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LXXXVIII. Simultaneous Vibration Curves for Strings and 

 Air of Violin. By Edwin H. Barton, ASc., F.R.S.E., 

 Professor of Experimental Physics, and Walter B. 

 Kilby, B.Sc, Research Scholar, University College, 

 Nottingham *. 



[Plates XIII.-XV.] 



(CONTINUING the work of one of us and others t, the 

 J present paper treats of the simultaneous motions of 

 the strings of a violin and the air at a sound-hole. In order 

 to detect the vibrations of the air, part of this sound-hole 

 was covered with a thin membrane connected to a rocking 

 mirror. 



Each string is dealt with separately and its vibrations 

 simultaneously with those of the air recorded photo- 

 graphically. Further, the strings were each excited at two 

 or more places by bowing, plucking, and striking. 



A special feature of the present work is the series of 

 photographs showing the initial stages of the motions. 

 Some of these figures record not only the musical vibrations 

 of the pitch of the string, but also the recoil and vibration 

 of the violin as a whole, just after the string was plucked or 

 otherwise excited. 



Experimental Arrangements. 



A general plan of the optical arrangements is given in 

 PL XIII. fig. 1. The light proceeds from the Leitz Lillipnt 

 Arc lamp A through the condenser C, in a nearly parallel 

 beam. Part of this beam falls upon a screen with a pinhole 

 H and proceeds thence to the small rocking mirror m (by 

 Hilger). This mirror is concave and converges the light 

 to the lower part of the photographic plate P. The other 

 part of the beam from the condenser is caught by the plane 

 mirror M 1? and sent to M 2 which reflects it to the slit S. A 

 real image of this vertical slit is then focussed upon the 

 string by the lens L A . The light is then reflected by the 

 plane mirror X, and a second real image is focussed by 

 the lens L 2 on the upper part of the plate P. This plate is 

 placed in the horizontal rails RR in a dark room, and in 

 Taking a photograph is shot along them by means of the 

 in diar libber cords shown. 



Thus the vertical vibrations of string and air combine 

 with the uniform horizontal motion of the plate to give two 



* Communicated bv the Authors. 



t Phil. Mapr. July 1005, pp . 149-157; Dec. 1906, pp. 576-578; April 

 1907, pp. 146-452; Aug; L 900, pp. .233-240 ; Sept. L910, pp. 156 \m. 



