Abstracts of Technical Articles from Bell System Sources 



Effects of Rectifiers on System Wave Shape} P. W. Blye and H. E. 

 Kent. Operation of mercury arc rectifiers generally results in in- 

 creased harmonic currents in the rectifier supply circuits and may re- 

 sult in increased harmonic voltages. While these harmonics usually 

 are not serious from the standpoint of the power system, they may 

 result in interference to communication circuits exposed to the power 

 circuits. This paper presents a method of computing these harmonic 

 voltages and currents, and discusses methods of coordinating telephone 

 systems and a-c. power systems supplying rectifiers. 



Joint Use of Poles with 6,900-Volt Lines} W. R. Bullard and D. 

 H. Keyes. a plan has been developed for joint occupancy of poles by 

 power and telephone circuits in the Staten Island, N. Y. area, involv- 

 ing 6,900-volt distribution. The aim of this plan is to secure to the 

 public and to the power and telephone companies over-all safety, 

 convenience, and economy. Results of this cooperative study of 

 joint use are presented in this paper. 



Sound Film Printing — //.'' J. Crabtree. The production of 

 sound-film prints from variable density negatives by the Model D 

 Bell & Howell printer has been studied from the point of view of high- 

 frequency response and uniformity of product. The account of this 

 study, begun in Part I, is continued here, with particular reference to 

 the degree of influence of slippage on the high-frequency response, 

 occasioned particularly by non-conformity of the perforation pitch 

 of the negative and positive films. It is found that to improve print- 

 ing conditions in practice, it is first necessary to achieve consistency in 

 the pitch of the processed negative and positive materials and to make 

 the pitch of the processed negative 0.0004 inch less than that of the 

 positive raw stock. 



The Determination of the Direction of Arrival of Short Radio Waves } 

 H. T. Friss, C. B. Feldman, and W. M. Sharpless. In this paper 

 are described methods and technique of measuring the direction with 



1 Elec. Engg., January, 1934. 

 ^ Elec. Engg., December, 1933. 

 3 Jour. S. M. P. E., February, 1934. 

 *Proc. I. R. E., January, 1934. 



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