74 BELL SYSTEM TECHNICAL JOURNAL 



Electrical Transmission of Pictures 



A commercial service for the electrical transmission of pictures 

 between the cities of New York, Chicago and San Francisco was 

 inaugurated in April, 1925. The eight cities now connected to this 

 service and the routes of the lines used in connecting them are shown 

 in Fig. 56. In addition, a portable transmitter is provided which 

 may be moved to any desired point. At present this is located in 

 the city of Washington, D. C. 



The pictures as transmitted are of about twelve centimeters by 

 seventeen centimeters. Any size picture, of course, can be photo- 

 graphed to come within these dimensions. The detail of each picture 

 corresponds to 39.4 lines per centimeter in each direction, that is, 

 each picture is composed effectively of about v300,000 independent 

 elementary areas. The line time of transmission with the present 

 commercial system is about 7 minutes. 



Pictures may be sent from any of the cities shown to one or to 

 more of the other cities which are reached by this service. Newspapers 

 use this service for the transmission of pictures of events of national 

 importance or where matters arise in any part of the country of large 

 news interest. For example, pictures of the inauguration of President 

 Hoover were sent in this way to the newspapers in San Francisco. 

 In view of the three hours difference in time between Washington and 

 San Francisco the pictures were published in newspapers sold at a 

 time of day earlier than that at which the event took place. 



The majority of the pictures transmitted are for business or social 

 purposes including pictures of legal documents, advertising material 

 to be simultaneously released at a number of separate points, pictures 

 showing new styles in ladies' wearing apparel, personal greetings in 

 the handwriting of the sender and finger-prints of criminals. 



The Western Union and Postal Telegraph Companies now have a 

 service in which they will accept telegraph messages for " facsimile " 

 transmission over this picture system between those cities which the 

 system reaches. This service has not yet been offered long enough 

 to show how much it will be used. 



Telephony in Connection with Aircraft Operation 



Telephony promises to play a very important part in the practice 

 of commercial aviation. The Bell Telephone Laboratories are carry- 

 ing out a large amount of development work on all phases of telephony 

 for this purpose. One-way receiving sets have been developed per- 

 mitting an airplane pilot to receive weather reports and to determine 

 the direction of radio beacons. Experimental radio sets suitable for 



