1/8 THE SPEECH OF MONKEYS. 



which have given me some very strange phe- 

 nomena. I dictate to the phonograph a vowel in 

 different keys while the cylinder rotates at a 

 given rate of speed. I then adjust the speed to 

 a certain higher or lower rate and follow the re- 

 sults. By reversing the motion of the cylinder 

 the sounds are reduced to their fundamental 

 state. By this means we eliminate all familiar 

 intonation and disassociate it from any meaning 

 which will sway the mind, and in this way it can 

 be studied to advantage. At a given rate of 

 speed I have taken the record of certain sounds 

 made by a monkey, and by reducing the rate of 

 speed from two hundred revolutions per minute 

 to forty, it can be seen that I increased the in- 

 tervals between what are called the sound-waves 

 and magnified the wave itself five-fold, at the 

 same time reducing the pitch in like degree, and 

 by this means I could detect the slightest shades of 

 modulation. I may remind the reader here that in 

 this process all parts of the sound are magnified 

 alike in all directions, so that instead of obtain- 

 ing five times the length, as it were, of the sound- 

 unit or interval, we obtain the cube of five times 

 the normal length of every unit of the sound. 

 The slightest variation of tension in the vocal 



