CHAP. III. 



STRINGED INSTRUMENTS. 



165 



understood, that is, what it is precisely which produces the sonorous 

 vibrations, and stops or prolongs them at will ; lessens or gives them 

 their full power. It will be seen that this mechanism is really very 

 simple. 



Below the strings are arranged hammers m, m, m, (Fig. 114), 

 which, when each key is at rest, remain side by side at a certain 

 distance from the double or triple string which corresponds to each of 

 them. By pressing down a key, that is to say, on lowering one arm 

 of the level* which constitutes the arrangement, another arm is raised 

 up ; the corresponding hammer is sent sharply in the vertical 

 direction, and strikes the corresponding string which then vibrates 

 under the influence of the blow. We must now see how this 

 movement of the hammer is effected, how it again falls after the 

 shock without rebounding, and without making any noise. Fig. 114 



FIG. 114. Piano : mechanism of the hammers and keys. 



explains the entire mechanism to us. Let us follow the series of 

 effects produced by the movement of pressing down the key. 



ab is the string, AOB the key resting on the point o. On pressing 

 B, the arm of the lever OA is raised, lifting an escapement G which 

 strikes the extremity e of the handle t of the hammer. This 

 hammer which is at first in the position M, then takes that of M', and 

 strikes the string which vibrates under the influence of the percussion. 

 But the escapement after having raised the hammer a certain height, 

 is itself stopped by a button placed obliquely ; it frees itself from the 

 head of the nut of the hammer which again resumes its first position 

 on a small bridge H, which is called the chair. This prevents the 

 hammer from rebounding, and deadens the noise that it would 

 otherwise make in falling. Let us add that the strings which produce 



