512 THE BELL SYSTEM TECHNICAL JOURNAL, MARCH 1953 



practical circuit element. In particular, the reproducibility of units was poor — 

 units intended to be alike were not interchangeable in circuits; the rehability 

 was poor — in an uncomfortably large fraction of units made, the characteristics 

 changed suddenly and inexplicably; and the ''designability" was poor — it was 

 difficult to make devices to the wide range of desirable characteristics needed in 

 modern communications functions. This paper describes the progress that has 

 been made in reducing these limitations and extending the range of performance 

 and usefulness of transistors in communications systems. The conclusion is 

 drawn that for some system functions, particularly those requiring extreme 

 miniaturization in space and power as well as reHabiHty with respect to life and 

 ruggedness, transistors promise important advantages. 



In Search of the Missing 6 Dh. W. A. Munson^ and F. M. Wiener^ 

 Acoustical Soc, Am., JL, 24, pp. 498-501, Sept., 1952. (Monograph 

 2019). 



The unexplained difference in sound pressure in the ear canal which appears 

 to exist when equally loud low frequency tones are presented alternately from an 

 earphone and from a loudspeaker has bedeviled acousticians for many years and, 

 unfortunately, still continues to do so. There are presented here the results of 

 some of the measurements carried out at the Bell Telephone Laboratories which 

 show the magnitude of the effect and various attempts at explaining it. While 

 no satisfactory explanation has been found, it is hoped that publication of these 

 results will stimulate interest in the problem. 



Nation-Wide Numbering Plan. W. H. Nunn^. A.I.E.E., Trans., Com- 

 mun. and Electronics Sect., 2, pp. 257-260, Sept., 1952. Elec. Engg., 71, 

 pp. 884-888, Oct., 1952. (Monograph 2015). 



At the present time a great variation in the types of telephone numbers exists. 

 This is because of the number of telephones in communities of different sizes. 

 With the advent of local dialing and now nation-wide dialing, a uniform num- 

 bering system has become necessary. 



How to Detect the Type of an Assignable Cause. P. S. Olmstead^. Ind. 

 Quality Control, 9, pp. 32-34, 36, Nov., 1952. 



Silicon p-n Junction Alloy Diodes. G. L. Pearson^ and B. Sawyer^ 

 I.R.E., Proc, 40, pp. 1348-1351, Nov., 1952. 



A new type of p-n junction silicon diode has been prepared by alloying ac- 

 ceptor or donor impurities with n- or p-type silicon. The unique features of this 

 diode are: (a) reverse currents as low as 10~^° amperes, (b) rectification ratios as 

 high as 10* at 1 volt, (c) a Zener characteristic in which d(\og I) rf(log V) may 

 be as high as 1,500 over several decades of current, (d) a stable Zener voltage 



^ Bell Telephone Laboratories. 



2 American Telephone and Telegraph Company. 



