TELEPHONE SYSTEM OF THE UNITED STATES 75 



two-way conversations between a moving plane and the wire telephone 

 system have been developed and demonstrated. 



Safety of airplane travel depends a great deal on the rapid accu- 

 mulation and dissemination of meteorological data. An experiment 

 on a promising method of handling such data is being carried out on 

 an airplane route between San Francisco and Los Angeles in the State 

 of California. At each terminal landing field and at two intermediate 

 fields meteorologists are located. At six periods during the day each 

 of these is rapidly connected in succession by telephone to outlying 

 weather observation points varying in number at the different points 

 from three to sixteen. The information thus accumulated and co- 

 ordinated at each of the four landing fields is rapidly transmitted to 

 the other three fields by means of printer telegraph circuits connect- 

 ing them. This constant rapid observation of weather conditions 

 along the airplane route and over a considerable territory around it 

 permits very accurate prediction of the weather conditions which 

 any plane will meet in its travel over the route. Such weather pre- 

 dictions may be communicated to the airplanes before starting or by 

 radio during their flight. 



Printer telegraph circuits appear to be a particularly convenient 

 means of interchanging information among important landing fields 

 along airplane routes. 



Ship-to-Shore Telephony 



The Bell System development work on ship-to-shore telephony was 

 originally started with wave-lengths in the neighborhood of 400 meters, 

 which were later taken into the broadcasting range. In 1920 shore 

 transmitting and receiving stations in northern New Jersey were 

 equipped to operate simultaneously three separate telephone channels 

 in this range. Through these radio stations any telephone subscriber 

 could be connected experimentally to the steamships " Gloucester" 

 and " Ontario " which were engaged in coastwise shipping from Boston 

 southward. In October, 1920, a talk to one of these ships furnished 

 an interesting part of a demonstration at a banquet in New York 

 City tendered to the delegates to the " Preliminary International 

 Communication Conference" which was meeting in Washington at 

 that time. 



Development of ship-to-shore telephony has been delayed because 

 of uncertainties regarding the commercial situation and wave-length 

 assignments. At the present time the work is again being actively 

 pushed using wave-lengths under 100 meters. A transmitting and a 

 receiving station will shortly be in course of construction near the 



