Abstracts of Bell System Technical Papers Not 

 Appearing in this Journal 



Thermal Agitation in Conductors} H. Nyquist. At the December, 

 1926, meeting of the American Physical Society, J. B. Johnson re- 

 ported the discovery and measurement of an e.m.f. due to the thermal 

 agitation in conductors. The present paper outlines a theoretical 

 derivation of this effect. A non-dissipative transmission line is 

 brought into thermodynamic equilibrium with conductors of a definite 

 temperature. The line is then isolated and its energy investigated 

 statistically. The resultant formula is E^-dv = 4kTRdv for the 

 r.m.s. e.m.f. E^ contributed in a frequency range one cycle wide by a 

 network whose resistance component at the frequency v is R. T and 

 k are the absolute temperature and the Boltzmann constant. Experi- 

 mental data are available for the audible range and there the agreement 

 between the formula and the data is good. It will be observed that 

 neither the charge nor mass nor any other property of the carrier of 

 electricity enters the formula explicitly. They enter indirectly 

 through R. The formula above is based on the equipartition law. 

 If the quantum distribution law is used, the expression becomes 



E,~dp = [4hpR/\e'"'i''^ - l)]dv. 



The two expressions are indistinguishable in the range of the measure- 

 ments. 



Light Waves in Metals} Thornton C, Fry. When a wave of 

 plane polarized light falls obliquely upon a conducting surface, it 

 gives rise to a disturbance inside the conductor which has, among 

 others, the following peculiarities: 



(a) It is neither plane nor elliptically polarized, but belongs to a 

 third distinct category; 



{h) It does not travel with what is customarily called "the speed 

 of light"; 



(f) Its velocity varies with the angle of incidence. 



There are similar light waves in dielectrics and in free space. 



Transatlantic Telephony.^ F. B. Jewett. This paper discusses 

 in rather popular terms some of the outstanding problems which 

 1 Phys. Rev., Vol. 29, p. 614, April, 1927. 

 - Opt. Soc. Amer. JL, Vol. 14, p. 473, June, 1927. 

 3 Scientific Monthly, August, 1927. 



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