104 



KENNELLY-TAYLOR— EXP].ORATIONS OVER [April 22, 



An organ-pipe of Z?* (608^ — ^) was set up with its lip 5 cm. from 

 the back of the diaphragm. An exploration was then made over the 

 surface, at points differing by 40° in azimuth Q, and at successive 

 increases in radius of about 3.3 mm. (7 steps in r, and 9 steps in Q, 

 or d^i observations in all.) The preceding table gives the observed 

 amplitudes of vibration deduced from the scale-deflections, with a 

 magnification factor of M= 1,180. 



It will be seen from the above table, that at any particular 

 radius r, measured from the center of the diaphragm, the amplitudes 

 at varying azimuths 6 are substantially equal. The irregularities 

 are small, but nevertheless seem larger than can be accounted for 

 by errors in observations and are, perhaps, due to irregularities in 

 the diaphragm. Fig. 7 shows the contour lines of vibration-ampli- 

 tude in microns, the maximum amplitude being at or near the 

 center, and amounting to 14 /a. Such vibration amplitudes are 

 larger than were usually obtained, and were specially reinforced in 

 this case, in order to secure large deflections. It will be seen from 

 the contour diagram, that the diaphragm was vibrating with its 

 fundamental or gravest mode of motion; i. e., a motion to-and-fro 

 as a whole, without either nodal diameters or nodal circles. It is 

 known that a circular diaphragm, clamped at the edge, is capable of 

 vibrating in an indefinitely large number of ways, according to the 



Fig. 7. 



VrBf?ATioN Amplitude 



IN MlCF?ONS. 



608/V 

 DiAPHf?AGM No. I. 



Fig. 8. 



Vibration Amplitude 



IN MICRONS. 



Z\00 rj. 



DlAPHf?AGM No.l. 



