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KENNELLY-TAYLOR— EXPLORATIONS OVER [April 22, 



is then suspended on wires from the ceiling, or other convenient 

 support, in order to suppress building vibrations of high frequency ; 

 so as to support the explored diaphragm in a vertical plane. The 

 mirror-holder is then advanced towards the diaphragm, and clamped 

 by screw S. The mirror is now carefully brought into contact with 

 the surface of the diaphragm by adjusting screw M. A picture of 

 the explorer is presented in Fig. 4. The suspension wires zvzu, 



Fig. 4. Vibration Explorer in Booth. 



support the instrument. The condensing and focusing lens H 

 throws a narrow arc-light beam upon the exploring mirror, which 

 reflects it on to the translucent graduated screen F. With the dia- 

 phragm at rest, the spot on this screen is a narrow, sharp, vertical, 

 luminous strip. When the diaphragm is set in vibration, the mirror 

 in contact with it vibrates synchronously, and the spot is spread 

 into a luminous band, the limits of which are easily read on the 

 graduated translucent scale. If the motions of diaphragm and mirror 

 are simple harmonic motions, the luminous band shows no discontinu- 

 ities of intensity. If, however, there is a complex harmonic motion 

 in the diaphragm, the luminous band will show bright and dark 



