Popular Science Monthly 



33 



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 



m 



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. 



