Page:Popular Science Monthly Volume 89.djvu/81

 Experimenting with the Phonoscribe

���This 7nachine is sometimes re- ferred lo as a "phonoscribe." It is designed to lake dictation, writing words down on paper in natural characters as fast as spoken. It is of interest here us a forerunner of the voice-operated typewriter. The man at the right is pronouncing the word "boat" as an example. The being silent, produces no effect on

���in boat, the machine, since it must necessarily spell words phonetically, or as they sound. The "bot" sound vibrations proceed into the transmitter and affect an electric circuit in which are 12 'inbrating-mirror mechan- isms. Detail of these is given in the figure below. Each mechanism is tuned by the small coils back of it so that it will only respond to vibrations, or cycles, of a certain magnitude. See page 70 for further description.

The black rectangles beneath the word "(Boat)" at right make clearer the workings of the selenium cell shown in the picture above. They may be

��considered a series of instantaneous views of the selenium cell while the light beams are varying in length over its surface. The white strips in the center of each view show how much the light beams happened lo be vibrating at each particular instant. The white curves connecting the bottoms and lops of these strips of course have no real existence but were drawn in lo show how the light-beam lengths follow the original shape of the word "boat" as sketched in, in front of the man's face. \ole also how the curve traced by the solenoid and pen varied directly with the length of these light-beams, tracing the identical curve.

��TUNED MAGNETIC STRIP

��MIRROi

��TUNED MAGNETIC STRIP

REFLECTED LIGHT BEAM

SELENIUM CELL

���CRANK-PIN O 004 EROM CENTER LINE OF SHAFT

��BLANK SPACE ■NS \6HADE

TukOiTEN OR OTHER POINT USHT DIRECT LIGHT BEAM CRANK-PIN GERMAN SILVER CONNECTING ROD

��Detail of mirror-muiinf^ mechanism. ."Similar lo a telephone receiver in general construction, the tuned magitetic strip taking the place of the usual diaphragm. Attached to the strip is a short lever working a liny crank-shaft on which a little mirror

��is mounted. \'ibralions Irom thr \lrtp rotate the crank slightly causing the mirror lo move through a small arc and throw its beam of light up and down OH a selenium cell in the manner shown in the illii^trnlion at the top of the page.

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