ARTICLES BY BELL SYSTEM AUTHORS 467 



for a thin electron beam. Corresponding parameters for a thick electron beam 

 are found by finding a thin beam with approximately the same r-f admit- 

 tance. 



Effect of Change of Scale on Sintering Phenomena* C. Herring.^ //., 

 Applied Phys., V. 21, pp. 301-303, April, 1950. 



Abstract — It is shown that when certain plausible assumptions are ful- 

 filled simple scaling laws govern the times required to produce, by sintering 

 at a given temperature, geometrically similar changes in two or more sys- 

 tems of solid particles which are identical geometrically except for a differ- 

 ence of scale. It is suggested that experimental studies of the effect of such 

 a change of scale may prove valuable in identifying the predominant mech- 

 anism responsible for sintering under any particular set of conditions, and 

 may also help to decide certain fundamental questions in fields such as 

 creep and crystal growth. 



Mode Conversion Losses in Transmission of Circular Electric Waves Through 

 Slightly Non-Cylindrical Guides* S. P. Morgan, Jr.^ //., Applied Phys., 

 V. 21, pp. 329-338, April, 1950. 



Abstract — A general expression is derived for the effective attenuation 

 of circular electric (TEoi) waves owing to mode conversions in a section of 

 wave guide whose shape deviates slightly in any specified manner from a 

 perfect circular cylinder. Numerical results are in good agreement with ex- 

 periment for the special case of transmission through an elliptically deformed 

 section of pipe. The case of random distortions in a long wave guide line is 

 analyzed and it is calculated, under certain simplifying assumptions, that 

 mode conversions in a 4.732-inch copper pipe whose radius deviates by 1 

 mil rms from that of an average cylinder will increase the attenuation of the 

 TEoi mode at 3.2 cm by an amount equal to 20% of the theoretical copper 

 losses. The dependence on frequency of mode conversion losses in such a 

 guide is discussed. 



Acoustical Designing in Architecture. C. M. Harris^ and V. O. Knudsen. 

 Book, New York, John Wiley & Sons, Inc., 450 pages, 1950. 



Abstract — This book is intended as a practical guide to good acoustical 

 designing in architecture. It is written primarily for architects, students of 

 architecture, and all others who wish a non-mathematical but comprehensive 

 treatise on this subject. Useful design data have been presented in such a 

 manner that the text can serve as a convenient handbook in the solution 

 of most problems encountered in architectural acoustics. 



*A reprint of this article may be obtained on request to the editor of the B. S.T.J. 

 ' B.T.L. 



