248 BELL SYSTEM TECHNICAL JOURNAL 



stimulation on the basilar membrane has been calculated from data on 

 differential pitch sensitivity. The calculations involve assumptions 

 concerning the choice of the upper and lower pitch limits of hearing and 

 the choice of tone levels which should be used in obtaining differential 

 pitch sensitivity data. It is shown that for quite different assumptions 

 the positions of stimulation for tones in the range from 500 to 10,000 

 cycles are not greatly affected. Outside this range the positions 

 depend on the assumptions. The calculated positions for tones of 

 1000, 2000 and 4000 cycles fall, respectively, at points on the membrane 

 about \, I and f of its length away from the helicotrema. The calcu- 

 lated positions are compared with positions obtained from post-mortem 

 studies of human cochlea and with positions obtained from electric 

 response measurements on the cochlea of anesthetized guinea pigs. 

 The differences between various methods for the most part are no 

 larger than calculated differences between observers. 



Some Uses of the Torque Magnetometer.'^ H. J. Williams. The 

 history of torque measurement as an index of ferromagnetic anisotropy 

 is outlined. A simple magnetometer for torque measurement is de- 

 scribed in detail and uses for the instrument are discussed. These 

 include the measurement of anisotropy constants, coercive force, com- 

 plete magnetization curves for single directions, and rotational hys- 

 teresis losses. With auxiliary ballistic measurement residual induc- 

 tions and demagnetizing factors are obtainable. 



■• Rev. Scientific Instruments, February, 1937. 



