176 SPECIAL SENSES. 



most facility. Imagine this tuning-fork vibrating in the free 

 air. At the end of a second from the time it commenced its 

 vibrations, the foremost wave would have reached a distance 

 of 1,090 feet in air of the freezing temperature. In the air of 

 this room, which has a temperature of about 15 C., it would 

 reach a distance of 1,120 in a second. In this distance, there- 

 fore, are embraced 384 sonorous waves. Dividing, therefore, 

 1,120 by 384, we find the length of each wave to be nearly 

 3 feet." 1 



By the siren, the principle of which is simple and suffi- 

 ciently easy of comprehension, we can measure, with mathe- 

 matical accuracy, the number of vibrations executed by any 

 body emitting a simple musical tone, and we thereby arrive 

 at an absolute demonstration of the fact, that a tone in music 

 is composed of equable waves of sound, and that, the higher 

 the tone, the more rapid are the sonorous vibrations. 



Musical /Scale. We have thus far considered simple mu- 

 sical tones, without any reference to the relations of different 

 tones to each other. A knowledge of these relations lies at 

 *he foundation of the science of music ; and, without a clear 

 idea of certain of the fundamental laws of music, we cannot 

 thoroughly comprehend the mechanism of audition. 



It requires very little cultivation of the ear to enable us 

 to comprehend the fact, that the successions and combinations 

 of tones must obey certain fixed laws ; and, long before these 

 laws were the subject of mathematical demonstration, the re- 

 lations of the different notes of the scale were established, 

 merely because certain successions and combinations were 

 agreeable to the ear, while others were discordant and ap- 

 parently unnatural. Now that we are pretty thoroughly ac- 

 quainted with the laws of vibrations, we can study the scale 

 from a scientific, as well as an aesthetic point of view.. 



The most convenient tones for our study are those pro- 

 duced by vibrating strings, and the phenomena here ob- 



1 TYNDALL, Sound., London, 1867, p. 68. 



