282 BELL SYSTEM TECHNICAL JOURNAL 



follows laws which are particularly amenable to mathematical study; 

 partly also to the fact that so much of the research has been centralized 

 in a single laboratory, thus bringing together a large number of engineers 

 into a single compact group, and justifying the employment of consultative 

 specialists. Most important of all, however, is the fact that there are two 

 devices — vacuum tubes and electrical networks — without which modern 

 long-distance telephony would be impossible; and one of these, the electrical 

 network, is and has been since its earliest days almost entirely a product of 

 mathematical research. Mathematics has thus been as essential to the 

 development of nation-wide telephony as copper wire or carbon microphones. 



Number of Mathematicians. The Mathematical Research Department of 

 the Bell Telephone Laboratories contains 14 mathematicians. Perhaps 

 an equal number of men scattered through various engineering departments 

 should also be classified as mathematicians according to the definition 

 adopted for this report. Say a total of 25 or 30 for the Bell Laboratories, a 

 few more for the Bell System as a whole, and perhaps 40 or 50 for the entire 

 communication field including the companies interested in radio and 

 television. A few of these men carry on a considerable amount of experi- 

 mentation, but their significant work is theoretical. 



In addition, there is a much larger number of men who use mathematical 

 methods extensively in their daily work, but whose mental type is not that 

 which we have described as mathematical, and who are therefore not in- 

 cluded in the numbers quoted above. This is true in particular of the 

 engineers who have the responsibility for designing networks. 



Uses of Mathematics. Mathematical activity is most intense: (1) in 

 designing wave filters and equalizers, (2) in studying transmission by 

 wire and ether, the concomitant problems of antenna radiation and recep- 

 tion, inductive interference between lines, etc., (3) in studying various 

 problems related to the standard of service in telephone exchanges, such as 

 the amount of equipment required, the probability of delays and double 

 connections, the hunting time of switches, etc., (4) in providing a rational 

 basis for the design of instruments, such as transmitters and receivers, 

 vacuum tubes, television scanning devices, etc., (5) in developing efficient 

 statistical methods for the planning and interpretation of experiments, and 

 for controlling the quality of manufactured apparatus. 



Future Prospects. During the last 20 years the number of men employed 

 in communication research has increased with great rapidity, but this rapid 

 expansion appears to be about over. A large increase in the mathematical 

 personnel of the industry therefore appears unlikely. It seems inevitable 

 that the problems will increase in complexity, and that theoretical methods 



