1258 THE BELL SYSTEM TECHI^^ICAL JOURkAL, SEPTEMBER 1953 



if J is the exchange integral, can be compared with observed line breadths by 

 estimating J from Curie-Weiss constants for a number of materials. The 

 results are quite satisfactory if the theory is extended in two ways: (a) When 

 the exchange frequency is larger than the resonance frequency, it can be 

 shown that the off-diagonal elements of the dipolar interaction must be in- 

 cluded, leading to a line-width larger by a factor of roughly 10/3; (b) in a 

 number of cases hyperfine and Stark splitting is contributing importantly to 

 the width. 



The good agreement with experiment in the cases we have investigated 

 leads us to believe that a quantitative approach to the paramagnetic reso- 

 nance line breadth problem, using only the already known concepts of dipolar 

 interaction, exchange narrowing, and fine structure splitting, will probably 

 explain all the observed phenomena. 



Andrus, J., see J. K. Galt. 



Arnold, S. M., see Miss S. E. Koonce. 



Benedict, T. S./ and W. Shockley^ 



Microwave Observation of the Collision Frequency of Electrons in 

 Germanium, Letter to the Editor. Phys. Rev., 89, pp. 1152-1153, 

 Mar. 1, 1953. 



BiES, F. R} 



Attenuation Equalizers, Audio Eng. Soc. J., 1, pp. 125-136, Jan., 1953. 



In all systems there are components which attenuate some frequencies to a 

 greater extent than others, and attenuation equalizers are usually required 

 to correct the overall gain-frequency characteristic. This paper will deal 

 with the types of attenuation equalizer that are found most useful, the per- 

 formance that they display, and a chart method of computing their insertion 

 loss. 



Bozorth, R. M.^ 



PermaUoy Problem, Revs. Mod. Phys., 25, pp. 42-48, Jan., 1953 

 (Monograph 2102). 



In attempting to explain the unusual magnetic properties of the iron-nickel 

 alloys, single crystals of alloys containing 35 to 100 per cent nickel were 

 prepared, and measurements made of the magnetic crystal anisotropy and 

 magnetostriction as dependent on cooling rate. It is confirmed that there is a 

 large effect of cooling rate on the anisotropy in the region near FeNia, but 

 the experiments show also a substantial effect between 50 and 85 per cent 

 '"ckel. Two magnetostriction constants, Xioo and Xm, were measured on the 



« Bell Telephone Laboratories. 



