ART. 10, — S. KUSAKABE. 



II. METHOD OF MEASUREMENT AND APPARATUS. 



The essence of Melde's experiment is that, on one hand, a 

 massive fork excited by a bow or sustained in permanent opera- 

 tion by an electro-magnet, j)roduces its vibrations in approximate 

 independence of the reactions of any light body, which may be 

 connected with it ; and, on the other hand, the period of the 

 forced vibration of the light body is determined solely by the 

 period of the force which is supposed to act on the system from 

 without. The principle of resonance is merely that the kinetic 

 energy or the amplitude of any forced vibration is the greatest 

 possible, when the period of the external force is that in which 

 the system would vibrate freely under the influence of its own 

 elasticity. 



The present method is simply as follows : — 



a. A specimen of rock, one end of which is tightly clamped 

 by a massive vice, is maintained in free vibration. 



b. A fine wire of known linear density w is connected with 

 the free end of the specimen and stretched with a known 



' tension. 

 c. The length I of the above wire, in which the wire vibrates 

 with maximum amplitude is measured. 

 The annexed figures show the plan and elevation of the 

 whole arrangement, which is laid directly on stone floor of the 

 laboratory. 



