ABSTRACTS OF TECHNICAL ARTICLES 175 



responding Reynolds numbers varying from 0.7 to 3000, roughly. The 

 reactance is found substantially independent of the particle velocity; a 

 formula for computing it is given. The resistance approaches a con- 

 stant value as the velocity is sufficiently decreased; formulae for com- 

 puting this "low velocity" resistance are given. At larger velocities 

 the resistance increases with the velocity. This is discussed from the 

 standpoint of a loss of kinetic energy of flow, acting besides viscosity 

 and turbulence. 



Earth-Potential Measurements Made During the International Polar 

 Year.^ G. C. Southworth. Data are presented covering the normal 

 diurnal variation of earth-potentials as measured at about a dozen 

 different points, mostly m eastern United States. These data are 

 arranged in graphical form for the convenience of the casual reader and 

 also in numerical form for the use of the correlator. The data for 

 Wyanet (Illinois), Houlton (Maine), and New York (New York) are 

 based on nearly continuous recordings extending over a period of one 

 or two years. This period includes the International Polar Year. At 

 other points, less extensive data were taken. These show the general 

 characteristics peculiar to the location in question. 



The data taken at Wyanet, Houlton, and New York have been 

 analyzed for harmonic content. At New York the fundamental and 

 to a large extent the harmonics also, are directed along a northwest- 

 southeast line. At Wyanet and Houlton these components tend to 

 rotate with time. The pronounced directive effect noted near New 

 York appears to prevail rather generally along the eastern part of the 

 United States from Massachusetts to Florida and possibly into Cuba. 

 The rotary effect noted in the Houlton and Wyanet data is also found 

 in data taken in the southern part of the Mississippi Valley. Most of 

 the data point toward the generally accepted view that there is a close 

 relation between earth-resistivity and the direction and magnitude of 

 earth-potentials. However, there are some inconsistencies noted 

 which tend to make this less definite. 



The Characteristics of Sound Transmission in Rooms.^ E. C. Wente. 

 The characteristics of electrical circuits used for communication pur- 

 poses are advantageously determined from a measurement of the 

 transmission loss as a function of frequency. Similarly, a measure- 

 ment of the acoustic pressures at various points in a room while sound 

 of fixed intensity is emitted from a source should permit an evaluation 

 of the acoustic characteristics of the room. Measurements of this 



* Terrestrial Magnetism, September, 1935. 

 ^ Jour. Aeons. Soc. Amer., October, 1935. 



