188 THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1957 



CONCLUSION 



The laying of the present repeatered transatlantic cable represents by 

 far the most ambitious use to date of long life, unattended electron tubes. 

 On this project alone there are 390 tubes operating on the ocean bottom. 

 If to this number are added the ocean bottom tubes from earlier shorter 

 systems, those used in the Alaskan cable completed a few months ago, 

 and those to be used in the California-Hawaiian cable to be laid in 1957, 

 the total number on the ocean bottom will be about one thousand. The 

 capital investment dependent on the satisfactory performance of these 

 tubes is probably about one hundred million dollars — ■ strong evidence 

 of faith in the ability to produce reliable and trustworthy tubes. 



It is of interest to note that the two groups working on the tubes on 

 opposite sides of the Atlantic had no intimate knowledge of each other's 

 work until after the tube designs had been w^ell established. As a result 

 of subsequent discussions, it has been surprising and gratifjdng to find 

 how similarly the two groups look at the problems of reliability of tubes 

 for submarine cables. 



The authors would be completely remiss if they did not mention the 

 contributions of others in the work just described. These projects would 

 have been impossible if it were not for the enthusiastic, cooperative and 

 careful efforts of many people working in varied fields. Over the years 

 chemists, physicists, electrical and mechanical engineers, laboratory 

 aides, shop supervisors and operators all have made essential contribu- 

 tions to the projects. It would be impractical and unfair to attempt to 

 single out for mention the work of specific individuals whose contribu- 

 tions are outstanding. There are too many. 



REFERENCES 



1. K. G. Compton, A. Mendizza and S. M. Arnold, Filamentary Growths on Metal 



Surfaces — "Whiskers," Corrosion, 7, pp. 327-334, Oct. "l951. 



2. M. Benjamin, The Influence of Impurities in the Core-Metal on the Thermionic 



Emission from Oxide-Coated Nickel, Phil. Mag. and Jl. of Science, 20, p. 1, 

 July, 1935. 



3. H. E. Kern and R. T. Lynch, Initial Emission and Life of a Planar-Type Diode 



as Related to the Effective Reducing Agent Content of the Cathode Nickel 

 (abstract only), Phys. Rev., 82, p. 574, May 15. 1951. 



4. G. H. Metson, S. Wagener, M. F. Holmes and M. R. Child, The Life of Oxide 



Cathodes in Modern Receiving Valves, Proceedings I.E.E., 99, Part III, p. 

 69, March, 1952. 



5. G. H. Metson and M. F. Holmes, Deterioration of Valve Performance Due to 



Growth of Interface Resistance, Post Office Electrical Engineers Journal, 46, 

 p. 193, Jan., 1954. 



6. M. R. Child, The Growth and Properties of Cathode Interface Layers in Re- 



ceiving Valves, Post Office Electrical Engineers Journal, 44, p. 176, Jan., 

 1952. 



7. G. H. Metson, A Study of the Long Term Emission Behaviour of an Oxide 



Coated Valve, Proceedings I.E.E., 102, Part B, p. 657, Sept., 1955. 



