ABSTRACTS OF RECENT TECHNICAL BOOKS 369 



Tb, Dy, Ho, Er, Th, Yb and Lu. These measurements showed the 

 rare earth elements, without exception, to be more active thermion- 

 ically than the commonly occurring metals. At 1800° C. all of 

 these metals gave emissions of more than 10'^ that of clean tungsten 

 at the same temperature. 



The So! id us Line in the Lead Antimony System.^ Earle E. Schu- 

 macher and Foster C. Nix. An investigation of the solidus line 

 above the solid solution field for the lead antimony system was made 

 by the quenching test procedure. Three points were determined 

 between the melting point of pure lead and the end of the eutectic 

 horizontal. The position of the solidus line has been precisely fixed. 



Production ControlJ C. G. Stole. This paper treats the subject of 

 production control from the practical rather than the theoretical point 

 of view. It is confined largely to a description of the generally accepted 

 principles of production control as applied in the Manufacturing 

 Department of the Western Electric Company. This plant employs 

 approximately 30,000 people and produces annually over $150,000,000 

 worth of manufactured products. These products are comprised of 

 some 13,000 kinds of apparatus containing over 110,000 different parts. 



The paper discusses the organization of the factory, which is set 

 up along functional lines, and also the extensive system of records 

 and charts used to facilitate the work of the organization and to assist 

 in production control. 



The Significance of the Dielectric Constant of a Mixture.^ Homer 

 H. LowRY. It is pointed out that in many cases it would be of 

 great value to be able to calculate either the dielectric constant of a 

 mixture of substances of known dielectric constants or, knowing the 

 dielectric constants of a mixture of two components and that of one 

 of the components, to calculate the dielectric constant of the other. 

 A review of the literature, however, shows that this can be rarely 

 accomplished. This is due mainly to the inadequacy of the theories 

 of dielectrics, all of which are insuf^ciently developed to include the 

 dielectric behavior of mixtures. Nevertheless, as is shown, many 

 attempts have been made to develop formulae of theoretical significance 

 for application to mixtures. Inspection of the derivation of these 

 formula^ shows that those with the best theoretical background are 

 limited to such special cases that they are of practically no value. 



6 A. I. M. E. Pamphlet No. 1636-E, Feb. 19, 1927. 

 ^ Mechanical Engineering, Vol. 49, p. 201, 1927. 

 ^ Jr. of the Franl?!in Institute, 203, 413-439, 1927. 



