446 Prof. Barton and Mr. Penzer on Simultaneo- 



us 



1 



hja 



8 



1/100. 

 0-5159 



1/10. 

 4-059 



1/5. 

 6299 



1/4. 

 7-209 



i 



1/2. 



10-38 



3/4. 

 12-34 



1. 



13-59 



o 



16-15 







hja 



8 



3. 

 1722 



4. 

 17-80 



5. 

 18-16 



6. 

 18-41 



7. 

 18-59 



8. 

 18-73 



9. 



18-84 



10. 

 18-91 





When h is greater than 40a we may write 

 L = 19-74(1 -4«/37rA)(a7/0N 2 j 



(50) 



and when h is greater than 400a, we get the well-known 

 formula 



L = 19'74(a 2 /A)N 2 . 



XXXIV. Simultaneous Vibration- Curves of Siring and Bridge 

 photographically obtained from a Monochord. By E. H. 

 Babton, D.Sc, F.JR.S.E., Professor of Experimental 

 Physics, and J. Penzer, Research Scholar, University 

 College, Nottingham* . 



[Plates XI. & XII.] 



PEEYIOUS papers in this series have dealt with (i.) the 

 belly f and string, and (ii.) the air J and string; the 

 present communication gives the results experimentally 

 obtained for the bridge and string of the same monochord. 

 The motions of the bridge are recorded vertically and hori- 

 zontally, the string being excited both by bowing and 

 plucking. Examples of beats are also obtained by using in 

 addition to the vibrations of the string those of a tuning- 

 fork placed upon the instrument. In the later figures curves 

 are shown for the bridge and string when the latter is 

 weighted in the middle so as to make its partial tones 

 inharmonic. 



Experimental Arrangements. — The string's motion is ob- 

 tained and recorded as in the previous papers. The bridge's 

 vertical motion is detected and photographed by the rocking 

 motion of an optical lever, as in the case of the motion of 

 the belly in the first paper. These effects are shown in 

 figs. 1-6 & figs. 14-26 (Plate XI.), in which the string's 



* Communicated by the Authors. 



t Barton & Garrett, Phil. Mao-. July 1905. 



+ Barton & Penzer, Phil. Mag. Dec." 1906. 



