Page:Popular Science Monthly Volume 91.djvu/49

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Popular Science Monthly


��Lost in New York? Consult an Electri- fied Street Directory

THE man from Oshkosh or Paducah can easily find his way around New York city if he happens to stop at one of the thirteen hotels there which have in- stalled the electric directory. He can'find the location any building, street, or carline by pushing an electric button on the keyboard, for the location he is seeking will be il- luminated by a little six-volt incandes- cent lamp.

The directory board is sixteen square feet in area and the map is di- vided into fifty-six sections for the city of greater New York. The current for the board is furnished by storage batteries.

���When the right button is pushed the desired location flashes into view

��Taking Records of Sounds by Wireless for Talking Motion Pictures

THE problem of making talking motion pictures has been attacked by many inventors, but no more ingenious sugges- tion than that of Mr. William B. Vansize has been brought, out. According to Mr. Vansize's plan, each actor is equipped with a tiny wireless telephone transmitter, and his speech is sent through the ether by "radio" to a receiving station which is


���The wiring diagram of the apparatus which is worn by the actor. An oscillating vacuum tube supplies high-frequency current

��connected with the phonograph. The receiv- ing station may be located some distance from the actors and camera, so that as the people move about the stage their distances from the radio receiver will re- main relatively unchanged and their words will always be heard at about the same strength.

An oscillating vac- uum tube will supply the necessary high fre- quency current, and the batteries used to run it may be made of very small size. A ground con- nection is secured through contacts placed on the soles of the actor's shoes and arranged to touch a metal plate on the stage; the diminutive aerial re- quired may be con- structed of a few thin wires projecting upward a foot or two above the actor's head, or may merely be a sheet of thin metal foil fastened across his shoulders under his coat. The micro- phone transmitter which his voice operates need not be visible, for it has long been known that the vibrations of one's chest are amply strong enough to operate a tele- phone transmitter held over the lungs.

The wireless waves sent out by each actor's radio telephone transmitter pass over the space separating the stage from the receiving station, which may be several thousand feet away, and there affect a very sensitive wireless detector. This instrument converts the speech waves into telephone currents, which are carried back to the recording phono- graph by a wire telephone line. The sound-recording in- strument may be either a magnetically controlled wax cylinder phonograph or a "telegraphone," which latter uses a thin steel wire instead of a soft cylinder or disk, and makes its sound records mag- netically. Whatever type of recorder is used, it is mechani- cally connected with the mov- ing picturf camera.

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