Technical Articles by Bell System Authors Not Appearing 

 in the Bell System Technical Journal 



Measurement Method for Picture Tubes. M. W. Baldwin.^ Electronics, 

 V. 22, pp. 104-105, Nov., 1949. 



Diffusion in. Binary AIloys.'\ J. Bardeen.^ Phys. Rev., V. 76, pp. 1403- 

 1405, Nov. 1, 1949. 



Abstract — Darken has given a phenomenological theory of diffusion in 

 binary alloys based on the assumption that each constituent diffuses inde- 

 pendently relative to a fixed reference frame. It is shown that diffusion via 

 vacant lattice sites leads to Darken's equations if it is assumed that the 

 concentration of vacant sites is in thermal equilibrium. Grain boundaries 

 and dislocations may act as sources and sinks for vacant sites and act to 

 maintain equilibrium. The modifications required in the equations if the 

 vacant sites are not in equilibrium are discussed. 



Variable Phase-Shift Frequency-Modulated Oscillator. 0. E. de Lange.^ 

 I.R.E., Proc, V. 37, pp. 1328-1331, Nov., 1949. 



Abstract — The theory of operation of a phase-shift type of oscillator is 

 discussed briefly. This oscillator consists of a broad-band amplifier, the out- 

 put of which is fed back to the input through an electronic phase-shifting 

 circuit. The instantaneous frequency is controlled by the phase shift through 

 this latter circuit. True FM is obtained in that frequency deviation is 

 directly proportional to the instantaneous amplitude of the modulating sig- 

 nal and substantially independent of modulation frequency. 



A practical oscillator using this circuit at 65 mc is described. 



Erosion of Electrical Contacts on Make.\ L. H. Germer^ and F. E. Ha- 

 woRTH.i //. Applied Phys., V. 20, pp. 1085-1108, Nov., 1949. 



Abstract — When an electric current is established by bringing two elec- 

 trodes together, they necessarily discharge a capacity. Unless the current 

 which is set up is above 1 ampere, the erosion which is produced in a low 

 voltage circuit is appreciable only when the capacity is of appreciable size 

 and when it is discharged very rapidly by an arc. When the arc occurs, its 

 energy is dissipated almost entirely upon the positive electrode and, when 

 the circuit inductance is sufficiently low, melts out a crater intermediate in 

 volume between the volume of metal which can be melted by the energy 



t A reprint of this article may be obtained on request to the editor of the B. S.T.J. 

 1 B.T.L. 



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