76 BELL SYSTEM TECHNICAL JOURNAL 



in the theater from one or more sound-tracks. A variation of approxi- 

 mately one octave in the control frequency provides a 30-db change in 

 volume range which may be used in part for volume expansion of loud 

 sounds or as noise reduction for weak sounds. The control-track frequency 

 is varied manually and recorded simultaneously with the sound-track in 

 the dubbing operation, the gain of the monitoring channel being varied 

 in accordance with the control frequency to produce automatically the 

 enhanced volume range desired from the release print. The track is 

 recorded in line with the standard soundtrack and does not require separate 

 printing or reproducing apertures. It is scanned by a separate photo- 

 sensitive surface, the output being converted from frequency to voltage 

 variations by a frequency-discriminating network identical to that used in 

 the monitoring channel. The output from the network, applied to the 

 grid of a variable-gain-amplifier in the sound channel, controls automatically 

 the volume of the reproduced sound in accordance with that observed in 

 the dubbing operation. 



Performance oj Ground-Relayed Distribution Circuits during Faults to 

 Ground? C. L. Gilkeson, P. A. Jeanne and J. C. Davenport, Jr. An 

 extensive oscillographic study has been made on power distribution feeders 

 primarily to obtain data useful in the consideration of joint use of poles by 

 power and telephone facilities. Some of the results, chiefly those obtained 

 from three-phase, four-wire, multigrounded neutral feeders equipped with 

 instantaneous ground relays and for immediate breaker reclosure, are 

 believed to be of general interest and are presented herewith. Included 

 are data on the performance of the protective devices utilized for clearing 

 ground faults on the feeders included in the study, the effectiveness and 

 certain limitations of these devices, and characteristics of the faults ex- 

 perienced. 



A More Symmetrical Fourier Analysis Applied to Transmission Problems.* 

 R. V. L. Hartley. The Fourier identity is here expressed in a more sym- 

 metrical form which leads to certain analogies between the function of the 

 original variable and its transform. Also it permits a function of time, for 

 example, to be analyzed into two independent sets of sinusoidal components, 

 one of which is represented in terms of positive frequencies, and the other 

 of negative. The steady-state treatment of transmission problems in 

 terms of this analysis is similar to the familiar ones and may be carried out 

 either in terms of real quantities or of complex exponentials. In the 

 transient treatment, use is made of the analogies referred to above, and 



' Elec. Engg., Transactions Section, January 1942. 

 * Proc. LR.E., March 1942. 



