Abstracts of Technical Articles from Bell System Sources 



A Loud Speaker Good to Tivelve Thousand Cycles} L. G. Bostwick. 

 A loud speaker, designed for use as an adjunct to existing types of 

 speakers to permit efficient sound radiation at the higher audible 

 frequencies, is described. The structural and performance character- 

 istics are indicated, and some of the advantages and limitations of 

 such a loud speaker are discussed. 



Indicating Meter for Measurement and Analysis of Noiser T. G. 

 Castner, E. Dietze, G. T. Stanton, and R. S. Tucker. This 

 paper describes a visual indicating meter for the measurement of 

 noise and other sounds. Its design is based on the known character- 

 istics of sound and hearing, which are summarized. Particular 

 attention has been paid to the response of the meter to sounds of 

 short duration. The aim has been to make the meter both simple in 

 operation and portable. An attachment for the frequency analysis 

 of noise is under development. Several fields of use of the meter 

 and analyzer are indicated. 



Some Applications of Bell System Instrumentalities and Practice to 

 Railroad Communication Problems.^ F. A. Cowan. Railroad com- 

 munication problems are fundamentally similar to those encountered 

 in the Bell System. As a result, the instrumentalities and practices 

 developed for telephone company use are, to a large extent, applicable 

 to railroad company use. Suitable Bell System circuits and equipment 

 have, therefore, been made available to the railroad companies. 

 Likewise, by means of representation on the American Railway 

 Association committees, and by participation in conventions and joint 

 discussions wherever practicable, information regarding many of the 

 more general telephone company practices has been incorporated in 

 the Railway Association codes. 



There are, of course, some conditions which are peculiar to railroad 

 operating procedure or plant. In these cases existing Bell System 

 instrumentalities have been adapted for use, or new equipment suited 

 to the particular cases involved has been developed. Catalogues and 

 papers listing and describing this special equipment, together with 



1 Jour. S. M. P. E., May, 1931. 



2 Published in abridged form in Elec. Engg., May, 1931. 

 ^ Proc. Amer. Railway Assoc, Sept., 1930. 



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