Vibration Curves of Violin Bridge and Strings. 461 



violin in use, shows by chalk-marks on the belly the positions 

 of (1) the bass bar and (2) the sound-post. The former is a 

 little bar of wood glued inside the belly and lying under the 

 space between the G and D strings and extending almost 

 the whole length of the belly. The position of the sound- 

 post is shown by the circle under the E string and just below 

 the corresponding foot of the bridge. The sound-post is a 

 little straight piece of wood extending from the belly to the 

 back of the violin, and held in place simply by the pressure and 

 consequent friction. In this view the optical lever is again 

 shown slightly displaced and tied to the strings, the adjustable 

 bracket being still in position. 



Results. 



The results obtained are exhibited in Pis. VIII. & IX. 

 by the 72 photographs, which naturally fall into four groups 

 or series according to the motion of the bridge concerned 

 and the corner of it under examination. The violin was the 

 one used in the former paper, and the strings were in this 

 work used " open " and always at concert pitch. The cir- 

 cumstances under which each photographic record was 

 obtained are briefly indicated at the margin against each 

 print. The place of excitation of the string is indicated by 

 the fraction of its length from the bridge at which it was 

 bowed, plucked, or struck. " Plucked " indicates plucked 

 with the finger-tip ; " struck " indicates the use of a pencil 

 with several thicknesses of washleather, to form a soft pad ; 

 the plectrum referred to as sometimes used in plucking was 

 simply a pencil-point. The " wooden hammer " referred to 

 is simply the pencil without the pad. The strings not in use 

 were still in position and at concert pitch. They were in 

 their equilibrium position if behind that in use, but if in 

 front they were tied down to the neck as though being- 

 stopped by the lingers as in playing. We may now note 

 various special points in connexion with some of the indi- 

 vidual prints. 



Vertical Motion of E-string corner of Bridge. (Upper part 

 of PL VIII.) — Figs. 1 and 2 show the G-string's motion to be 

 of small vertical amplitude but with Fourier's series to 

 infinity, the bridge's motion being of very large amplitude 

 and of quite different character. The two show by their 

 general similarity the satisfactory working of the experi- 

 mental arrangements, which remarks apply likewise to the 

 next three figures (3-5) ; here, however, the curves for the 

 string are rounded, as the forcing of the bow is absent. 



