174 BELL SYSTEM TECHNICAL JOURNAL 



on timbre are still lacking there is no doubt that similar results will be 

 found for timbre, namely, that although it depends principally upon 

 the overtone structure, nevertheless, changes in fundamental frequency 

 and changes in the intensity also produce large changes in the timbre. 



Ceramics in the Telephone.'^ A. G. Johnson and L. I. Shaw. In 

 this descriptive paper by Western Electric engineers the problems of 

 ceramic materials as they relate to telephone usage are discussed. 

 New products with specific properties include every type of ceramic 

 material — electrical porcelain, vitreous enameled parts, glass and 

 heavy clay products. Manufacturing problems of the above materials 

 are discussed. 



La Transformation Triangle — Etoile pour des Elements de Circuits 

 Generaux.^ John Riordan. This paper gives the relations between 

 the constants of linear passive transducers connected in star and delta. 

 The delta-star transformation previously given by Lavanchy (Revue 

 Generale de VElectricite, XXXVI, pp. Il-v31 and 51-59) is shown to 

 admit a slight generalization, perhaps of little practical importance. 

 In the reverse (star-delta) transformation (not previously given), three 

 of the nine independent constants of the three transducers are shown 

 to be defined uniquely, but of the remaining six, three may be defined 

 at pleasure, subject only to dimensional and cyclic requirements . This 

 lack of uniqueness is shown concordant with the connection conditions. 



Flutter in Sound Records.^ T. E. Shea, W. A. MacNair, and Y. 

 SuBRizi. Frequency modulation of a sound signal is caused by non- 

 uniformity in the record speed during the recording or reproducing 

 process. This source of flutter is discussed and was demonstrated at 

 the May 1935 Convention of the Society of Motion Picture Engineers. 



The paper includes a discussion of the physical nature of freque ncy 

 modulation, the physiological effects of frequency modulation, the 

 methods of producing known amounts of artificial flutter, and the 

 methods of measuring flutter. 



Acoustic Impedance of Small Orifices.'' L. J. Sivian. Data are 

 presented giving the measured acoustic reactance and resistance for a 

 number of circular orifices varying in diameter from 1 cm. down to 

 0.034 cm., and for a rectangular orifice 1.9 cm. X 0.075 cm. The 

 measurements were made for various particle velocities, the cor- 



* Indus, and Engg. Chemistry, November, 1935. 



* Revue Generale de I'&ledricitc, September 21, 1935. 

 « Jour. S. M. P. E., November, 1935. 



' Jour. Acous. Soc. Amcr., October, 1935. 



