TRENDS IN PRACTISE AS AFFECTING COORDINATION 165 



Probably the most fundamental and far reacliiiii; of these changes is 

 the progress of conversion from manual to dial system operation. 

 When present plans are completed this will result in the operation of 

 approximately 80 per cent of the telephones of the Bell System on a 

 dial basis, and a large part of the existing manual central ofifice equip- 

 ment will have been removed from service. \Mth the application of 

 the dial system there is a trend toward a greater concentration of cen- 

 tral office equipment in one building, so that in the future as many as 

 100,000 telephones may be switched by the various central office units 

 in a single building. While these trends are of the greatest and most 

 fundamental importance from the standpoint of the development of 

 the telephone business they do not atTect the coordination problem in 

 any material way and therefore need not be further discussed here. 



An important trend in telephone practise has been the provision of 

 apparatus designed for higher standards of service and greater con- 

 venience for use at the customer's station. This includes the hand set, 

 new types of private branch exchanges and of auxiliary telephone 

 station apparatus, and improvements of transmission characteristics. 

 These changes in some respects affect the coordination problem and 

 these effects are indicated below. 



Another important fundamental change in the telephone plant and 

 one of great importance from the coordination standpoint is the rapid 

 extension of new types of facilities for toll circuits, that is, long distance 

 and interurban circuits whose use involves what is called a toll charge. 

 These changes and their effects on the coordination problem are dis- 

 cussed in this paper. 



One of the most spectacular trends of development of the Bell System 

 at the present time is the increase in the number of connections to 

 foreign countries. Earlier connections to Canada and Cuba were 

 supplemented in 1927 by service to Mexico and by transoceanic radio 

 links providing service from New York to London, through which 

 connection is made to the principal European countries; and in 1930 a 

 similar radio link from New York to Buenos Aires through which con- 

 nection is made to Montevideo, Uruguay, and Santiago, Chile. Dur- 

 ing the next few years it is expected that these foreign connections will 

 increase to include generally all important points in South Amenca, 

 Australia, Japan, Honolulu and all other points which may offer an 

 appreciable demand for service. 



These intercontinental circuits are not of such character and location 

 as to be directly affected by the physical proximity of power circuits, 

 but their efficiency is affected by the noise currents on connected cir- 

 cuits in the same way as other very long circuits are affected and this is 

 discussed briefly below. 



