ABSTRACTS OF TECHNICAL ARTICLES 671 



cal conductor there is a statistical variation of the electrical potential 

 difference between its two ends which is due to the thermal agitation 

 of the atoms, including the electrons. This electrical noise is amplified 

 by means of a vacuum tube amplifier and then converted into an 

 acoustical noise by means of a telephone receiver held on the ear. 

 When this noise is present it reduces the capability of the ear to hear 

 other sounds. The intensity per cycle of the acoustical noise compared 

 to the intensity of a pure tone which can just be perceived in the pres- 

 ence of a noise was determined experimentally using a group of ob- 

 servers. This relative intensity for a given frequency range was 

 constant throughout a wide variation of intensity. However, its 

 value does vary with the position in the frequency spectrum and it is 

 the amount of this variation which enables one to calculate the relation 

 between the frequency of the tone and its position of maximum stimula- 

 tion along the basilar membrane. The results of such a calculation 

 are given and shown to be in good agreement with determinations from 

 animal experimentation. 



Transcontinental Telephone Lines} J.J. Pilliod. A fourth trans- 

 continental line has just been created by the completion of four pairs 

 of open wire between Oklahoma City and Whitewater, California. 

 This open-wire line connects at its eastern terminus with the already 

 existing toll cables from the east, and at its western terminus with a 

 toll cable running into Los Angeles. 



In a cross-section of the United States just west of Denver, there 

 are now 140 through telephone circuits and about the same number 

 of telegraph circuits carried by four open-wire routes. 



The four new pairs which constitute the transcontinental line carry, 

 in addition to the usual voice frequency channels, three channels of 

 carrier. But their design throughout has been such that twelve 

 additional carrier circuits can be superimposed upon the four channels 

 now provided by each wire pair. 



The wires of each pair are spaced 8 inches apart with the nearest 

 spacing between pairs being 26" while crossarms are 36" apart. New 

 transposition systems have also been used to further reduce crosstalk. 



Application of Statistical Methods to Manufacturing Problems} W. 

 A. Shewhart. The application of statistical methods in mass produc- 

 tion makes possible the most efficient use of raw materials and manu- 

 facturing processes, effects economies in production, and makes 

 possible the highest economic standards of quality for the manufac- 

 tured goods used by all of us. The story of the application, however, 



^ Electrical Engineering, October 1938. 

 * Jour. Franklin Institute, August 1938. 



