ABSTRACTS OF TECHNICAL ARTICLES 157 



1. During "all-daylight" path conditions, the usual multiplicity of 

 waves distributed in or near the great-circle plane, which constitutes 

 normal propagation, has been predominant. Usually neither iono- 

 sphere storms nor the catastrophic disturbances associated with short- 

 period fade-outs seem to affect the mode of propagation. 



2. In contrast to 1, during periods of dark or partially illuminated 

 path conditions, the great-circle plane no longer provides the sole 

 transmission path. The extent to which other paths are involved 

 varies greatly. Propagation during inosphere storms of moderate 

 intensity usually involves paths deviated to the south of the great 

 circle, during afternoon and evening hours. New York time. 



An Experimental Investigation of the Characteristics of Certain Types 

 of Noise. '^ Karl G. Jansky. The results of an investigation of the 

 effect of the band width on the efifective, average, and peak voltages 

 of several different types of noise are given for band widths up to 122 

 kilocycles. For atmospheric noise and that due to the thermal agita- 

 tion of electric charge in conductors, both of which consist of a large 

 number of overlapping pulses, the peak, average, and effective voltages 

 were all proportional to the square root of the band width. For very 

 sharp, widely separated, clean, noise pulses, the average voltage was 

 independent of the band width and the peak voltage was directly 

 proportional to the band width. For noise of a type falling between 

 these two the effect of the band width depended upon the extent of 

 the overlapping. 



The ratio of the peak to effective voltage of the noise due to the 

 thermal agitation of electric charge in conductors was measured and 

 found to be 4. The ratio of the average to effective voltage of this 

 type of noise was found to be 0.85. 



The experiments showed that when a linear rectifier, calibrated by 

 a continuous-wave signal having a known effective voltage, is used to 

 measure the effective voltage of this type of noise the measurements 

 should be increased by ]/2 decibel to obtain the correct result. 



Insulation of Telephone Wire with Paper Pulp} J. S. Little. The 

 paper presented here covers the history and development of wood 

 pulp insulation for telephone circuits. The development involved 

 the study of wood pulps and their preparation, the methods of applying 

 such pulp to wire, and the development of the necessary properties 

 within the insulation to make it suitable for telephone use. The use 



3 Proc. I. R. E., December 1939. 



* Wire and Wire Products, October 1939. 



