THE MOTION-PICTURE MACHINE
MACHINES THAT MAKE SIXTEEN TINY PICTURES PER SECOND AND SHOW
THEM AT THE SAME RATE MAGNIFIED SEVERAL THOUSAND TIMES--MOTION
PICTURES IN SCHOOL--OUR BOY FRIEND SEES THE WHOLE PROCESS OF
MAKING A MOTION-PICTURE PLAY.
"I have just been to the moving-picture show," said the young man
whose inquiring turn of mind has brought him into touch with so many
recent inventions. His friend in the laboratory had just finished a
very successful chemical experiment and seemed glad to see the boy.
"Did the pictures move very much?" he asked with a smile.
"Of course they did. They moved all the time."
"No, they only seemed to move, for as a matter of fact there are no
such things as 'moving pictures.' We call them 'motion pictures' now,
for that comes nearer to expressing the idea.
"Cinematography, which is the technical name for the whole art of
motion pictures, is based on one of nature's defects, whereas most
inventions are based on some of nature's perfect processes. The
defect is called by the scientists the persistence of vision, which
means that after you look at an object, and it is quickly taken from
before your eyes, the image remains there for the fraction of a
second.
[Illustration: ELECTRICITY ENOUGH TO KILL AN ARMY PERFECTLY
HARNESSED
The Oscillator shown on the left sending an alternating current
from the earth into a large reservoir and back at the rate of
100,000 oscillations per second causes the tremendous electrical
explosions as the reservoir is filled each time. The flames in
this experiment were 22 feet long.]
[Illustration:
Courtesy of Thomas A. Edison Inc.
A BATTLE SCENE IN THE STUDIO
In this picture the stage director can be seen shouting
directions to both actors and photographer at once.]
"With this in mind you will see how the cinematograph is simply
still photography worked out so as to show a series of snapshots at
such speed that the eye cannot notice the change from one picture to
another, but will see only the changing positions of the figures.
Each picture shows the figures in a little different position, in the
same order that they move, so that the whole series thrown on the
screen at high speed shows the figures moving just as they do in real
life."
"But where does visual persistence come in?" asked the youth.
"It would be plain if you could see the pictures thrown on the screen
twenty times as slowly as they are, for each snapshot of each stage
of motion must be displayed separately. It must remain perfectly
still for an instant and then must be moved away while the shutter
of the projecting machine is closed. When the shutter is opened
again the next picture is thrown on the screen. Now, through the
persistence of vision, the image of the first picture remains in your
brain, photographed on the retina of your eye, while the shutter is
closed, and you are not conscious that there is nothing on the white
screen before your eyes.
"The scientific explanation of this is simple enough: After an image
has been recorded by your eye it will remain in the brain for an
instant even after the object has been removed. Then it fades slowly
away and gives place to the next image sent along the optic nerve
from the eye. Thus the eye acts as a sort of dissolving lantern for
the motion-picture man, and lets one image fade into another without
showing any perceptible change in pictures. Thus the 'moving picture'
is only a scientifically worked out _illusion_ of motion."
The scientist went on to say that with marvellously constructed
machines this scientific fact has been turned to such account that
boys and girls in some of the schools now study geography partly from
motion pictures, and some of the most wonderful sights of nature
are seen every day by millions of people as they sit comfortably in
their seats in the motion-picture theatre. A few years ago, before
the invention of cinematography, the magic lantern was largely used,
as many boys will remember; but it could only show scenes in which
there was no movement--or in other words, scenes that were confined
to still-life photography. Nowadays every boy is familiar with
motion pictures depicting great historical occurrences, parades,
inaugurations, coronations, volcanoes in eruption, earthquakes,
buildings burning and crumbling, railroad wrecks, shipwrecks, scenes
in every country in the world and plays of every imaginable kind.
The motion-picture photographer takes pictures in the frozen North,
and in the densest tropical jungles. He goes close to the craters of
volcanoes in eruption to make a film of the terrifying flow of molten
lava, and he sails the seas in the worst storms, that boys and girls
who have never seen the ocean may understand its mighty upheavals.
One motion-picture outfit was taken to the Arctic regions off the
coast of Alaska where the volcanic activity in Behring Sea frequently
causes new islands to spring from the ocean, or old ones to sink out
of sight, in an effort to record on the motion-picture film the birth
of a new island or the death of an old one.
"Ever connected with scientific research, cinematography," said the
boy's friend, "is now one of the important branches of recording the
phenomena of nature through which great scientific discoveries are
made. Of late years we have heard much about germs, and the science
of germs called bacteriology. A great deal has been learned about
this most important factor in the preservation of our health, through
the study of disease germs, by watching their activities through the
medium of the cinematograph. The little parasites are photographed
under a very high power microscope and the film is cast upon a screen
in the usual way.
"Also exploring parties and parties that go into remote places to
search for additions to our store of scientific knowledge invariably
carry motion-picture outfits. One of the most notable examples of
this was the expedition of Lieut. Robert F. Scott in his search for
the South Pole. Lieutenant Scott carried many hundreds of feet of
standard film, a good camera, and a portable developing outfit, with
which he made pictures of the Antarctic Continent, in order to show
the world the things that he and his men risked their lives to see.
"As I said before, the cinematograph is rapidly growing as an
educational force, and Thomas A. Edison, the pioneer inventor and
the leader in the development of the cinematograph, declares that it
will in a short time completely do away with books in the study of
geography. It is already in use in several special school and college
courses, and with the improvements in the non-inflammable film, which
will be explained later, it can be taken up far more extensively."
The man went on to say that in this connection Mr. Edison, who had
been watching the schoolwork of his own twelve-year-old son Theodore,
recently said in the magazine _The World To-day_ (now _Hearst's
Magazine_):
"I have one of the best moving-picture photographers in the world in
Africa. I told him to land at Cape Town, and to take everything in
sight between there and the mouth of the Nile. His pictures will
show children what Kaffirs are and how they live. He will show them
at work, at play, and in their homes. They will be life-size Kaffirs
that will run and skip or work right before the children's eyes.
But the Kaffirs will be but the smallest part of what the African
pictures will show. The biggest beasts of the jungle--the elephants,
lions, rhinos, and giraffes--will be shown, not in cages, but in
their native haunts. The city of Cape Town will be shown with its
characteristic streets and its shipping. The broad veldts over which
Kruger's armies marched will be shown just as they are, with here
and there a burgher's cottage. Every step in the process of mining
gold and diamonds will be put upon the film. The Nile will be shown,
not as a small black line upon a map, but as a body of beautiful
blue water, alternately plunging over cataracts and creeping through
meadows to the sea. Then will come the Pyramids, with natives and
tourists climbing them, and, lastly, the great cities of Alexandria
and Cairo. Would any child stay at home if he knew such a treat as
this was in store for him at school? Would he ever be likely to
forget what he had learned about Africa?"
"Of course," continued the man in the laboratory, "this is but an
example of the use of motion pictures in schools. Many of you boys
have probably seen them in special lectures on other subjects, for
they can be used to show how people live and work in every part of
the world and how the various commercial products that so largely
govern our lives are made."
But the motion-picture man, he explained, is not at all dependent
upon what really happens for his films, because if he cannot train
the eye of his camera on some occurrence that he desires to transfer
to a film, he reproduces it in a studio, spending thousands and
thousands of dollars, if necessary for actors, scenery and stage
fittings. Nothing is too difficult for the motion-picture man, and
he has never proposed a feat so daring but what he could find plenty
of actors willing to take the necessary parts. Battles, scenes from
history, sessions of Congress, railroad wrecks, earthquakes and
hundreds of other spectacles have been planned, staged and acted out
by the makers of cinematograph films, while, of course, all the plays
that we see on the screen are planned and carefully rehearsed before
they are photographed.
This all means that cinematography has become a gigantic industry,
giving employment to hundreds of actors, photographers, and the army
of men and women engaged in making and showing the films, to say
nothing of the thousands of picture theatres that have sprung up in
every city and town in the country.
While the boy's friend was telling him these things about the
adventurous life of the motion-picture man, the listener sat
spellbound.
"I'd love to see some motion pictures made," he said. "The machines
must be wonderful."
"Well," answered the scientist, "we can do that, and if you'd like we
can go up to one of the motion-picture studios some day soon and see
the whole process from beginning to end."
He was as good as his word, and several days later they were
initiated into all the tricks of cinematography at one of the biggest
laboratories in the country. We will follow them there and see what
they found out about the machines by which motion pictures are made
and shown.
With the fact clear in mind that cinematography is simply a series
of snapshots of figures in motion, taken at high speed and thrown
on a screen at a similar rate so that the human eye is tricked into
sending to the brain an impression of moving figures rather than
a series of still photographs, the various machines necessary in
cinematography will not be difficult to understand.
Before there can be a cinematograph play there must be a negative
film upon which the pictures are taken, a camera to take the
pictures, an apparatus for developing them, a positive film which
corresponds to the printing paper in still photography, upon which
the pictures are printed from the negative film, a printing machine
to print the positives from the negatives, and lastly a projecting
machine to throw the picture upon the screen in the schoolroom,
college lecture room, or theatre.
Every boy who is an amateur photographer is familiar with the
photographic film. Up to the time the method for making practical
cinematograph films was discovered in this country, scientists
vainly tried to portray motion by the use of photographic plates, but
had little success. In a very short time after Eastman had announced
the discovery of a celluloid substance that was transparent, strong
and flexible, light, and compressible into a small space, Edison
announced a machine for showing motion pictures.
The film base, or, in other words, the material which takes the
place of the glass used in glass plates, was discovered by George
Eastman in 1889, after years of painstaking experiment with dangerous
chemicals. The base is a kind of guncotton called by chemists
pyroxylin, which is mixed in wood alcohol. The guncotton is made by
treating flax or cotton waste with sulphuric and nitric acids. After
the guncotton and the wood alcohol have been thoroughly stirred up,
the mixture looks like a thick syrup, but it is about as dangerous a
syrup as ever was brewed, for its ingredients are those of the most
powerful explosives. Its technical name is cellulose-nitrate. It is
poured out on a polished surface, dried, rolled, trimmed, and after
being coated with the sensitive material that makes it valuable for
photography, is ready for delivery to the motion-picture maker in
lengths up to 400 feet.
[Illustration: THE MEN WHO GAVE THE WORLD MOTION PICTURES
Eadweard Muybridge, called the "Father of Motion Pictures."
Thomas A. Edison, inventor of the motion-picture machine.]
[Illustration: THE MOTION-PICTURE PROJECTOR
This is the standard Edison projector from two points of view,
showing its complicated mechanism as clearly as possible.]
One of the interesting points to remember about these films is that
although they are made in lengths up to 400 feet they are all one and
three eighths of an inch wide, and the three eighths of an inch
is given over to a margin at each side of the picture. That leaves a
width for each picture on the film of just one inch. The height of
each picture is three quarters of an inch. Fancy a photograph one
inch by three quarters of an inch! No matter how clear it is you
could not see with the naked eye all its details, and so it is in the
cinematograph picture. It is so clear and sharp that when put under
a good magnifying glass details that cannot be seen by the human eye
are noticed. Now fancy multiplying the area of each little picture
2,700 times, and think of the chance for magnifying imperfections!
And yet that is the amount that each picture is magnified in throwing
it on a screen of the average size.
The films are coated with the sensitive emulsion in two degrees. The
negative films must be as sensitive as possible to light, as they
are intended to receive the shortest possible exposure, while the
positive films, or the ones which correspond to the print paper in
still photography, are made less sensitive to light, inasmuch as they
are exposed for a longer time in the printing machine.
Fireproof films are probably one of the most important developments
in the whole great motion-picture industry, for through these,
schools, colleges, churches, lecture halls, and other public places
not fitted with the fireproof box in which the motion-picture
operator works, can have the advantage of cinematography.
It was a difficult matter to find a non-inflammable film, for
science has not yet discovered a base that can be made without
cellulose, but the base we know to-day was treated so as to be
non-explosive and practically non-inflammable. This film base is
called cellulose-acetate, and when it is exposed to an excessive
heat, as, for instance, the beam of the motion-picture lamp when the
film is not moving, or when it touches a flame, it melts but does not
blaze up. In the melting it gives off a heavy smoke, but there is no
serious danger from this, as there is from the spurting flames from
an exploding cellulose-nitrate base.
The films are packed in metal airtight and lightproof boxes and sent
to the motion-picture firms, where they begin a complicated and an
interesting career. The first stage is the perforating machine,
through which all films, whether negative or positive, must go. The
holes are made along the two edges of the celluloid strips, just as
shown in the picture opposite page 176. There are sixty-four holes to
the foot, on each side of the film, and each hole is oblong-shaped,
as can be seen, with a width of about one eighth of an inch and
a depth of about one sixteenth of an inch. This is known as the
Edison Standard Gauge, and it is observed by practically all the
motion-picture firms in the world.
The perforations along the edges of the films furnish the means for
drawing them through the camera, printing machine, and projector; and
as the correct movement of the films is one of the important factors
in making good pictures, they must be absolutely mathematically
exact. A fault in perforation of even as much as one thousandth
part of an inch is apt to cause the film to buckle in the camera or
projector and ruin the whole thing.
There are several different perforating machines in use now, and
all of them are claimed by their makers to be perfect. It will not
be necessary for us to take one of these machines to pieces further
than to see that the holes along the edges of the films are punched
by hardened steel punches. The films unwind from one bobbin, pass
through the perforating device, and wind upon another bobbin. Of
course the work must be done in absolute darkness, except for a small
ruby lamp, as the films are so sensitive to light that any rays other
than faint red would spoil them.
After perforation the negatives and positives are ready for use. The
negative goes to the photographer in its light-tight metal box to
be run off in making a film of a historical scene, a comedy, some
wonderful phenomenon of science, or any one of a million different
subjects. Just for the sake of seeing everything in its proper order
we will assume that the negative is about to be used in portraying a
comedy about the troubles of a book agent, and that it is all done
in the studio where the scientist and his boy friend watched this
very film made.
Now for a look into a motion-picture camera--something few people
get, because the competition among the various cinematographers is
keen, and those who hold patents on cameras fear infringement.
The camera, which is enclosed in a strong mahogany box, stands upon
a tripod. It is about eighteen inches long, eighteen inches high,
and four inches wide. (This size varies with the make, and kind of
work required.) The left side opens on a hinge, while on the right
side are the ground glass finder, the distance gauge, and a dial
to register the number of feet of film used. In the rear of the
camera is a small hole which connects with a tube running straight
through the box so that the operator looking through can sight it
like a telescope, before the film is exposed. When the sighting and
focusing are completed the opening is closed with a light-tight cap,
and the film can be threaded through the camera. Having no bellows
for focusing like an ordinary camera, the lens of the motion-picture
camera is moved back and forward a short distance in the little tube
in which it is set, to aid in the focusing. Of course the lenses of
these wonderful snapshot machines are the best that money can buy and
the factories can turn out.
[Illustration: A SECTION OF MOTION-PICTURE FILM
This is the exact size of the little pictures we see on the
screen almost life size. Note how slowly the changes appear. It
takes only one second to take sixteen of these.]
[Illustration:
Courtesy of Thomas A. Edison, Inc.
MAKING A MOTION-PICTURE PLAY IN THE STUDIO
Note the photographer, the stage manager beside him, and the
battery of arc lights making the scene in the studio as light as
day.]
In the rear half of the camera are two boxes. The top one holds the
unexposed roll of negative, while the exposed film is rolled in
the bottom one. Roughly speaking, the film unwinds from the top
spool, passes out of the containing box through a slit, over a set of
sprockets into the "film gate," down past the lens and shutter, where
it is exposed over a lower set of sprockets, and through a slit into
the lower containing box, where it is wound on a spool.
[Illustration: A MOTION-PICTURE CAMERA
A--Box for coil of unexposed film.
A´--Box for coil of exposed film.
B--Film passing over rollers.
B´--Exposed film passing over rollers.
C--Cogwheel which draws out film.
D--Teeth which jerk film past lens.
E--Lens and film-gate.
H--Cogwheel which draws in exposed film.]
"It looks simple enough, doesn't it?" asked the photographer,
who was explaining the making of a moving-picture play to his
visitors. "Well, it is a simple idea, but it takes a very
complicated and a wonderfully accurate machine to accomplish the
desired result.
"In the first place our cinematography is just still photography
at high speed. We have to take approximately sixteen snapshots a
second, so you can see that it takes a perfect machine to move
the film along fast enough so that we can get sixteen good,
clear, sharp pictures only slightly bigger than a postage stamp,
on our film between the ticks of your watch.
"Now if you look through the little hole at the back of the
camera you will see that the scene in front of us is in the
proper focus, and if you look at the little ground glass finder
at the side here you will see it just the same way, except that
it will be upside down. Now I will close the telescope focus at
the rear so that when the film is brought down before the lens it
will not be light struck."
The "threading" of the camera then began. "This little flap
sticking out of this slit in the top box," continued the
cinematographer, "is the end of the film, which is tightly wound
up in its holder. You notice that I draw it out and thread
it between these rollers, making sure that the teeth of the
sprockets enter the perforations along the sides of the film. I
also make sure that the sensitized side of the film is turned
out, so that the light coming through the lens will strike it
first. After the negative has been led over the sprockets you
notice that it is allowed to make a loop of a couple of inches of
slack. Then it is led into the important device we call the 'film
gate.'
"You see the gate is hinged and that these little claws or
fingers running in grooves take hold of the perforations. The
next thing is to close the hinged gate so that the film is
tightly held against the aperture, through which the light
strikes it and makes the picture. Below the gate we let the
negative make another loop and then thread it over another system
of rollers and sprockets and so to the slit in the lower box,
where the exposed negative is rolled.
"The camera is now loaded and threaded and when I give the crank
by which the wheels are turned a few trial turns you can see the
way the mechanism works. In the first place you must understand
that the film has to be jerked down with an intermittent motion.
Don't forget to look for the intermittent motion, because, after
the persistence of vision, that jump and stop, jump and stop, is
the most important thing in cinematography--intermittent motion!
"You can see as the crank turns that the sprockets pull the film
out and guide it along its course, and the little fingers jerk it
down the space of one picture, or three quarters of an inch, at
each jump. When the fingers are jerking the negative down, the
shutter must be closed, and when the fingers are making their
back trip to take a new hold on another length of film the strip
must be as still as the Washington Monument, for the shutter to
open, let in the light and transfer the image before the lens to
the negative."
The photographer turned his crank and all the wheels in the
camera began to move. The sprockets working in the perforations
pulled out the film and made the loop larger. The little fingers
entered the perforations and jerked the film down, taking up some
of the slack of the loop. The reason that the loop is formed is
to prevent the film being torn by a hard jerk by the fingers when
it is taut.
"Now if your eye were quick enough--which it is not"--said the
photographer, "and you could see behind the gate, you would see a
movement like the following repeated sixteen times to the second:
Crank turns, top sprocket adds three quarters of an inch to the
top loop, bottom sprocket takes up three quarters of an inch of
bottom slack loop, fingers spring from groove and carry film
down three quarters of an inch, inconceivably short pause while
shutter opens and picture is taken; during this pause, while
film is stationary, fingers jump back into groove, slide back
to starting point without touching film and shutter closes. The
shutter is a revolving disk between the lens and film, and the
holes in the disk passing the negative admit the light."
After a roll of negative film has been exposed it is sent to the
studio dark room for development. Every precaution is taken, of
course, that no ray of light other than that which comes from
the ruby lamp shall enter this room where films representing
hundreds, and perhaps thousands, of dollars are being developed.
The actual process for developing is no different from that used
in developing other films, but the difficulties in handling a
delicate snakelike, strip some 300 or 400 feet long and 1-3/8
inches wide are tremendous. All amateur photographers appreciate
the difficulties of developing in one string a roll of twelve
films of a reasonable size, but think of handling a roll of film
several hundred feet long no wider than a ribbon, and holding
sixteen pictures to each foot of surface!
The difficulties of scratching, tangling, etc., were overcome
by systematizing the process. In some cinematograph dark rooms
the films are wound on racks about four by five feet, and then
plunged into the various baths, which are in vertical tanks of
convenient size. In yet other dark rooms the films are wound upon
drums about four feet in diameter and revolved in horizontal
tanks, only the lower part being immersed. The only difference is
that the racks can be manipulated easier than the drums.
While in the motion-picture dark room the boy visitor asked
the photographer in charge whether an amateur could step in
and develop a few hundred feet of film granted that he had the
necessary materials.
"Of course he could," came a cheerful voice from the darkness.
"It's just the same as developing a roll of ordinary films,
only we do more in a bunch than the amateur. If you'll step
over here and watch this reel that we are now putting into
the developing bath you'll see that it does just the same as
the single film developed in the amateur's dark room." After
watching this trained photographer and his assistant for a
few minutes, however, the newcomer decided that it was not an
amateur's job, but rather one of the most delicate operations in
all cinematography, for the developer can remedy many faults of
exposure by bringing out an under-exposed film or toning down an
over-exposed one.
Leaving the dark room the next stage of the negative is the
drying room, where the film still on the rack is hung up to dry.
This drying is a very difficult process because there is great
danger of the film either becoming too brittle and cracking or
of its being not hard enough. The air in the drying room has to
be kept at a certain even temperature and it must be filtered so
that no dust or impurity can injure the film.
After it has been properly dried the film again is wound upon a
metal spool, put in an airtight box and sent to the assembling
room, where the various scenes that go to make up the picture
play, taken at different times and on different rolls of
negative, are joined together in their proper order to make a
complete play in a single roll about one thousand feet long.
After the negative film is developed, dried and wound upon a
metal spool it is sent to the printing room, where positive
prints are made from the original impression. Right here it may
be well to say that on a negative film or plate in any kind of
photography white appears black and black appears white--hence
the name negative. The paper or film upon which the print is to
be made turns black wherever the light strikes it, so that when
the negative is laid over the positive and exposed to a strong
light the rays quickly penetrate the white spots on the negative
and turn the corresponding spots on the positive black. The light
does not penetrate the places on the negative which are black,
and consequently leaves those places on the positive white. The
result is that the positive shows the image just as it appears to
the eye.
The principle of printing positive films, then, is the same as
the principle of making photographic prints or positives from
ordinary still photography plates or films, but of course it is
far more complicated because of the mechanical difficulties of
bringing the two long, unwieldy strips of film together in the
proper position. The whole process is carried out by a machine
which takes the place of the printing frame into which the
amateur so easily puts the still-life photographic plate and
printing paper.
There are several motion-picture printing machines in use in this
country, but in their central idea they are similar, as they
all pass the negative and positive films before a very bright
light so that the impressions on the negative are transferred to
the positive. The invention of this machine was a necessity for
the commercial success of motion pictures, for obviously it was
impossible to lay a strip of film several hundred feet long and
about an inch wide in a printing frame over a positive film of
the same length and width.
[Illustration: A MOTION-PICTURE PRINTING MACHINE
A-A´--Rollers for negative film.
B-B´--Rollers for positive film.
C--Film gate where positive is held over negative for printing.
D-D´--Negative film.
E--Unexposed positive film.
E´--Exposed, or printed positive film.
F--Light which, shining through film gate, imprints image of
negative on positive.]
The explanation of one printing machine will suffice to indicate the
general principle. Some of the machines are worked by hand power, but
in the larger reproduction studios electric power is used practically
altogether for running the battery of printing machines.
The spool of negative film is slipped on to a spindle so that it can
unwind easily, and immediately underneath it the roll of unexposed
positive film, properly perforated along the edges in exactly the
same way that the negative film is perforated, is suspended on a
similar spindle. Of course the only light in the printing room is
the photographer's ruby lamp.
The two films unwind and pass downward, with the sensitive surfaces
to the inside, and the positive on the outside of the negative.
They are drawn together, and with the positive stretched flatly
over the negative they pass over a pair of smooth rollers and
toothed sprockets which enter the perforations of the two films with
mathematical accuracy. They then make a small loop and enter a side
hinged gate which holds them tightly against the printing aperture.
This aperture is a hole just the size and shape of each picture on
the film, and through it shines a very bright light which casts its
direct rays upon the negative and imprints the image of the negative
film upon the sensitized surface of the positive film. After passing
the printing aperture, the two films make another small loop, run
down to another toothed sprocket wheel and roller, and then separate,
the printed positive being rolled upon one spool and the negative
upon its spool below.
The action of this machine is very similar to that of the
motion-picture camera, for like the device for taking the
photographs, the movement must be intermittent in order to obtain
good results.
If the operator desires to see whether the two films are in exactly
the right position and everything is going smoothly, he can, by the
use of a lever in the printing gate, drop a little red screen between
the light and the films, and by looking through the hole see through
the unprinted positive, and the developed negative, to the light
inside.
After a roll of positive has been printed, it is developed by just
about the same process as is used in bringing out the images on the
negative film. Then, after it is dried, the various scenes are joined
together, titles and sub-titles put in, any final editing that is
necesary is done, and the positive film is ready to be put on the
projection machine for the first trial.
The preparation of the titles, sub-titles, and other explanatory
writings that are thrown on the screen in the course of a
cinematograph play is a comparatively simple matter. The words are
written or printed out in large letters on cards and photographed
by a camera with a slower movement than the ones used for recording
moving figures. The positives are made from the negatives so taken,
in the same way that positives of other films are made, and after
development and drying are ready to be joined to the film in the
proper places.
Every firm engaged in the fascinating business of making and
reproducing cinematographic plays gives the most careful and
painstaking attention to the first "performance" of a film. Of course
it is held in private before only the officials and a few critics
invited for the exercise of their judgment. The event amounts to the
same thing as the dress rehearsal of a play to be reproduced upon
the stage, and any changes that are necessary in the judgment of the
critics cause just about as much trouble. Any one of a hundred things
may be wrong. Some little incongruous detail in the scenery may be
noticed, some jarring gesture by an actor or a scene in which the
action does not proceed fast enough.
If the officials of the firm decide that a film is below their
standard, parts must be cut out, and new parts photographed over
again until the whole thing suits requirements. Sometimes one scene
must be done over many times before it suits exactly, and several
hundred feet of film wasted. At a cost of about three cents a foot,
it is plain that the waste in film alone is great, but when a big
scene with a hundred or so actors in it has to be done over again,
the cost of assembling the company, paying their salaries and other
expenses is enormous.
Finally, when the officials themselves are satisfied with a
film it is thrown on the screen for the board of censors in the
various cities, and if it measures up to standard, and contains no
objectionable features, it is ready for public reproduction.
When all this is done, the printing machine again comes into play,
and as many prints of the negative as are needed are struck off, for
in cinematography, as in still photography, it is a simple matter
to run off as many prints as are desired, once a good negative is
made. These prints then are sent out to as many theatres, in as many
different cities, as desire them, and released for public view on the
same day in every theatre in the country.
Having looked at the motion-picture camera, and at the complicated
process for developing and printing the films, we are now ready to
climb into the little fireproof box from which comes the beam of
light that throws the pictures on the screen. This is the projector
and it is probably the most complicated of all the machines used in
cinematography. As it was a development through the application of
well-known mechanical principles we will not go into this subject
more deeply than merely to understand its central principle, which is
intermittent motion.
The result toward which the inventors worked was a magic lantern such
as was familiar to every boy ten years ago, that would throw upon the
screen the tiny consecutive pictures on the film, with such speed,
and at the same time so clearly and steadily, that the effect would
be that of figures in motion. Most boys will remember the flickering,
flashing and jumping that used to be noticeable in motion pictures,
and many are probably aware that it was the improvement of the
projecting machine that did away with these objectionable features.
The essential parts of the projecting machine are the lantern with
its light and lens, and the device for running the positive film
before the light with the proper intermittent motion. It might
be said generally that the projecting machine looks like a magic
lantern, but on close examination it will be seen to be an extremely
complicated affair.
The powerful electric light, usually an arc light, which is placed in
a metal box a few inches behind the rest of the projector, directs
its rays through the glass condensers, thence through the film,
and thence through the lens, which throws the image upon the white
screen or curtain. The condensers are made of two carefully ground
glass parts. The first is dish shaped, with the concave side turned
in toward the light and the convex side turned outward. Immediately
against it is another condenser the same diameter and convex on
both sides so that the collected rays from the dished part are shot
forward to a point where they will all converge. This point is the
centre of the lens. From the lens the rays of light are projected in
a widening beam to the white screen on which the pictures appear.
The film is passed before the beam of light at a point between the
condensers and the lens, so that the image is projected through the
lens. The film is run before the light with the figures upside down,
like in the ordinary stereopticon, and the lens turns the image right
side up again.
The most interesting part of the solution of the problem is the
advantage taken of the persistence of vision. Photographed at the
rapid rate of sixteen a second, and thrown upon the screen at the
same rate of sixteen a second, it is plain that the stage of motion
shown in the pictures every sixteenth of a second is reproduced.
With the inability of the eye to tell that the screen is merely
exhibiting separate photographs, the appearance is of motion. In most
persons this visual persistence is only about one twenty-fourth of a
second, but that is long enough to allow animated photography to be a
pleasing illusion to them, for it gives the shutter of the projector
time to hide one picture while the mechanism moves the film down to
the next picture, bring the film to a dead stop, and let the shutter
open again to reveal the next stage of animation.
The manner in which modern mechanical skill took advantage of
this physiological defect, proved many years ago by the leading
scientists, is nearly as interesting as this slight defect in
nature's own camera--the eye.
Above the film gate is a metal fireproof box (many of them are lined
with asbestos) in which is the roll of unprojected positive film.
Below it is another similar box in which the film that has been shown
is wound. The motion, which is directed either by a crank turned by
hand or by electrical power, is the same speed, and practically the
same in detail, as that of the film in the cinematograph camera. From
the film box the film runs to a roller, where a sprocket enters the
all-important perforations and draws out the strip to make a small
loop above the film gate.
The shutter is placed in front of the lens. It is made up of a
black metal circular disk, with either two or three open spaces,
and a similar number of solid or opaque spaces. In general it looks
like a very wide flat aeroplane propeller. Like the movement of the
camera, the film is stationary while the shutter is open, and when
the shutter is closed the film is jerked down three fourths of an
inch, or the length of one picture, and brought to a dead stop by
the time the shutter revolves and is open again. This is repeated
sixteen times every second, so the film is cast upon the screen for
one thirty-second part of a second, and the screen is blank one
thirty-second part of a second while the shutter is closed and, as we
might say, the scenes are being changed for the next act. Although
the movement is just the same as in the camera, it may be well for
the sake of making the thing perfectly clear to go through the motion
very slowly.
For the sake of keeping out of fractions entirely too small for our
consideration we have assumed that in both camera and projecting
machine the shutter is open one thirty-second part of a second and
then closed one thirty-second part of a second, the whole operation
taking one sixteenth of a second. As a matter of fact the effort
of the experts in animated photography is to have the shutter of
the camera open for just as brief a space of time as possible, and
on the other hand it is their effort to have the shutter of the
projecting machine open just as long a space of time as possible, and
closed as short a time as possible. In other words, they desire to
shorten the time when there is nothing on the screen, and lengthen
the time for the eye to photograph each image on the brain. By using
a little different mechanism in the film gate of the projector this
is accomplished to some extent, as well as obtaining a clearer,
steadier picture than formerly was shown.
You will remember that in the camera and printing machine the film
was jerked down by little teeth or fingers.
The simpler of the two methods in general use on projectors now is
called the "dog" movement. It is composed of an eccentric wheel
placed below the film gate, with a little roller projecting from it.
The wheel revolves and once every sixteenth part of a second the
roller is brought around so that it strikes the film and jerks it
down the three fourths of an inch that makes the space of one picture.
[Illustration: A MOTION-PICTURE STUDIO
This is where a great many of the Edison Photoplays are made.
Besides all the other departments there is room on the stage for
several different plays to be photographed at one time.]
[Illustration:
Courtesy of Thomas A. Edison, Inc.
A REALISTIC FILM OF WASHINGTON CROSSING THE DELAWARE
This picture was taken in zero weather on a real stream with real
ice menacing the actors in the boats.]
The other method is known as the "Maltese Cross" movement. The name
is taken from the fact that the chief sprocket wheel is shaped
somewhat like a Maltese Cross. This wheel, with four notches in it,
is attached to the sprocket below the film gate, and it is driven
intermittently by a wheel with a pin that enters one of the notches
on the Maltese Cross wheel at each revolution, and pushes it
around the space of one quarter of a turn. This of course turns the
lower toothed sprocket and jerks the film down the space of one
picture. On the next revolution of the driving wheel the pin enters
the next notch, turns the Maltese Cross wheel another quarter of a
turn, and, by the motion imparted to the sprocket, jerks the film
down another three quarters of an inch, thereby pulling another
picture into place as the shutter opens.
Recent improvements on this movement have largely done away with the
jar resulting from the pin catching the notches in the cross. The
wheel that looks like a Maltese Cross has, instead of four notches,
three grooves, dividing the wheel into three equal parts just as if
a pie were cut into three equal parts but the knife stopped short,
leaving a solid hub in the centre. The space between each groove
represents the length of one picture on the film. Without going into
a long, tiresome, technical explanation of this very important little
feature of the projecting machine, it will suffice to say that the
three-groove wheel is connected with the sprocket underneath the film
gate. Near it is a revolving arm, and upon this arm is a horizontal
bar. When the arm makes a revolution, and reaches a point where it
touches the three-divided wheel, the mechanical adjustment is so
fine that the horizontal bar enters the groove, and the revolution
of the arm carries the three-divided wheel around one third of
a revolution--or the space from one groove to another--turns the
sprocket and pulls the film down the space of one picture, with a
quick steady pull. After getting this far, the arm on its upward
course leaves the three-divided wheel, which stands still while the
shutter is open until the arm gets around again, and as the shutter
closes pulls the sprocket around another space.
The strong light concentrated upon the film, in just the same way
that you concentrate the sun's rays upon your hand with a burning
glass, is very apt to set the film afire, particularly if through
any slip in the machinery it stops in its rapid progress of about a
foot a second. As machinery is not infallible, the manufacturers have
invented various safety devices for protecting the film in case the
machinery stops. Of course this is not necessary when non-inflammable
film is used.