.tnsTR.icTs or pull system technical p.-wi-L'S 179 



an- iiiis\innu'trir.il with rfspoot l<> tlio /i-ro of maniu'tic fii-ld is illiis- 

 tratwl ami the (li'tfctii)n of such dissyinnictrj' is discussetl. 



.1 Classijifd List of Published fiibliog,raphies in Physics, 1!)IQ-1!)22} 

 Kari, K. Darrow. This work, uncicrtaken at tlic request of the 

 National Research C"ouiicil, represents an attempt to cope with tlic 

 proMeni of providing a con\enient and adequate hihlionraphy of 

 physics, not by actually writing a complete classified hiiiliograplA' 

 (which would fill a huge volume and retjuire the prolonged lalK)r of 

 sc\eral men), but b\- listing the very numerous partial bibliographies 

 under a detailed subject-classification. Many of the accounts of 

 research publishetl in scientific journals contain short histories of the 

 previous work in the subjects which they treat, many others contain 

 lists of references, and there are also a number of critical or uncritical 

 reviews of particular fields with thorough documentations. The 

 Classified List of Published Biblioiiraphies refers to all of these which 

 appeared in any of the familiar physical journals between 1910 and 

 1022 inclusively, and a numlxr of books as well; it is believed that 

 almost every article upon a physical subject, which has ever been cited 

 or reviewed in another article, can be traced through the List. The 

 system of classification, in which the field of physics is divided into 

 seventy-five classes with numerous sulxlivisions, is much the most 

 detailetl and elaborate which has been made out for the science of 

 physics in a score of years. An adequate system of classification is of 

 great value in any science, for researches which are clasified under 

 it are not only made easy to trace, but their various aspects and their 

 mutual relations can be emphasized. Because of the rapid growth 

 and evolution of physics, the earlier systems have mostly become 

 inadequate; but it is hoped to make and keep this system effectiv^e 

 by constant attention and revision, and to e.xtend the use of it. 



Transmitting Equipment for Radio Telephone Broadcasting.* 

 Edw.vrd L. Nelson. The general transmission considerations apply- 

 ing to any system for the high quality transmission of speech or music 

 are outlined briefl\-, and the specific requirements to be met by the 

 various apparatus uniti in a radio broadcasting equipment are dis- 

 cussed in some detail. The standard Western Electric 500-watt 

 broadcasting equipment, which has found application in some fift>' of 

 the larger stations in this country and abroad, is described. Its per- 

 formance capabilities are illustrated and it is indicated that a standard 

 of performance has been attained which renders possible reproductions 

 not substantially different from the original. 



' Bulletin of the .National Research Council, No. 47. 



• Proc. of The Inst, of Radio Engineers, Vol. XII, page 553, 1924. 



