CHAPTER XV

THE MOTION PICTURES AS AN AID TO SCIENTIFIC INVESTIGATION

Rapid strides are being made in the utilisation of animated photography as an aid to scientific investigation. It is a development useful in all fields of research where phenomena can be recorded in pictorial form. Dr. E. J. Marey, the eminent French scientist, was the pioneer in this work. One has only to peruse his classic work "Movement"[4] to realise the comprehensive nature of his studies. So thoroughly did he cover the ground of chronophotography, as it was then called, that it is difficult to conceive where any new application of the motion picture can now be made.

[4] "Movement," by E. J. Marey. Heinemann, 7_s._ 6_d._

The Aurora Borealis always has been a subject fascinating to scientists. Numerous papers and brochures have been written about it, and many elaborate drawings have been prepared to convey some idea of its characteristics and its kaleidoscopic changes. The drawings, however, fail to convince, and even the few still-life photographs which have been taken are uneventful.

Realising this deficiency a Danish professor is striving to record the Aurora Borealis in motion upon the celluloid film. A special camera has been designed for his work, and with this it is intended to snap the phenomena from a convenient northern point such as Spitzbergen or Greenland, not only for the benefit of the scientific world but also for the general public which entertains only a hazy conception of the "Northern Lights." It need hardly be said that if this investigator should succeed in his difficult quest he will reveal upon the screen one of the most extraordinary wonders of the world. While the marvellous and weird colouring effects will be missing, the curtains of light that drape the sky, and the strange luminous shafts and glares which light the heavens, should provide a film of intense interest and fascination.

The moving-picture camera is also being applied to the recording of solar eclipses with a view to obtaining a more impressionistic and intimate idea of the activity and extent of the flames which shoot from the surface of the sun. Wonderful still-life pictures of these effects have been taken, and it is only fair to assume that they should be capable of being caught by the motion-picture camera. Efforts are also being made to secure photographs of the heavens, but the difficulties are very great. The long exposure required in this case is a heavy drawback, but seeing that the slowest movements of Nature can be recorded by the cinematograph, and may be speeded up in projection to convey the effect of animation, there is no reason why similar moving pictures of other worlds should not be obtained by combining the moving-picture camera with the telescope. The moon followed through its phases would yield an interesting study, and, incidentally, a film of this character would possess considerable educational value.

At the present moment great activity is being manifested in the application of the cinematograph to mechanics. Two Sheffield investigators have designed a steel-testing machine to which is attached a microscope and a cinematograph camera. The piece of steel to be tested is placed in the machine and the cinematograph is set in motion. By throwing the resulting pictures upon the screen it is possible to follow exactly what takes place in the molecular construction of the steel while it is under test.

The idea has been applied to many other phases of mechanics with equal success, and there have been many discoveries of a technical nature which have had their effect upon manufacturing processes.

Another series of technical experiments was carried out by Dr. Otto Füchs, professor of engineering at the German Technical High School of Brünn. The purpose was to elucidate some hitherto obscure points in connection with the working of steam hammers. Investigations in this field have hitherto proceeded on the graphic principle, the results being recorded by a stylo continually travelling over calibrated paper. It is admitted that this system leaves much to be desired because the stylo is not sufficiently sensitive, and fails to record many of the smaller and more important movements. Accordingly, Dr. Füchs conceived the idea of using the moving-picture camera in the anticipation that much missing data might thus be discovered.

A special apparatus was designed. In reality it is an ingenious combination of the moving-picture camera and the graphic method. There is a paper tape that passes continuously over two rollers and has two stylos constantly bearing on it. These stylos are connected with two indicators attached to the sides of the cylinder of the steam hammer, and they supply a continuous record of the steam pressure. The paper tape is moved by an electrically-driven gear, while time intervals are indicated by means of clockwork mechanism. So much for the graphic portion.

What the cinematographic portion supplies is a continuous animated record of the movement of the ram of the hammer. Attached to the ram is an index which moves up and down over a scale divided into centimetres. Both the index and the scale are illuminated so that the result given by the camera shows a series of photographic images of the oscillating motion. Above the illuminated finger and scale is a clock similar to Marey's chronoscope and Gilbreth's timepiece, driven by clockwork, and in synchrony with the remainder of the mechanism. This scale likewise has its points of division illuminated. Its use is to supply the time factor without which such experiments are useless.

The ram, the index-finger, the scale and the clock are all recorded upon the film, so that it is possible to tell the varying speeds at which the ram moves throughout its travel. The photographing speed may be varied as desired, and as a different position is caught in each picture, the distance the ram travels between two successive exposures, together with the time occupied in completing the cycle of movement, may be accurately gauged. The combination of the paper tape recorder with the photographic part of the apparatus affords a complete record of the ram's performance.

The results are naturally of a severely technical character and of interest only to persons concerned with mechanics. But to these they are very important indeed. The experiments which have been completed by Dr. Füchs have thrown much light upon a difficult engineering problem. They have served to answer questions affecting the design of the hammer and its most economical efficient operation which would otherwise have been insoluble. From the public point of view the films possess no interest whatever, inasmuch as the subject is illuminated and photographed in such a way that only the features of technical interest are brought out strongly upon the film.

Another interesting and profitable province of the cinematograph is that concerning ballistics. This has been worked out by Monsieur Lucien Bull at the Marey Institute with his camera capable of taking two thousand pictures per second under the illumination of the electric spark. While this investigator did not apply his invention directly to ballistics he indicated the manner in which such work could be carried out. The success of his experiments, however, prompted another investigator to enter the field. This was Dr. Cranz, of the Berlin Military Academy. The apparatus this professor evolved has been devoted exclusively to the study of the flight of projectiles and to photographing the action of the mechanism of the magazine type of firearm.

The Cranz apparatus is somewhat more complicated than that designed by Monsieur Bull, though the fundamental principle of operation is the same. The film, resembling an endless belt, is passed round two steel cylinders, one of which is driven by an electric motor. Images of standard size are produced under the illumination of the electric spark, which concentrates the maximum amount of light upon the moving object. The photograph is in silhouette, and the disposition of the apparatus is such that five hundred consecutive pictures can be made in one-tenth of a second, the period of exposure varying between one-millionth and one-ten-millionth of a second. The outstanding feature of the installation is the special and novel type of interrupter. It consists of a pendulum by which the sparking is started before the projectile is fired and made to continue until the film has been exhausted.

Some of the results obtained by this apparatus are very remarkable. When the films are projected upon the screen at the average speed of sixteen pictures per second the flight of the bullet can be followed with ease. One film shows the effect of a bullet striking a suspended india-rubber ball filled with water, and brings out the remarkable formations the ball assumes during the infinitesimal part of a second when the bullet is passing through it. Another interesting film shows the effect of a high velocity bullet striking a bone, and the manner in which the bone is splintered and smashed by the force of the impact conveys a realistic impression of the destructive force of the modern rifle projectile. The deadliness of the automatic pistol is well known. Since seven shots may be discharged in four seconds, the movements of the mechanism are too rapid to be followed by the naked eye. Yet by means of the Cranz apparatus every motion is caught, and the whole is slowed down in projection to such a degree that the complete cycle of the firing of the shot and the expulsion of the cartridge, which normally occupies only a fraction of a second to complete, occupies about thirty seconds upon the screen. When these pictures were exhibited for the first time a number of black specks were observed to accompany the expulsion of the spent cartridge. These proved to be grains of powder which had not been ignited. Their existence had never before been suspected, and the result was curious. After minute examination of the pictures a change was effected in manufacture of the cartridge so that the waste of powder through non-ignition should be reduced to the minimum. The success achieved in this direction was shown by the absence of non-ignited grains in subsequent pictures.

Another wonderful series of moving pictures was prepared by an American ophthalmic surgeon. He embarked upon elaborate researches to gain further information about the eye and its peculiarities both in sickness and in health. The illumination of the eye was carried out very cleverly, so as to obtain the greatest possible brilliancy without causing fatigue to the subject. Accordingly his pictures were absolutely normal. In these experiments glass plates were used, for the reason that they give results much finer and more detailed than celluloid. In celluloid the grain of the base of the film is apt to be disturbing to very fine studies. In this way a great deal of new information was gained. One of the most remarkable discoveries was that the sensitiveness of the organ of sight is far greater than was previously supposed, and that the eye never is absolutely still, even when commonly regarded as being fixed and steady.

During the past two or three years the uses of the cinematograph in medicine have been much extended. A former chapter has described its application to the study of microbic life, but the latest innovation is to employ it in the operating room. The pages of the medical papers are filled with reports of curious and unusual surgical operations, but mere reports are necessarily somewhat imperfect. In view of these circumstances it occurred to one eminent surgeon that a cinematographic record would form a first-class supplement to the technical description. The initial experiment proved a complete success, and accordingly the practice has been extended. In this direction France, Germany, and the United States are taking a very active part. Films of this character can be made to serve two useful purposes. They are valuable for the transmission of practical information between medical men and are useful in the lecture room among the students. Suppose a hospital in New York has a strange and unusual case for operation. Only the students in that establishment have the opportunity of witnessing it. But by the aid of the moving-picture camera and a lecture it can be reproduced in photographic animation upon the screen for the benefit of medical graduates in the various hospitals throughout the world.

In research work, such as the study of new and unusual diseases, especially those of a tropical nature, it is possible to obtain a continuous record of a subject from the moment of infection through the various stages of the malady. For instance, in the study of sleeping sickness in Uganda, Colonel Bruce had formerly to content himself with a graphic record or chart of the fluctuations of a patient's condition, with explanatory notes introduced here and there when a sudden change in the temperature or general behaviour of the patient developed. With the cinematograph it is possible to obtain a pictorial record which conveys a more forceful and exact impression of the symptoms. An interesting indication of what could be done in this direction was the film prepared by Dr. Comandon. He used a monkey for his subject, infecting it with the microbe of sleeping sickness discovered by Colonel Bruce. The effects which the bacteria produced upon the monkey were admirably illustrated, together with the changes that various remedies wrought in its condition.

So far as concerns the application of the cinematograph to scientific research the greatest strides have been made in physiology. This was due to Marey's enthusiasm in this branch of science, and the establishment of the Physiological Institute in Paris where such investigations were carried out upon a most exhaustive scale. The results of Marey's investigations are given in several volumes and in hundreds of papers which he sent to the various French scientific societies. There is no reason why the contributions of the cinematograph to physiological knowledge should not be equalled in other branches of science. Up to the present the investigation of scientific phenomena with the aid of motion-pictures has not been carried far, but there are many signs that its sphere will be extended in the future.