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stitution of matter has been much more fully investigated 

 than has yet been done. 



The motions produced by elasticity are generally very 

 small, and as many of the motions of sonorous bodies are 

 of this nature, some of the peculiarities of such small 

 motions demand attention ; amongst the most remarkable 

 of these we shall find that a very large mass of matter 

 may be put in vibratory motion by a very small force ; for 

 instance, a very slight stroke will make a large bell sound ; 

 showing that although vibratory motion is not altogether 

 freed from the obstacle of vis inertioe^ yet the vis inertioe 

 is easily overcome, from the circumstance that a small num- 

 ber of particles are at first moved, and then communicate 

 their motions from one to another ; and in vibratory motion 

 the particles of matter move upon each other almost without 

 friction. 



Another important property of vibratory motion, is that 

 of accumulation from a continuance of the vibratory force ; 

 thus a very heavy pendulum may be set in motion by an 

 apparently very inadequate force, applied in accordance 

 with its time of vibration. 



Again, vibratory motion communicates itself with remark- 

 able freedom to all the particles of the vibratory body, 

 which are in a relative vibratory position ; thus, if one side 

 of a glass goblet be struck, the vibration is instantly com- 

 municated to the other side. 



If a solid body be struck in almost any manner, vibration 

 will result, and will communicate itself to the air, so that 

 sound will be heard. If the body struck be so circumstanced 

 that it cannot vibrate freely, and maintain a succession of 

 regular vibrations, the sound produced will be what is called 

 noise ; but if the body can vibrate regularly, and continue 

 its vibrations at a rate exceeding sixteen pulsations in each 

 second of time, a musical tone will be produced, more or less 



