THE KINETOSCOPE STEREOPTICON.
Ever since the kinetoscope was brought to public attention and proved to be so popular, inventors have been striving to perfect apparatus for success-fully projecting these miniature images upon the screen by means of a stereopticon producing the same effect of motion as in the kinetoscope. In the kinetoscope the successive images illuminated by reflected light are seen through a lens, enlarging them considerably, say from an image half an inch in diameter to about four inches. But the problem in the kinetoscope stereopticon was to successfully magnify these little images several thousand times and secure sufficient illumination on the screen to make them appear distinct and clear.
Two factors in solving the problem have been the use of the electric arc lamp as an illuminant and of continuous transparent celluloid flexible films supporting the sensitive film and subsequent pictures, so that during this year several forms of apparatus have been invented, not only in this country but in England and France as well, for producing and projecting such miniature pictures. Most of our readers will recall the zoetrope toy, in which is placed a strip of pictures, the circumference of the cylinder being pierced with small vertical rectangular apertures. As the cylinder is rapidly rotated, the eye, in observing the pictures through the slits, only sees each picture the fraction of a second, and as one picture after another merges into the next, the sense of motion is conveyed to the brain. Carrying out this plan with scientific accuracy is what the kinetoscope and similar machines do.
Various projecting machines have been introduced under such names as the vitascope, the phantascope, cinematographe, kineopticon and bioscope, and have been in use in several of the variety theaters of this city. Our illustrations describe more particularly the vitascope, said to be designed by Mr. Edison, but which is similar in detail and construction to the phantascope invented by Mr. Charles F. Jenkins, who has originated new ideas concerning the details of projection and of the mode of taking the original pictures. Mr. Jenkins has furnished us with a series of photographs made with his camera, shown our upper engraving. The various successive motions of “practicing putting the shot" are shown in these fifteen pictures, and may be traced by beginning at the lower left hand corner and reading upward for each column of pictures.
His device for taking the views is shown in Fig. 5, exterior Fig. 6. On a shaft is fixed a disk supporting four lenses, and geared to the shaft is a smaller shaft arranged vertically, engaging a bevel gear on the axis of the film-winding reel. As the shaft is revolved by the handle outside, the lenses are brought respectively behind the opening in the front of the box and transmit the momentary image, as they pass the opening, to the moving sensitive film going in the same direction as the moving lens and at the same speed, the exposed film at the same time being wound up on the top reel. With the same apparatus the positive pictures on a roll of film may be reeled off from one spool to the other, being projected by the electric light the rear, and illuminated by the rotating condensers, one for each lens, to the eye looking through the lens aperture or upon a small screen, reproducing in sequence the motions as originally taken. By this method the use of slitted rotating disk shutters is avoided; there is greater illumination, more detail in the pictures and they may be made somewhat larger, which greatly assists in their better reproduction on the screen.
The pictures are made at the rate of twenty-five to a second, about three-quarters of an inch in diameter and one-quarter of an inch apart, on a continuous sensitized celluloid strip about one and a half inches wide, having perforations in its edges in which the sprocket wheels of the projecting device engage. Fig. 1 shows the complete projecting apparatus having in the rear a compact Colt electric lamp, in front of that a condenser, next in advance of that the ribbon picture film traveling from the upper to the lower reel, and finally the lens for projecting the illuminated image on the screen. On the rear, between the condenser and film, is observed the electric motor for operating the feed mechanism. Fig. 2 is another view of the stand complete showing the resistance coil used to modify the strength of the current, running lengthwise between the two ends of the stand, switches, etc., for regulating the application of the current. The film, after passing behind the lens, is wound up on the reel below.
In Fig. 3 the use of the apparatus in a theater is shown. It is placed in a cabinet surrounded by curtains in an upper gallery, the images being thrown forward upon a screen erected on the stage. In projecting pictures of this kind it has been usual to employ shutters operating in unison with the movement of the picture ribbon, but after a series of experiments it was found the salve effect of motion could be produced by causing the ribbon itself to have an intermittent movement without the use of shutters at all, which greatly simplified the apparatus. Allowing that twenty-five images pass before the lens per second, it has been ascertained that the picture may remain stationary 11/12 of that interval and another picture substituted in the remaining 1/12 of the interval without destroying the continuity of effect as observed by the eye. The film-working device, based on this idea, will be seen more in detail in Fig. 4. The electric motor operates a main shaft, to which is geared a worm engaging a gear on the shaft of the main sprocket pulley that draws the picture ribbon downward at a uniform speed. Back of this shaft may be seen the main shaft, intended to rotate rapidly, on the end of which is a disk having a roller eccentrically fixed thereto. Just behind this is the standard, supporting spring tension fingers through which the film passes.
The operation is as follows : From the supply reel at the top the picture ribbon passes downward through the spring tension fingers behind the lens, ants, as it is drawn forward by the main sprocket pulley, is quickly pulled downward by each rotation of the rapidly moving eccentric roller on the disk, which movement changes one picture for another. The sprocket pulley meanwhile takes up the slack of the ribbon, so that at the next rotation the eccentric roller quickly pulls the film down and makes the change. From the sprocket pulley the film is carried to the winding reel, operated automatically from the main shaft by means of a, pulley, or, when it is desired to repeat the subject over and over, the endless thin is allowed to drop into folds in a box located under the sprocket pulley, passing out of the rear upward over pulleys, arranged above the tension spring lingers, downward between them again to the main pulley.
Fig. 7 is a diagram of a film-moving mechanism of an English inventor, Mr. Birt Acres, which has been successfully operated in London.
The picture film is taken from an upper reel passed over a sprocket pulley downward through a retaining clamp and over a second pulley at the bottom and winding reel. The film passes over both sprocket pulleys at a uniform speed, between a stationary and swinging, clamp operated automatically from the shaft of the shutter and holds the film stationary when the opening of the shutter is behind the lens, during the interval the picture is projected on the screen. The clamp is then released, then the pivoted lever below, with a roller on the upper end and pulled inward at the other end by a spring, immediately takes up the slack (as shown by the dotted lines), and causes, by such sudden movement, the bringing of the next picture into position.
There are several plans for making the quick change necessary. That designed by Lumiere Brothers, of France, is said to be one of the most compact. The film is carried forward intermittently by a pawl and ratchet movement.
The effect of these enlarged pictures in motion on the screen is very pleasing and novel, those we have seen illustrating marching soldiers, railway trains approaching a station, street episodes, ocean surf, Niagara Falls, bathing scenes, dancing girls, and the life in aquariums being remarkably natural and effective.
Worked in unison with the phonograph, it may be possible in the near future to reproduce an opera, illustrating each movement of the actors, including the grimaces and peculiar expressions of their faces, assisting greatly thereby the understanding of the phonographic music.
What other possibilities may be in store for these twin instruments remains for future developments to determine. The kinetoscope stereopticon may certainly be set down as one of the novel improvements for the year 1896.