We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
Talking Pictures
a "light valve." This is a metal box with a front and sides, but with no back. It is about the size of three small match boxes laid together sideways. Inside the box, forming the tiny slit between them, are two flattened duralumin wires which look like tiny ribbons placed edge to edge.
The current generated by the actors' voices reaching the stage microphone causes these wires to come closer together and to go wider apart. The movement of the wires varies the slit and permits the beam of light to pass through into a tightly closed rectangular box, through which a reel of film is moved very smoothly and uniformly and not with the interrupted "stop and go" motion of camera and projector. On an eighth-inch path of this film the beam, acting as a pencil of light, reduces all sounds to horizontal marks. On the finally developed film these marks have various gradations of black, white, and gray, but they are of constant width.
In the variable area method, the width of the sound track varies but its darkness is uniform. The current amplified from the microphone comes to a recording device which is almost identical with an ordinary galvanometer, a common device for measuring electrical current.
The galvanometer has two wires to which are attached a tiny mirror. When the current flows through the two wires in a magnetic field, the wires move somewhat as we have seen them in a "variable density" light valve. The movement, however, causes the mirror to rotate slightly and to reflect light against a narrow slit, the image of which is focused on the film. This pro
[198]