Abstracts of Recent Technical Papers from 

 Bell System Sources 



Complex Magnetization} Eugene Peterson. Magnetization of 

 silicon steel by two sinusoidal fields of dififering frequencies. The 

 energy loss W per cycle and the flux density B associated with each 

 of the two frequencies were determined when the two sinusoidal 

 magnetizing forces were simultaneously impressed on a toroidal 

 silicon steel core built up of one-mil laminations. A null method 

 was used which permitted suppression of the modulated currents 

 and constancy of the impressed currents during manipulation for 

 balance. The frequencies used were 400, 821 and 1582. Six sets of 

 measurements were taken with fixed magnetizing forces ranging 

 from 0.5 to 10 gilberts /cm and superposed forces up to 15 gilberts /cm. 

 The results show that the effect of superposition depends upon the 

 relatixe amplitudes and upon the frequency ratio R of the superposed 

 frequency to the other. At low fixed fields W and B go through 

 maxima as the superposed field is increased, the maximum value 

 increasing with R. The maximum is less pronounced or absent for 

 the higher fixed fields. In general B is smaller with a low than with 

 a high value of R other things being equal. The effect on IT is not 

 as sharply defined ; in general the eft'ect of superposition is more pro- 

 nounced the higher the superposed frequency. The amplitude effect 

 and frequency ratio effect are shown to be in general agreement with 

 conclusions drawn from mathematical treatment of somewhat simpli- 

 fied cases and it is concluded that the effects are not inconsistent 

 with purely hysteretic phenomena. 



Some Photographic Problems Encountered in the Transmission of 

 Pictures by Electricity} Herbert E. Ives. This paper considers 

 some of the problems of photographic tone reproduction, which arise 

 upon the introduction of an electrical transmission system between 

 a picture placed on sending apparatus in one place and the copy ot 

 the picture made by receiving apparatus in another place. Some of 

 these problems arise because of limitations introduced by the use 

 of the electrical transmission line; others arise because of opportunities 

 for the control of picture qualit\- which are not afforded by ordinary 

 photographic methods. As an illustration of one of these limitations 



1 Physical Review, Vol. 27, pp. 318-328, March, 1926. 



^Journal of the Optical Society of America and Review of Scientific Instruments, 

 xMarch, 1926, pp. 173-194. 



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