3rd Sliding Frame.
S-522-Q Screw for Vertical Adjustment of Arc.
S-414-Q Driving Shaft in Top Frame.
P-261-Q Universal Joint Cotter Pin.
J-102-Q Universal Joint.
R-171-Q Universal Joint Rivot.
R-138-Q Handle Rod 10".
R-144t-Q Upper and Lower Carbon Frame Guide Rod.
F-114-Q Top Frame Casting of 3rd Sliding Frame.
S-523-Q Screw for Top Carbon Longitudinal Adjustment.
C-175-Q Screw for Top Carbon Longitudinal Adjustment.
C-175-Q Collar for %" Shaft.
J-102-Q Universal Joint.
G-128-Q Spiral Gear for %" Shaft.
R-137-Q Handle Rod 9".
S-411-Q Driving Shaft in Lower Carbon Frame.
R-138-Q -Handle Rod 10".
S-218-L Set Screw.
R-136-Q Handle Rod 8".
R-174-Q Lower Carbon Cross Feed Sliding Rod.
R-139-Q Handle Rod 10M>".
S-412-Q Driving Shaft in Lower Carbon Frame.
C-175-Q Collar for %" Shaft.
Q-16 Horizontal Longitudinal Adjustment of Arc Screw.
C-176-Q Collar for %" Shaft.
S-521-Q Screw for Crosswise Adjustment of Arc.
F-110-Q Main Sliding Frame.
R-141-Q Main Cross Feed Sliding Rod.
326
MOTION PICTURE PROJECTION
COJL n u,
2$8*? a $2 S!C:
Z O) CO O CD O O.Z Q. U
MOTION PICTURE PROJECTION 327
SIMPLEX PARTS
(ARC LAMP)
Name
R-144-Q Upper and Lower Carbon Frame Guide Rod.
H-138-Q Large Fibre Handle.
H-139-Q Small Fibre Handle.
G-129-Q Spiral Gear for %" Shaft.
G-128-Q Spiral Gear for %" Shaft.
F-103-Q Handle Flange.
S-398-Q Contact Piece Connection Screw.
N-130-Q Upper Carbon Contact Piece Retain Nut.
N-131-Q Upper Carbon Clamp Nut.
S-394-Q Carbon Feed Screw.
S-522-Q Vertical Adjustment of Arc Screw.
G-128-Q Spiral Gear for %" Shaft.
B-196-Q Carbon Jaw Bolt.
G-129-Q Spiral Gear for y 2 " Shaft.
P-228-Q Lower Carbon Stop Pin.
N-141-Q Lower Carbon Clamp Nut.
P-123-B Taper Pin.
C-175-Q Collar for %" Shaft.
328 MOTION PICTURE PROJECTION
N-II8-F
S-I86-F
L-I02-F
PLATE 19
MOTION PICTURE PROJECTION 329
: SIMPLEX PARTS
(ARC LAMP)
Name
N-118-F Carbon Feed Bracket Support Screw Nut.
L-102-F Carbon Jaw Tilt Screw Lever.
S-186-F Lower Carbon Holder Wing Screw.
330
MOTION PICTURE PROJECTION
C-I97-F
W-I53-F
R-I72-F
C-227-F
B-I70-F
S-555-F
W-III-F
B-M5-F
PLATE 20
S-113-F Carbon Holder Clamp Screw.
W-101-F Carbon Holder Washer.
S-148-F Set Screw.
B-114-F Carbon Holder Bracket.
P-245-F Upper Carbon Tilt Screw Cotter Pin.
B-152-F Upper Carbon Feed Rack (Sub-Bracket).
F-9 Upper Carbon Feed Rack Support.
F-4 Upper Carbon Feed Rack Bracket Adjusting Screw.
J-103-F Upper Carbon Tilt Screw Universal Joint.
N-4 Feed Knob.
S-164-A Tension Spring Screw.
S-335-F Lamp Adjusting Gear Friction Spring.
S-452-F Upper Carbon Tilt Screw Adjusting Shaft.
N-4 Feed Knob. -
S-127-N Feed Knob Hub Screw.
MOTION PICTURE PROJECTION 331
N-2 Carbon Feed Bracket Tilt Screw Knob.
F-5 Carbon Feed Bracket Tilt Screw.
F-7 Carbon Feed Bracket Support.
N-3 Feed Knob.
N-l Feed Knob.
F-l Carbon Feed Gear and Shaft.
S-556-F Lamp Lateral Screw Shaft.
N-l Feed Knob.
N-3 Feed Knob.
S-516-F Lamp Carriage Screw.
S-290-F Lamp Adjusting Gear Shaft.
S-113-F Carbon Holder Clamp Screw.
F-2 Lamp Adjusting Bracket Plate and Pins.
S-164-A Lamp Adjusting Friction Spring Screw.
P-lll-F Carbon Holder Pin.
F-10 Upper Carbon Holder.
L-128-F Carbon Jaw Tilt Screw Lever.
S-439-F Upper Carbon Jaw Tilt Screw.
P-245-F Upper Carbon Tilt Screw Cotter Pin.
B-113-F Carbon Feed Bracket.
P-199-F Carbon Feed Bracket Plate.
S-103-F Carbon Feed Bracket Plate Screw.
S-110-F Carbon Feed Bracket Support Screw.
H-100-F Carbon Jaw Tilt Screw Handle.
S-148-F Set Screw.
S-H4-F Carbon Jaw Tilt Screw.
S-186-F Lower Carbon Holder Wing Screw.
F-12 Carbon Holder Bracket.
W-102-F Carbon Holder Mica Washer.
W-123-F Upper Carbon Feed Rack Sub-Bracket Washer.
S-112-F Carbon Holder Bracket Screw.
F-l 1 Lower Carbon Holder.
WM01-F Carbon Holder Washer.
S-113-F Carbon Holder Clamp Screw.
M-100-F Carbon Holder Sheet Mica.
F-8 Lower Carbon Feed Rack Bracket.
S-438-M Set Screw.
C-197-F Lamp Carriage Screw Collar.
W-153-F Lamp Carriage Screw Washer.
R-172-F Lamp Carriage Guide Rod.
C-227-F Lamp Carriage.
B-170-F Burner Support Bracket.
S-555-F -Lamp Adjusting Plate Tension Spring.
W-lll-F Lamp Adjusting Plate Washer.
B-115-F Lamp Adjusting Bracket.
332
MOTION PICTURE PROJECTION
DYNAMOS
A dynamo electric machine is a device for convert-
ing mechanical energy into electric energy. The word
dynamo is generally understood to mean a machine
for converting mechanical energy into electrical en-
ergy, and the word motor means a machine for con-
verting electric energy into mechanical energy, the
essential parts of a dynamo and motor are the same,
namely the armature and field magnet.
Dynamos are divided into two general classes, ac-
cording to the character of the current they deliver.
A direct current dynamo delivering a current that
always flows in one direction, that is, the current
never reverses, though it may change in value or
pulsate.
Alternating current dynamos or alternators, de-
100 K.W. Engine-Type Generator and Automatic High-
Speed Engine
MOTION PICTURE PROJECTION
liver a current that periodically reverses its direction
of flow, the number of reversals per second depending
on the number of poles in the dynamo and on the
speed of rotation.
A direct current dynamo usually consists of a se-
ries of conductors arranged on the surface of a
cylindrical iron core or in slots near the surface, the
conductors in most cases being parallel with the axis
of the core.
The core is mounted on a shaft that is supported
on bearings so that the armature can be rotated near
the pole faces of a field magnet. This magnet is
excited by one or more field coils. Any even number
of poles may be used according to the size and type
of machine.
The principal parts of a dynamo are: armature
core, bands on armature core, commutator, shaft,
field coils, pole faces, brushes, rear end bearing, front
end bearing, rear end journal, front end journal, ter-
minal block and bedplate.
LINE PUSES
ISAM PS. TOR 1 10 VOLTS
10 220 -
5 - - 550
CURRENT AT ARC
IS ADJUSTABLE
FROM 2O TO
334 MOTION PICTURE PROJECTION
FORT WAYNE A. C. TO D. C. COMPENSARCS
The A. C. to the D. C. Compensarcs is what is
commonly known as a motor generator set, that is,
two machines, a generator and a motor coupled
together and mounted on a common base.
The sets are shipped -completely assembled and
require only proper installation, filling of the bear-
ings with oil and proper connections to the supply
and lamp circuits before putting into service. It
should be understood that these compensarcs are
special machines for use only on picture projection
arcs and cannot be used for ordinary constant volt-
age purposes.
The complete equipment consists of the A. C. to
D. C. compensarc proper, two short-circuiting
switches, one for each picture machine, and the
panel on which is mounted the instrument and field
control rheostat. All single-phase outfits are
equipped with proper starter; for the larger multi-
phase outfits a starting compensator is furnished.
The A. C. to D. C. Compensarc should be installed
in a clean, dry, well ventilated location, and, if pos-
sible, near to the lamps which it is to operate. Often-
times a small room adjoining the projection room is
provided for the Compensarc ; but in some cases
where such arrangements cannot be made the machine
is installed in the basement of the theatre. Inacces-
sible locations should be avoided, as such locations
will result in the machines being neglected, allowed
to become dirty and perhaps damaged.
It is not necessary to provide foundations for these
MOTION PICTURE PROJECTION
compensarcs, but the floor on which they are placed
should be firm and free from vibration.
The machines are clamped to a pair of wooden
skids, which form a foundation for the boxing.
A. C. TO D. C. COMPENSARC
.LINE.
3 PHASE
BACK OF BOQRD.
Fig. 1
Connection Diagram for 35-Ampere Lamp Outfit
MOTION PICTURE PROJECTION
The machine should if possible be left attached
to these skids until it has been conveyed to the loca-
tion which it is finally to occupy. It is preferable
that all wiring should be done before the boxing is
removed from the machine, as the boxing will be
effective in keeping the machine clean.
As soon as the machine is unboxed, the name plate
should be inspected to see that the volts, cycles and
phases marked on the name plate of the motor agree
with those of the circuit on which the machine is to
be used. The name of the generator marking also
indicates the volts and amperes which the generator
is designed to deliver, and the rating should agree
with that specified on the order. It should be re-
membered that the direct-current arc for motion
picture projection requires less current than the
alternating-current arc, 25 to 35 amperes at 55 volts
being usual for the D. C. arc, corresponding to 40
to 60 amperes at 35 volts for the alternating-current
arc.
The A. C. to D. C. Compensarc should be run
only on circuits where the variation of either fre-
quency or voltage from normal does not exceed five
per cent. Where both frequency and voltage vary,
the sum of the variation must not exceed eight per
cent.
If for any reason the generator or motor must be
taken from the base in order to install the com-
pensarc, great care should be exercised that the
machines are properly lined to give a uniform air
gap when the compensarc is reassembled. If this
is not done, trouble will occur due to the set being
out of line. Dowell pins are provided on the gen-
MOTION PICTURE PROJECTION
337
erator end. To remove these hold the squared head
of the pin with a wrench and tighten up the nut
which will pull out the pin. Be careful that any
liners found under the feet are carefully replaced
LINE
3 PHASE
A. C. TO D. C. COMPENSARCS
VIE *V FROM
BACK OF BOARD
Fig. 2
Connection Diagram for the 50 and the 70-Ampere Lamp Outfit
338 MOTION PICTURE PROJECTION
in their proper place. Should the coupling be
taken apart, it must be assembled carefully, making
sure that the halves fit properly.
Diagram Fig. 1 shows the external connections
for the 35 amperes two-lamp series outfit. Fig. 2
shows the external connections for the 50 and 70-
ampere two-lamp series outfit, using only a switch
between the line and the motor end of the machine
on the two-phase and three-phase circuits. The use
of a double throw switch having one side fused for
running and the other unfused for starting is gen-
erally acceptable to the power companies for motors
of five horse-power and smaller. If the power com-
panies or the local conditions require a starting
compensarc, the motor end of the two and three-
phase compensarc should be connected to the line
in accordance with the diagrams Fig. 3 and Fig. 4
respectively.
The wiring should be of sufficient size so that the
line drop from the machine to the lamp will not
exceed one volt, or two per cent of the voltage when
the machine is delivering full-load current to the
lamp. If too small a wire is used the lamp will be
robbed of some of its voltage and give poor light.
The lamp side of these machines does not require
fuses, as the generators are so constructed that they
will protect themselves against overload current
when the arcs are short circuited. The motor side
of the various machines should be fused as follows:
MOTION PICTURE PROJECTION
339
Two
Two
Two
35-ampere
Lamps
50-ampere
Lamps
70-ampere
Lamps
Alternately
Alternately
Alternately
Fuses
Fuses
Fuses
Single-phase 110- volt. . .
Single-phase 220- volt . . .
Two-phase 110- volt. . .
Two-phase 220- volt . . .
Three-phase 110- volt. . .
Three-phase 220-volt.. .
80-ampere
40-ampere
40-ampere
20-ampere
50-ampere
25-ampere
100- ampere
50-ampere
60-ampere
30-ampere
75-ampere
35-ampere
120-ampere
60-ampere
70-ampere
35-ampere
80-ampere
40-ampere
A. C. TO D. C. COMPENSARCS
Fig. 3
Connections of Motor End of A. C. to D. C.
Compensarc When Compensator Is Used on Three-phase
Circuits
340 MOTION PICTURE PROJECTION
Before starting the set see that it is perfectly clean
and that the brushes move freely in their holders and
make good contact with the commutator. Be sure
that the oil wells are clean and filled. These ma-
chines have overflow gauges with hinged caps. The
oil wells should be filled through the overflow gauges
rather than through the hinged covers in the bear-
ings. This method will prevent waste and annoyance
from overflowing of the oil reservoirs. Pour in
enough oil to show in the gauges, the thin oil fur-
nished for the moving picture machine, sewing ma-
chine oil and similar light oils are not heavy enough.
It is better to purchase a can of "light dynamo oil"
and keep it for the compensarc.
See that the armature turns freely in the bearings
and that the machine is level.
Make sure that all the connections are tight and
correspond with the diagram of connections for the
outfit supplied.
When starting up see that the armature starts to
rotate in the direction marked on the coupling. The
direction of rotation of two-phase motors can be
reversed by interchanging two line leads of the same
phase. In the case of single and three-phase motors
it is only necessary to interchange any two line leads
of the motor. Immediately after starting, see that
the oil rings revolve and carry the oil up to the shaft.
Always keep the oil at the proper level in the well,
that is, nearly to the lip of the overflow gauge.
MOTION PICTURE PROJECTION
341
STARTING THE COMPENSARC
In starting up the A. C. to D. C. Compensarc,
have the switches at the lamps open. If a single-
phase outfit, close the main switch and move the
starting arm on the starting box from the "off"
position to the split segment which will introduce
the necessary starting coils to cause the armature
to start to rotate. When the armature has attained
nearly full speed, the starting arm should be moved
quicldy over to the' last segment where it is held by
a latch controlled by a relay magnet. If the voltage
fails, the relay magnet will release the latch, allow-
A. C. TO D. C. COMPENSARCS
Fig. 4
Connections of Motor End of A. C. to D. C. Compensarc When
Compensator Is used on Two-phase Circuits
342 MOTION PICTURE PROJECTION
ing the starting arm to automatically return to the
"off" position stopping the motor.
The arm of the starting box should never be left
in starting position longer than one minute, usually
much less time will suffice. When the power com-
panies do not require the use of starting compensa-
tors in connection with the two and three-phase out-
fits they should be equipped with double-throw start-
ing switches which have only one side fused.
When starting up, the switch should be closed
to the unfused side. When the speed of the arma-
ture is up to normal the switch should be quickly
changed to the running side (fused side).
To start up an A. C. to D. C. Compensarc where
a starting compensator is used, see that compensator
arm is in the "off" position and close the main switch.
The compensator should be thrown into the starting
position with a quick, firm thrust and held there until
the machine comes up to speed (about 20 or 30
seconds), and then with one quick firm movement the
arm should be pulled over into the running position,
where it is held by a lever engaging with the low-
voltage release mechanism.
Never, in any case, should the motor be started
by "touching," that is, by throwing the starting arm
into the starting position and quickly pulling it out
a number of times. Such a plan of "touching" does
not make the rush of current at starting less, but, on
the contrary, it produces a number of successive
rushes in place of the one which it has been attempted
to avoid, and, what is often a more serious matter,
causes the contact fingers to be so badly burned that
it is necessary to replace them. To stop the ma-
MOTION PICTURE PROJECTION 343
chine open the main switch. The compensator arm
should automatically return to the "off" position
on the opening of the main switch; if it does not,
throw it over to the "off" position by hand.
STARTING FIRST LAMP
When the speed of the machine is up to normal
and the starting box or switch is in running position
and the rheostat handle set as marked by the white
arrow, short-circuit the one lamp by means of its
short-circuiting switch. Then close the lamp switch
and bring the carbons together so that they barely
touch; then separate them about 1-16 of an inch,
gradually increasing the separation as carbons heat
up until the proper length of arc is reached. The
D. C. arc should be from 5-16 to 3-8 of an inch
long or about twice as long as an A. C. arc. Adjust
the generator field rheostat until the proper amount
of current is flowing. If the carbons are held to-
gether too long the machine voltage will be auto-
matically reduced to zero, so that the arc will not
have sufficient voltage, and will therefor break when
the carbons are separated. Should this occur, keep
the carbons apart about 10 seconds until the machine
voltage can automatically build up again, then strike
the arc as directed above.
The switchboard panel, having instruments mount-
ed on it along with the field rheostat, is very useful,
and the proper current can at all times be accurately
maintained. As the machine warms up, the handle of
the rheostat may have to be moved one or two but-
tons from the mark to maintain the desired voltage
and current. If the circuits are all connected as
344 MOTION PICTURE PROJECTION
shown in the diagram, the polarity should be as in-
dicated, the upper carbon being positive. Should
the upper carbon be negative and the instrument on
the panel board read backward, the trouble must be
corrected. See that all connections are made as
indicated on the diagram. The polarity must come
correct if the connections are made in accordance
with the diagram of connections, and the armature
of the set rotates in the direction marked on the
coupling.
STARTING THE SECOND LAMP
To start the second lamp, bring the carbons to-
gether to close the circuits ; close the lamp switch
and open the short-circuiting switch. This puts the
two lamps in series, the current from the first lamp
flowing through the second lamp. The arc at the
second lamp is adjusted in the regular manner while
both lamps are burning. When ready to change
over from one lamp to the other, bring the carbons
of the first lamp together and close its short-circuit-
ing switch, continuing the projection on the second
lamp.
It has been found in practice that the following
scheme gives the most satisfactory results. A minute
or two before the end of a reel of film is reached
bring the carbons of the second lamp together, close
its line switch and open its short-circuiting switch.
The current for the first lamp flowing through the
carbons of the second lamp causes the tips of the
carbons of the second lamp to heat up to a white
heat without actually drawing an arc. Since the
tips of the carbons are heated up by this method a
MOTION PICTURE PROJECTION 345
normal arc is easily and quickly secured when it is
time to change over to the second lamp.
Care must be taken that the two lamps are not
both burning any longer than is necessary, as the
Compensarc is not intended to carry both lamps
continuously. The ammeter on the panel will show
the current flowing through the arc when either one
Fig. 5
A. C. to D. C. Compensarc
or both lamps are burning. The voltage is auto-
matically increased by the machine to compensate
for the increased drop due to the second lamp and
the current is held practically constant.
It is important that all parts of the machine be
kept clean. Oil should not be allowed to collect
either on the machine or on the floor about it, and
the machine should as far as possible be kept free
*46 MOTION' PICTURE PROJECTION
from dust. When the coils of a machine are allowed
to become dirty and oil-soaked, it reduces their in-
sulation strength and eventually causes them to burn
out. A small hand bellows will be found convenient
for removing the dust from the armature windings.
BEAiLS
The oil-wells should occasionally be cleaned and
new oil supplied. They should be filled through the
side filling hole, and not through the top of the
bearing, for if filled through the top the oil is likely
to flow out through the ends of the bearings into the
windings. Only good grades of oil free from dust and
sediment should be used for poor oil or oil containing
sediment wfll greatly shorten the life of the bear-
ings. Immediately after starting see that the oil
rings revolve freely and carry the oil to the top of
the shaft. Keep the oil at the proper level in the
well, that is, nearly to the lip of the overflow gauge.
As soon as the bearing linings become so worn that
the rotor is in danger of rubbing against the stator,
a new set of linings should be inserted. To remove
the bearings, take out- the set screws in the bearing
housings, lift the oil rings and drive out the bearings
with a wooden block of the same diameter as the
bearings. The bearings are a light driving fit in the
housing and must be handled carefully. When re-
pair bearings are supplied for the alternating cur-
rent motors the set screw depression is already in the
bearing, but the direct current bearings, which regu-
late the end play, are supplied without being pre-
viously spotted. They must be spotted before being
put in place, using a 3-16 inch drill and spot-
MOTION" PICTURE PROJECTION
drilling for the tip of the set screw the same dis-
tance from the end of the bearing as is the bearing
being replaced.
COMMUTATOR AND BEUSHES
It is very important that the brashes make perfect
contact with the commutator, and to secure good
contact it is important that both brashes and corn-
Fig. 6
Special Cabinet Panel with Ammeter and Fldd Rheostat
mutator be kept clean and free from carbon dost
and dirt.
To secure proper commutation and proper opera-
tion, the brushes must occupy the correct position
on the commutator. This proper position of the
brush yoke has been determined at the factory while
the machine was on test, and is indicated by corre-
sponding chisel marks on brush yoke and frame.
It is Terr important that these marks indicated by
348
MOTION PICTURE PROJECTION
white lead should be in line to secure satisfactory
operation of the machine.
If the brush holders should become loosened or
moved in any way, they must be carefully reset so
that they make the proper angle with the commuta-
tor as shown in Fig. 7. They must also be so
spaced around the commutator that the distance
from tip to tip of the brushes are exactly the same.
Care should be taken that the brush-holders are
securely fastened at an even height 1-16 inch above
the commutator.
When replacing worn down brushes the new ones
should be fitted to the commutator by means of fine
sandpaper, carefully pulled under, the brush in the
direction of rotation, being held tightly to the con-
tour of the commutator. If the brushes are inspected
once a week and all gum cleaned away from the
brushes so that they move freely in the brush-holders,
Commutator
Direction of
Rotat/on
Fig. 7
Showing Correct Method of Setting the Brushes
MOTION PICTURE PROJECTION 349
much longer life of brushes and commutator will
result. If the pressure is too heavy the wear of
both brushes and commutator will be excessive, while
if the pressure is too light the contact will not be
properly made between brushes and commutator and
sparking may result; the proper pressure of the
springs on the brushes is just sufficient to insure
good contact between brushes and commutator. A
dirty commutator can be best cleaned by rubbing with
a clean cloth saturated with kerosene or machine oil.
To keep the commutator in good condition, wipe it
from time to time with a piece of canvas lightly
coated with sperm or machine oil. Lubricant of any
kind should be used sparingly.
If the commutator begins to cause trouble at any
time, due to roughness, it should be given immediate
attention. Any delay will aggravate the case and
may result in undue sparking, heating and consequent
troubles. The roughness may be removed by polish-
ing the commutator with a piece of very fine sand-
paper by pressing it against the surface of the com-
mutator with a block of wood shaped to the curva-
ture of the commutator face. In using the sandpaper
(emery cloth should never be used) it should be moved
back and forth along the surface parallel to the shaft
to prevent grooving the face of the commutator.
When sanding is finished, the commutator surface
and brush faces must be wiped carefully to remove
any copper dust and grit which may have adhered
to them. If the commutator has been allowed to
become very rough it may be necessary to grind
it down to a true surface, using a small piece of
fine sandstone. In using this it should be steadied
350 MOTION PICTURE PROJECTION
against the brush holders (properly protected) or
other steady-rest. Brushes should be lifted from the
commutator while grinding it. After grinding polish
with fine sandpaper.
If the above treatment does not remedy the trouble
it will be necessary to tighten the commutator seg-
ments and turn down the commutator. The com-
mutator should be trued by taking off the lightest
cut possible, using a sharp tool and high cutting
speed. Following the operation of turning down the
commutator, the mica between the bars should be
carefully cut down below the surface of the bars.
Next remove the tool marks from the surface of the
commutator with very fine sandpaper, and blow all
the copper dust and chips from in and around the
commutator bars, making a final inspection to see
that at no place does the copper dust or chips bridge
over the mica from one bar to another. The truing
of the commutator should be required only after a
long period of service, if the machine has been prop-
erly cared for, and should be done only by someone
familiar with such work.
MOTION PICTURE PROJECTION 351
D. C. TO D. C. MOTOR-GENERATOR SET
For Projection Arc Control
For 2 Arcs in Series Used Alternately
GENERAL
The D. C. to D. C. motor-generator set consists
of two machines, a generator and a motor, coupled
together and mounted on a common base.
The sets are shipped completely assembled and
require only proper installation, filling of the bear-
ings with oil and proper connection to the supply
and lamp circuits before putting in service. Under-
stand that these sets are special machines for use
only on picture projection arcs and cannot be used
for ordinary constant voltage purposes.
The complete equipment consists of the D. C. to
D. C. motor-generator set, proper starting box, two
short-circuiting switches (one for each picture ma-
chine) and the panel on which is mounted the am-
meter and field control rheostat.
INSTALLATION
Install the D. C. to D. C. motor-generator in a
clean, dry, well ventilated location and, if possible,
near to the lamps which it is to operate. Oftentimes
a small room adjoining the projection room is pro-
vided for the set, but in some cases where such ar-
rangement cannot be made the machine is installed
in the basement of the theatre. Avoid inaccessible
locations, as such locations will result in the ma-
chines being neglected, allowed to become dirty and
perhaps damaged.
352 MOTION PICTURE PROJECTION
It is not necessary to provide foundations for
these machines, but the floor on which they are placed
must be firm and free from vibration.
Fig. 2
D. C. to D. C. Motor-Generator Set
The machines are shipped clamped to a pair of
wooden skids which form a foundation for the box-
ing. If possible, leave the machine attached to these
skids until it has been conveyed to the location which
it is to finally occupy. It is preferable that all wir-
ing should be done before the boxing is removed
from the machine, as the boxing will be effective in
keeping the machine clean.
As soon as the machine is unboxed, inspect the
name plate to see that the volts marked on the name
plate of the motor agree with those of the circuit
on which the machine is to be used. The marking of
the generator name plate indicates the volts and am-
MOTION PICTURE PROJECTION
353
peres which the generator is designed to deliver and
this rating should agree with that specified in the
order.
CONNECTIONS
Wiring Diagrams
Diagram Fig. 8 shows the external connections
for the 35-ampere two-lamp series outfit and Fig. 9
shows the external connections for the 50, 70 and
100-ampere two-lamp series outfit.
D. C. TO D. C. MOTOR-GENERATOR SETS
V/ewFrom Bock of Board
Dtrect Current
L/ne
To Uoper Carbon)
Lamp Shor
Circuiting
Switches
Fig. 8
Connection Diagram for 35-Ampfere Lamp Outfit
354
MOTION PICTURE PROJECTION
Wiring
Be sure that the wiring is of sufficient size so that
tKe line drop from the machine to the lamp will not
exceed one volt, or two per cent of the voltage when
the machine is delivering full load current to the
lamp. If too small a wire is used the lamp will be
robbed of some of its voltage and give poor light.
D. C. TO D. C. MOTOR-GENERATOR SETS
Direct Current
Line
To UpperCarboi
Lamp
Fig. 9
Connection Diagram for the 50, 70 and 100-Ampere Lamp Outfit
MOTION PICTURE PROJECTION
355
Fuses
The lamp side of these machines does not require
fuses, as the generators are so constructed that they
will protect themselves against overload current when
the arcs are short circuited.
The motor side of the various machines should be
fused as follows :
Tw 0>
35- ampere
Lamps
Alternately
Two^
50-ampere
Lamps
Alternately
Two^
TO-ampere
Lamps
Alternately
Two
100-ampere
Lamps
Alternately
115 volts
230 volts
550 volts
Fuses
60- ampere
30-ampere
15-ampere
Fuses
80-ampere
40-ampere
20-ampere
Fuses
120- ampere
60-ampere
30-ampere
Fuses
160-ampere
80-ampere
40-ampere
INITIAL STARTING
Before starting the set see that it is perfectly
clean, and that the brushes move freely in their
holders and make good contact with the commutator.
Be sure that the oil wells are clean and filled.
These machines have overflow gauges with hinged
caps. Fill the oil wells through the overflow gauges
rather than through the hinged covers in the bear-
ings. This method will prevent waste and annoy-
ance from overfilling of the oil reservoirs.
Pour in enough oil to show in these gauges. The
thin oil furnished for the moving picture machines,
sewing machine oil, and similar light oils are not
heavy enough; it is better to purchase a can of
"light dynamo oil" and keep it for the motor-gen-
erator.
See that the armature turns freely in the bear-
ings, and that the machine is level.
356 MOTION PICTURE PROJECTION
Make sure that all connections are tight and
agree with the diagram of connections for the outfit
supplied, so that when starting up the armature will
start to rotate in the direction marked on the coup-
ling.
Immediately after starting, see that the oil rings
revolve freely and carry the oil up to the shaft.
Always keep the oil at the proper level in the well,
that is, nearly to the lip of the overflow gauge.
OPERATION
Starting the Motor-Generator
In starting up the D. C. to D. C. set have the
switches at the lamps open. Close the main line
switch and move the lever of the starting box to the
first contact point holding it there for two or three
seconds to allow the armature to start to rotate.
Then move the lever slowly over the remaining con-
tact points until it reaches the running position
where it will be held in place by the retaining mag-
net. If the voltage fails the retaining magnet will
release the latch allowing the starting arm to auto-
matically return to the "off" position stopping the
motor.
To stop the machine open the main switch. The
arm of the starting box should then automatically
return to the "off" position. If it does not, throw
it over to the "off" position by hand.
Starting First Lamp
When the speed of the machines is up to normal
and the arm of the starting box is in running posi-
tion and the rheostat handle set as marked by the
MOTION PICTURE PROJECTION 357
white arrow, short circuit the one lamp by means
of its short-circuiting switch. Then close the lamp
switch of the other lamp and bring the carbons to-
gether so that they barely touch; then separate
them about 1/16 of an inch, gradually increasing
the separation as carbons heat up until proper
length of arc is reached. The D. C. arc should be
from 5/16 to % of an inch long, or about twice as
long as an A. C. arc. Adjust the generator field
rheostat until the proper amount of current is flow-
ing.
If carbons are held together too long, the machine
voltage will be automatically reduced to zero, so
that the arc will not have sufficient voltage and
will, therefore, break when carbons are separated.
Should this occur, keep carbons apart about 10
seconds until machine voltage can automatically
build up again ; then strike the arc as directed above.
The switchboard panel has an ammeter mounted
on it along with the field rheostat and is very useful
as the proper current can at all times be accurately
maintained. As the machine warms up, the handle
of the rheostat may have to be moved one or two
buttons from the mark to maintain the desired volt-
age and current.
If the circuits are all connected as shown in the
diagram the polarity should be as indicated. The
upper carbon must be positive. Should the upper
carbon be negative and the instrument on the panel
read backward, the trouble must be corrected. See
that all connections are made as indicated on the
diagram.
The polarity must come correct if the connections
358 MOTION PICTURE PROJECTION
are made in accordance with the diagram of con-
nections and the armature of the set rotates in the
direction marked on the coupling.
Starting the Second Lamp
To start the second lamp bring the carbons to-
gether to close the circuit, close the lamp switch
and open the short-circuiting switch. This puts
the two lamps in series, the current from the first
lamp flowing through the second lamp. The arc at
the second lamp is adjusted in the regular manner
while both lamps are burning.
When ready to change over from one lamp to the
other bring the carbons of the first lamp together
and close its short-circuiting switch, continuing the
projection on the second lamp.
It has been found in practice that the following
scheme gives the most satisfactory results. A minute
or two before the end of a reel of film is reached
bring the carbons of the second lamp together, close
its line switch and open its short-circuiting switch.
The current for the first lamp flowing through the
carbons of the second lamp causes the tips of the
carbons of the second lamp tc heat up to a white
heat at the tips without actually drawing an arc.
Since the tips of the carbons are heated up by this
scheme a normal arc is easily and quickly secured
when it is time to change over to this second lamp.
Take care that the two lamps are not both burn-
ing any longer than is necessary, as the motor-
generator is not intended to carry both lamps con-
tinuously. The ammeter on the panel will show the
current flowing through the arc when either one or
MOTION PICTURE PROJECTION 359
both lamps are burning ; the voltage is automatically
increased by the machine to compensate for the in-
creased drop due to the second lamp and the cur-
rent is held practically constant.
360
MOTION PICTURE PROJECTION
THE TRANSVERTER
The Transverter is a vertical machine, self-con-
tained and occupies a floor space of less than two
feet square. The panel carrying the switches and
meters can be located at any point convenient to
the operator, while the machine is best placed near
a wall anywhere on a floor not subject to vibration,
and in a location which is not damp and which af-
fords ready inspection.
A pair of steel lugs will be found on the sides of
the generator frame. After the machine is taken out
MOTION PICTURE PROJECTION 361
of the crate, it can be very conveniently handled by
these lugs, should it be necessary to lift it any dis-
tance to its permanent location. When located, it
should be placed upon the four pieces of cork com-
position which are sent with the machine, and which
serve to minimize vibration and at the same time in-
sulate the frame from ground. It is not necessarv
to bolt it down.
Installation Instructions
Wiring Make connection from the A. C. line ser-
vice to the starting switch and from the starting
switch to motor terminals, 1, 2 and 3; then close the
switch and make sure that the armature rotates in
the direction indicated by the arrow on the top bear-
ing housing. If the armature rotates in the wrong
direction, it must be reversed by interchanging any
two of the A. C. motor terminals.
Caution Do not change connections inside of
Transverter unit to correct direction of rotation or
polarity. The machines are all checked up complete
with their equipment when tested. The motor must
be connected to proper side of the line and connec-
tions to panels must be made correctly to bring po-
larity of the instruments and lamp carbons correct.
Fuses Fuse the A. C. motor side of these ma-
chines only. The D. C. Generator circuit does not
require fuses or switches other than shown on the
wiring print. The A. C. fuses at the A. C. motor
starting switch must be of large enough capacity to
carry the maximum load of the machine.
Wiring to Lamps Use wire of sufficient size to
carry rated current of Transverter to connect from
362 MOTION PICTURE PROJECTION
L and A on the Transverter to panelboard and
lamps. No. 14 or No. 12 size wire may also be used
to connect F on Transverter to the F on the Field
Regulator in panel board.
The Transverter is a motor generator with the
motor below and the generator above, the two being
built into one unit.
The shaft of the generator is supported at its
upper end in a radical ball bearing, its lower end
taking half of a coupling, the other half of which is
located at the top of the motor shaft. The shaft
of the motor is supported by two radical ball bear-
ings, top and bottom, and a ball thrust, which takes
the combined weight of both rotor and armature.
The coupling is so constructed as to carry a cen-
trifugal fan which provides ventilation from above
and below, discharging the air out of openings in
the side of the unit.
Grease cups are provided for each of the bearings,
the latter being enclosed in dust-proof housings.
The driving unit is a simple, two or three phase
induction motor of ample capacity, running very
close to constant speed regardless of load.
The generator is of the constant current type.
The design is bipolar, which lends itself most readily
to constant current characteristics as shown in the
curve.
The field winding is shunt with interpole windings
for commutation. The brushes and interpoles are so
positioned relative to the main poles as to get a prac-
tically constant current over a wide range of voltage,
which, in the double arc machine, reaches from 50 to
approximately 115 volts. The position of the
MOTION PICTURE PROJECTION 363
Parts Making Up the Transverter
brushes on the commutator should never be shifted
by rocking them, as this will change the entire char-
acterization of the machine. If any sparking de-
364
MOTION PICTURE PROJECTION
WIR1/46 DIAeRA/^
of-
ARC
CorKTMt
velops, it is due rather to imperfect brush contact
than brush position.
Operating Instructions
Have lamp carbons separated and lamp switches
open.
Close motor starting switch.
Close that switch which controls lamp that you do
not wish to use.
Permit the generator voltage to build up before
attempting to strike the arc, then strike the car-
bons together quickly and lightly, separating them
immediately to about 1-16 of an inch, gradually in-
creasing the separation as the carbons heat up until
a proper length of arc is reached. ( Note : 55 volts
MOTION PICTURE PROJECTION 365
will then show on the Voltmeter, provided proper size
carbons are used and they are set at correct angle.)
Adjust for amperes desired by means of the Field
Regulator in panel. (Note: The Regulator pro-
vides means of obtaining more amperage from the
Transverter than its rated capacity. This greater
amperage should not be used continuously. It is in-
tended only in order to provide for very dense films
or colored pictures. Regulator also provides means
of obtaining less amperage than the rated capacity
of the machine, thus providing for films that do not
require so much light. If the operator will take ad-
vantage of the provisions that have been made for
obtaining the high and low amperage, he will im-
prove the projection and at the same time effect a
considerable saving in the projection light bills.)
For Obtaining Two Arcs Simultaneously Assum-
ing that one arc is alreay in operation :
Adjust that arc to about a 55 volt length;
. Bring the carbons of the second arc lamp to-
gether and while in that position open the switch
controlling that lamp, then slowly separate the car-
bons to about 1-16 of an inch, gradually increasing
the separation as the carbons heat up until this
second lamp also has a 55 volt arc length. (Note:
The Voltmeter on the panel board will then be in-
dicating combined voltage of the two arcs.)
To discontinue the use of either arc, merely close
switch controlling that lamp.
Note: If operator will follow the above instruc-
tions carefully, he can heat up the carbons in the
second lamp or burn in a new trim of carbons with-
out disturbing the arc of the other lamp. The two
MOTION PICTURE PROJECTION
arcs can be used simultaneously for dissolving the
pictures.
Phanton View of Transverter
General Care
Keep the machine clean.
Keep the commutator clean (but do not use sand
or emery paper on it). If it becomes dirtyi hold a
pad of coarse canvas or cheese cloth against its sur-
face while running, and when free of dirt wipe the
MOTION PICTURE PROJECTION 367
surface with a clean cloth pad that is slightly moist-
ened with pure vaseline.
Do not permit the carbon brushes to become too
short, as disastrous sparking will result. A new set
of carbon brushes should be put in before the old
ones are completely worn out. When putting in new
brushes it is well to first put in two, one in each hold-
er at opposite ends of the commutator, then as soon
as they are worn into a perfect fit to the surface of
the commutator, replace the remaining old brushes
with new ones.
The machine has ball bearings and they require a
very small amount of lubrication.
The three grease cups on the machine should each
be given one turn twice each week. If this is done
these grease cups will require refilling once each
thirty to forty days.
Note: Refill the grease cups with Transverter
grease only, as other kinds of grease will be likely to
injure the highly polished steel balls and surfaces
of the bearings.
Troubles and Remedies
If the brushes are not replaced as explained above,
the commutator may become blackened and require
attention either by the application of a stone, or, in
severe cases, it may require the removal of the ar-
mature so as to turn the commutator in a lathe.
Should the bearings become dry or an improper
lubricant be used, it may cause the destruction of a
bearing and require its replacement.
In case it is necessary to have any repair parts or
supplies, order these direct from the factory, giving
the serial number on the name plate of the machine.
368
MOTION PICTURE PROJECTION
Connections of a Double-Arc Transverter, with Emergency
Inductor System
MOTION PICTURE PROJECTION
t-MOTO* HINCMTOK fUHCi. FOR 3 AH C LAMPS
Wiring Diagram For Two Motor Generators and Control
Switchboard, Two Projectors and One Spotlight, Permitting
Single or Dual Operation of Motor Generators. J. E. Robin.
370
MOTION PICTURE PROJECTION
Se. 1 hat beo>iwge a.re
filled wtU 9cd. heavy M/
Scc^Kat pKa.se x/n-es a
cenn*c)eL to rn roT.r:
in clacKwo'<(iret-ic/
Sv4/itcUs*iA2.If olo.
ftp A Ofc"'
dawn t\ >9h
Sii>9 It oj3
into l/f KanA tk
IK v^kieh fs>fia^
U.)ii/*r/4 C f, /re
Vasolme applied, sparingly
, . 1 ubriccnt to re^VC*
htKe insilt ocrtt/n
W Hr fWWlH' h mv1
^ K~
^3
Jgg
O Pl| tf
g Q 8
0-8
S3
tt <
-C316
Connection for Westinghouse Motor Generator 427
Connection for Type A. R. Motor 426
Connection for a Double Arc Transverter with
Emergency System 868
Connection of Motor End of A. C. to D. C, Compensarc . . 339
540 MOTION PICTURE PROJECTION
"A Better
Summer Business"
This is what we call a book-
let we have issued. It will
prove mighty interesting to any
exhibitor. It shows him how
easily he can make his house
pay big profits in hot weather.
If you want to increase your
business during the summer,
you need this booklet.
We'll gladly send you a copy
free.
Just drop us a postcard.
And if you are building
a new theatre, asfy m also
for our Circular C-1 .
Monsoon Cooling System, Inc.
ROOM 201 70 W. 45th ST., NEW YORK
MOTION PICTURE PROJECTION 641
Construction of A. C. Transformer 509
Control Switches for Motor Generator 424
Controlling Resistance Device 53
Conversion Tables 457
Convex Lenses 126
Cooling and Heating *of Theatres 167
Coulomb 10-28
Current 24
Curent Frequency 10-38
Current Required by Motors 454
Cycle of Operation in a Four-Cycle Gas Engine 412
D
D. C. to D. C. Generator 352
D. C. to D. C. Motor Generator Sets 351
Device for Controlling Resistance 63
Diagram of Connection for A. C. Compensarcs 70
Diagram of Elementary Transformer 58
Diagram of Generator 410
Diffuse Lighting Screens ; . 244
Direct Current 10
Discharging and Recharging Batteries 391
Distance to Which Full Load May be Carried 464
Double Arc Transverter Wiring Diagram 864
Dynamos 7 .... 332
E
Economizer Connection 64
Economizer, Hallberg 61
Effect of Rheostats in Series and Multiple 505
Electric Arc 232
Electric Time System 143
Electric Time System, Connections for 148
Electrical Apparatus for Studios and Theatres 414
Electrical Energy in Mechanical Units 30
Electrical Resistance 41
Electrical Terms 7
Electricity 11-23
Electro-Motive-Force 24
Electrolyte 397
Elementary Projection Machine 114
Elementary Rheostat 42
Elementary Transformer 58
542
MOTION PICTURE PROJECTION
"Acme" Model 14 A Semi-portable
MOVING PICTURE PROJECTOR WITH
STEREOPTICON ATTACHMENT
Here is the universal machine a semi-portable Moving
Picture Projector superior to any other similar machine
ever made, and with Stereopticon Attachment that makes
an unbeatable combination. You can run moving pic-
tures alone, or lantern slides alone. But its greatest
feature is its instant adaptability from one to the other.
The only machine with which you can show SLIDES
while changing reels. Think of the advantage of being
able to show a few slides (as next week's announcements,
or advertising slides) and thereby hold the attention of
your audience while you are changing reels. The weight
is only 50 pounds. The dimensions are 19% inches high,
8% inches deep and 21^ inches wide.
Send for Catalog of this and other "Acme" Models
ACME M. P. PROJECTOR CO., 1134 W. Austin An, Chicago
MOTION PICTURE PROJECTION 543
Energy ' 29
Emergency Service M. P. Generator 429
Equivalent Focus 11-124
Equivalent of Units of Lengths 463
Equivalent of Electrical Energy in Mechanical Units 80
Even Tension Reel 251
Examination Questions 527
Excessive Speed of Motor 211
Extra Lamp for Mazda Work 277
F
Failure of Motor to Start 202
Few Facts Concerning the Simplex 260
Film 234
Film Speed 20
Fire Trap 11
Flashing of Motor 214
Flexibility of Carbon Arc. 228
Flexible Armored Cable 71
Floor Plan, Single Floor Theatre 112
Focusing Mirror, Mazda Equipment 275
Fort Wayne A. C. to D. C. Compensarc 334
Foundation for Motor Generator 421
Freezing Point of Electrolyte 396
Fuses 83
Fusing of Motor Generator 855
G
General Care of Transverter 365
General Points on Generator 439
General Storage Battery Data 396
Generation of Electricity 33
Generator, Motor 334
Generator Troubles, Causes and Remedies _ 371
Geneva Intermittent Movement 263
Grounds, Testing for 85
Gundlach Lenses . 127
H
Hallberg 4-in-l Mazda Transformer 66
Hallberg Economizer 61
544 MOTION PICTURE PROJECTION
BETTER LIGHT BETTER DEFINITION
With the
"KEENOLITE"
Three Combination Lense
FOR A BRIGHT, STEADY ARC
"General Electric Generators"
Can't Be Beat, We Carry a
Stock For Immediate Delivery
INDEPENDENT LIGHTING PLANTS FOR
MOVIE THEATRES
"IMSCO"
Engine and Generating Sets
These Are But a Few of the IMSCO
Products. We Also Carry a Full
Line of Movie Supplies
Independent Movie Supply Co., Inc.
W. H. RABELL, President
729 SEVENTH AVE., NEW YORK, N. Y.
CATALOGUE ON REQUEST
MOTION PICTURE PROJECTION 545
Head of Powers 6 A 202
Heart of the Simplex 262
Heating and Ventilating of Theatres 167
Hertner Transverter 364
Horse Power 12
Horse Power to Watts 457
How to Locate Break in Armature 371
How to Measure Copper Wire 448
I
Ideal Projection Room 96
Impedance 37
Imsco 32- Volt Generating Plant 379
Inches to Millimeters 459
Incorrect Speed of Motor 211
Induction 12-58
Inductor, Power's 60
Installation of D. C. to D. C. Motor Generator 351
Installing Westinghouse Generator 423
Instructions for Installing Compensarc G7
Instructions for Installing Peerless Arc Controllers 181
Instructions for Installing the Simplex Projector 255
Instructions for Operating the Acme Projector 154
Instructions for Setting Up Simplex Mazda Equipment. 273
Intermittent Gear Ratio 20
Intermittent Movement . 192
Intermittent Movement with Oil-Tight Casing 199
International Cinema Center Projection Room 100
International Ohm 25
Joule, The 29
Keen-o-lite Lens 141
Keystone Effect 499
Kilowatt 18
548 MOTION PICTURE PROJECTION
The
Automatic Arc Control
For use on all makes of Projectors
A Complete Automatic carbon feeding device that has
established a new high standard of excellence in screen
illumination impossible to obtain with the hand-fed arc.
Will completely free the operator from the feed handle
of the projector. Always maintains the same volume of
light on the screen.
Write for circular
THE J. E. McAULEY MFG.
30-34 N. Jefferson St. Chicago, 111.
MOTION PICTURE PROJECTION 549
N
National Carbon Combinations.. 221
O
Objective 14-125
Ohm 31
Ohm's Law 81
Oiling System 432
Oiling the Projector 164
Operating the Transverter 364
Operation of Speed Control I 26T
Optical Projection 121
Overheating of Armature 374
Overheating of Generator Bearings 376
Overheating of Motor Starter 212
P
Parts Making Up the Transverter 363
Parts on Head of Simplex 295
Pedestal, Simplex 319
Peerless Arc Controller 178
Penal Laws New York 477
Phantom View of Transverter 865
Picture Aperture 20
Plan of Projection Room, Capitol Theatre 95
Plan of Single Machine Booth 93
Plug Fuses 88
Points to Remember 450
Points to Remember About Transformers 61
Portable Projectors 152
Position of Screen 248
Power 29
Power Required for Driving Fans 458
Power's 6B Cameragraph 191
Power's Intermittent Movement 192
Power's 6B Take-up 206
Power's Inductor 60-62
Power's Loop Setter 203
Power's Rheostat 45
Power's Type "E" Lamphouse and Lamp ] . 185
550 MOTION PICTURE PROJECTION
A Permanent Feature
For Your Theatre
No theatre is complete in its
equipment without an up-to-date
Cooling and Ventilating System.
No up-to-date theatre is com-
plete without the Typhoon
Cooling and Ventilating System.
More than a thousand theatres
are already equipped with the
permanent feature.
TYPHOONS
TYPHOON FAN COMPANY
345 W. 39th ST. :-: NEW YORK
1044 Camp Street 800 South Olive Street
New Orleans Los Angeles, Calif.
64 West Randolph Street
Chicago, 111.
MOTION PICTURE PROJECTION 551
Precaution Against Fire 523
Pressure, Electric 23
Principles of Optical Projection 120
Projection Angle 20
Projection Arc 219
Projection Distance 15
Projection Layout Ill
Projection Lens 132
Projection Lens Foci 20
Projection Lens Table 138
Projection Objectives 21
Projection Room 89
Projection Room International Cinema Center 100
Projector Carbon Manufacturing Process 221
Q
Quantity, Energy and Power 28
Questions and Answers 494
R
Rate of Battery Discharge 392
Reactance 41
Rear View of Acme 163
Recapitulation 466
Rectifiers 73
Reel 21
Reflecting Power of Walls, etc 461
Reflection 15-122
Refraction 15-123
Regulating Engine to Procure Proper Amperage 394
Regulations Governing the Transportation of Inflammable
Film , 493
Reo Theatre Booth Plan 92
Repairing Break in Armature 371
Resistance 25-41
Resitance Box 41
Resistance, Calculation of 27
Resistance Affected by Heating 27
Resistance Inversely Proportional to Cross-Section 26
Resistance Proportional to Length 26
552 MOTION PICTURE PROJECTION
For New and Used
PROJECTION MACHINES
PORTABLE PROJECTOR
MOTOR GENERATORS
THEATRE SEATS
ELECTRICAL EQUIPMENT
BOOTHS, SCREENS
ETC. ETC.
THEATRE SUPPLY Co.
124 WEST 45th STREET
NEW YORK
Established 1910 BRYANT 9375
MOTION PICTURE PROJECTION 553
Restoring Weakened Cells 401
Reversing Motor Generator 433
Rewinder, Simplex 321
Rewinding Table 91
Rheostats 41
Rheostats in Multiple 48
Rheostats in Series 46
Right and Wrong Way to Set D. C. Arc 218
Robin Cinema Time System 143
Robin Multiple Unit Rheostats 50
Robin Signal Telegraph System 229
Rotary Converter 370
Rules Governing the Granting of Operator's License 467
S
Screens 239
Section of Carbon Holders 189
Series Connection Rheostats 46
Setting for National Carbons 225
Setting Mazda Lamp in Holder 274
Setting Up Simplex Projector. ' 255
Self Induction 612
Short-Circuit 16
Showing Effect of Arc Burning Upside Down 229
Showing Correct Method of Setting Brushes 348
Shutter, Light 16
Signal Telegraph System 229
Simplex Adjustments 264
Simplex Arc Lamp 327
Simplex-Boylan Even Tension Reel 251
Simplex Mazda Equipment 259
Simplex Parts, Head 295
Simplex Parts, Lamphouse 305
Simplex Speed Regulator 315
Simplex Take-up 247-307
Simplex Type "B" 266
Simplex Type "S" Projector 254
Sixty-Cycle A. C. Current 89
Size'of Wires for Motors 456
Spark Plug 408
Sparking Distances in Air 458
Sparking of Motor 202
Specific Gravity, Test of 398
Specific Resistance 27
554 MOTION PICTURE PROJECTION
S. M. P. E.
To Keep Abreast of the Times
Read the Instructive Technical Articles
in
The Transactions
of the
Society of Motion Picture
Engineers
Issued Twice a Year
Can Be Obtained From
L. E. BRAGDON or WILL C. SMITH
Motion Picture News 90 GOLD STREET
729 7th AVENUE NEW YORK CITY
MOTION PICTURE PROJECTION 555
Speed Indicator Attached to Powers 146
Speed Indicator Attached to Simplex 144
Speed Regulator 317
Speer Carbons 230
Spherical Aberration 123
Spread Lighting Screens 244
Standard Rheostat Dimensions 52
Standard Rheostat Shelf 94
Starting a Motor Generator 430
Starting an Imsco Engine 384
Starting the Compensarc 341-355
Starting the Second Lamp of Compensarc 344
Step-Down Transformer 57
Stereopticon 17
Storage Battery, Preparing for Service 379
Striking the Arc 221
Sulphating . 403
Switchboards ..102-104-106
T
Table of Brightness per Candlepower 453
Table of Electrical Units 460
Table of Resistivities and Conductivities 453
Take-up 207
Take-up Pull 21
Take-up Powers 206
Take-up Simplex 247
Technical Description of Intermittent Movement 194
Test of Specific Gravity 398
Test Lamp 19
Testing for Grounds 85
Testing Lamphouse for Grounds 87
Testing Rheostats for Grounds 87
Theory of the Engine 404
Thirty-two- Volt Generating Plant 379
Threading the Simplex 271
Three Combination Lens 141
Three hase 18
Three Phase 18
Three Unit Motor Generator 416
MOTION PICTURE PROJECTION
Howells Cine Equipment Co.
LET US KNOW
YOUR WANTS
Everything
From
The
WE CAN FILL
THEM
JOSEPH C. HORNSTEIN
General Manager
Phone
BRYANT 7206
729 Seventh Avenue, New York City
MOTION PICTURE PROJECTION 557
Three Wire System 76
To Set Light Shutter 452
To Start a Motor 431
Transformer 57
Transformer Connections 59
Transverter 360
1 ransverter, Troubles and Remedies 367
Troubles and Remedies of Transverter 367
Two 150-Kil. Generators, 50-Cycle Induction Motors 416
Two Arcs to a Three-Wire System 49
Two Light Generator 435
Two Phase 18
Two Phase Compensarc Connection 341
Type "E" Lamp 190
Type S. K. D. C. Motor 427
Type S. K. Generator 428
U
Useful Equivalents for Electric Heating 465
Units of Length 463
Units of Electrical Measurement . 25
V
Variable Speed Control 267
Ventilating and Heating of Theatres 167
View of Capitol Theatre Projection Room ' 96-98
View of Pin Cross 200
View of Switchboard for Imsco Engine 881
Voltmeter 19
Voltmeter Connections 75
Volts Lost on Copper Wire 455
W
Watt .- , . ; 30
Watts Consumed per Hour for Given Candle Power 462
Watts to Horsepower 457
Westinghouse Generator 421
Westinghouse Generator for M. P. Projector 415
Westinghouse Motor Generator, General Information.. 421
Wire Table 449
558 MOTION PICTURE PROJECTION
HAFT ONE"
THE SCREEN OF A THOUSAND
ANGLES
IT HAS NO "FADE-OUT"
Shows Uniform Distribution of Light over
its Entire Surface Regardless of Angles
Produces Brilliant Pictures Without Glare
or Eye Strain and Shadows that are Rich
in Detail. Its "Half-Tones" are Remarkable
Folding and Rough Handling Cause no
Injury
It is Absolutely Opaque and May be
Washed
If You are Interested in High-Grade Pro-
jection Write for Sample
RAVEN SCREEN COMPANY
257 SOUTH SECOND AVENUE
MOUNT VERNON, N. Y.
MOTION PICTURE PROJECTION
559
Wiring for Mercury Arc Rectifier 73
Wiring for Peerless Arc Control 182
Wiring Diagram for Westinghouse Generator 425
" Two Lamp Equipment 282
" Single Lamp Equipment 284
" 35 Ampere Outfit 858
" 50 Ampere Outfit 854
" Arc Controller 182
" Double Arc Transverter 364
Wiring for Rotary Converter 370
Wiring for Single Lamp on A. C 278
Wiring for Single Lamp on D. C 280
Wiring for Two Generator Control Switchboard 369
Wiring Instructions for Transverter 861
Working Distance 19
Working Operations of Loop Setter 208
Working Principle of Elementary Projection Machine... 113
560 MOTION PICTURE PROJECTION
INDEX TO ADVERTISERS
Acme Portable Machine Co 542
B. F. Porter 562
Haftone Screen 558
HowelPs Cine Equipment 556
Independent Movie Supply Co 544
Inter-Ocean Film Corp 176, 177
J. E. Robin 562
James R. Cameron 546
Monsoon Cooling System 540
Motion Picture News in
Nicholas Power Co 538
Peerless Arc Control 548
Screen Magazine 561
Simplex Machine Co < !#
Society of Motion Picture Engineers 554
Speer Carbon Co 231
Theatre Supply Co 536, 552
Typhoon Fan Co 550
/or Business
^W.
561
$10,000.00 REWARD
Will be paid to any person who can prove that
B. F. PORTER
did not sell and install the Simplex Projectors
in the
CAPITOL THEATRE
Broadway at 51st St. New York City
Read the Capitol Program
B. F. PORTER
Exclusive Equipment
729 SEVENTH AVE. :-: NEW YORK CITY
Consult an Engineer of Reputation
To plan the Projection System, Electrical Work
and Booth Layout before building or making
alterations. Save hundreds to thousands of dol-
lars. Avoid constant costly Reconstruction.
References any architect or Broadway theatre
of importance
"Robin Cinema Electric Speed Indicator." The
original and only accurate device to run a per-
->^re on schedule and to allow perfect syn-
ci**~. ~* * l * ""'sic with the picture.
Special Rheostats, Switchboards, j.viiui.V-- '^**"
Control Panels
Stock Devices of Merit Only
"Highest award Panama-Pacific Int'l Exposition"
J. E. ROBIN
729 SEVENTH AVE. :: NEW YORK CITY
562
The Finest Theatres in
the Principal Cities Use
SIMPLEX
"The Cheapest in the Long Ruh"
JP*^*^ ^^^^it
w
UNIVERSITY OF CALIFORNIA LIBRARY
Mazda Simplex Projector
MADE AND GUARANTEED BY
317 East 34th St~ NewTforic
563