504 lEVING HARDESTY 



1, 2, 3 and 4. The note c ( Wddle C/ 261 vibrations per second) 

 produced vibrations in regions 1 and 2 but none in the other 

 regions, regardless of ampUtude. Judging from the preceding, 

 this note was expected to give vibrations in region 3 at least and 

 I was unable to determine a reason for its not doing so. Also 

 the notes d and e (294 and 329 vibrations per second respectively) 

 gave vibrations in region 1 but not in the other regions, and the 

 note / (349 vibrations per second) at greatest amplitude gave in 

 region 1 only a slight hum in the telephone. Notes with vibra- 

 tion frequencies above that of / produced no evidences of vibra- 

 tion in the model. The note / and the three or four notes above 

 / that were tried produced appreciable vibrations in the artificial 

 tympanic membrane. 



Beginning with the note h, the signal-marker ceased to be of 

 service with the higher vibration frequencies. At times it would 

 start vibrating at the first puff of the air through the reed and 

 then become silent though a continuous hum might be heard 

 in the telephone. The fact that notes c and d, e and / could not 

 be made to give more graded results must have been due to 

 imperfections in the construction of the model. Perhaps the 

 intervals of the membrane arranged for were not short enough. 

 However, such results as were obtained seem to indicate a 

 relation between the vibration frequency of sounds and the 

 extents of the membrane thrown into vibration by them. In 

 explanation of this may be mentioned the familiar fact that of 

 sounds given the same amplitude, those of lower vibration fre- 

 quency are damped out less quickly in their transmission through 

 a medium, or will travel farther, than those of higher frequency. 

 For example, fog-horns of low vibration frequency or pitch are 

 known to be more efficient for warnings at a distance. Also 

 in atmosphere, sounds of high vibration frequency are not only 

 sooner damped out in overcoming resistance than those of low 

 frequency, but their speed of transmission decreases more rapidly 

 as they become fainter. This damping out must occur much 

 more quickly in transmission through a medium like the endo- 

 lymph than in atmosphere and in overcoming the resistance 



