LIGHT AND SOUND 



Its rate of vibration varies from the minimum of 16 

 in a second, the lowest rate of audibility, to about 

 40,000 a second. The range of musical notes is 

 from 32 vibrations a second the lowest note of the 

 organ to 4224 vibrations, the upper notes of the 

 pianoforte, or 4752 of the picolo. The human voice 

 ranges from 87, for a bass voice, to 1530 a second, the 

 highest soprano. The length of the sound wave 

 varies inversely with the frequency of the vibrations; 

 a high note has a shorter length than a low one. The 

 average wave length in conversation, for a man's 

 voice is from eight and one-fourth, to ten feet ; for a 

 woman's voice from two to four feet. The relative 

 speeds, therefore, with which light travels through 

 the ether and sound through the air are : 



Light 186,000 miles in a second. 



Sound 1089 feet, or about one-fifth mile in a 

 second. 



Light travels, therefore, 907,000 times faster in 

 the ether than sound does in the air. 



The number of vibrations are inversely as their 

 length. The length of the vibrations of the violet 

 rays is fora> f an i nc h > the length of the vibra- 

 tions of the average waves of a woman's voice is 

 about three feet ; therefore the sound waves are four 

 million times longer than the waves of light. 



The number of the vibrations of violet light being 

 127 



