390 BELL SYSTEM TECHNICAL JOURNAL 



optimum angle of flare. The possibility of forming arrays of pipes 

 or horns is mentioned. 



Hindered Molecular Rotation and the Dielectric Behavior of Condensed 

 Phases} Addison H. White. The polarizability of a liquid or a 

 collection of randomly oriented single crystals in which polar molecules 

 are unable to move except to rotate from one to the other of two 

 equilibrium orientations separated by an angle /i and of potential 

 energies whose difference is E, is 



a = {fxy6kT){]. - cos^)lcosh^EI2kT, 



where /x is dipole moment. This model accounts for the reduction of 

 a in solids and liquids from the value y?l^kT observed in gases, and 

 at the same time provides for anomalous dispersion in terms of dis- 

 continuous molecular processes. 



* Jour. Chemical Physics, January 1939. 



