656 On the Pianoforte Sounding-Board. 



take these strings, another frame was made similar in con- 

 struction to the previous one but to take only two sections at 

 once, and is 187 cm. between the top and bottom beech planks. 

 The strings were all 84*7 cm. between the bridges except in 

 No. 25 where they were 89*4 cm. All were struck at ^. 



On section K 3 the bridge, instead of being near the middle, 

 was 22 cm. from the top or very nearly \ the length of the 

 section from that end. 



In No. 17 the 2nd partial is very strong, as would be 

 expected from the position of the bridge. 



In No. 18 the two strings had been pulled up three semi- 

 tones, which was as much as they would stand. The 2nd 

 partial is not quite so strong. 



In No. 19 a longer section K 8 was used, but owing to a 

 stronger bar there was little difference in the pitch from that 

 of K 3 . The bridge was 21 cm. from the top, which is less 

 than \ of the whole length 102 cm. 



In No. 20 the bar at back of section K 8 had been planed 

 down about 5 mm., reducing the natural frequency. The 

 tone was worse than in No. 19. The 3rd partial is prominent 

 in this case as well as the 2nd. Three times the natural pitch 

 of the section is nearly the pitch of the strings. 



In No. 21 the bridge has been moved to the middle of the 

 sounding-board. The 2nd partial is not nearly so marked 

 but is still easily seen and the tone was much better than that 

 of Nos. 17 and 18. 



The increased length of the sounding-board without a 

 corresponding increase in the thickness probably tends to 

 encourage the production of the upper partials. 



In I^os. 22-24: the strings had a heavier copper covering 

 in order to produce a lower note with the same length of 

 string. 



No. 22 shows a strong 2nd and marked 3rd partial, and 

 very little difference in the wave or tone occurred when the 

 strings were pulled up a tone. 



In No. 24 the bridge was moved down to the middle of the 

 sounding-board. The 2nd and other partials were very 

 marked and the tone was not good. 



No. 25 shows the last bass note. The long and weak 

 section Ksa did not give any good results. 



Conclusions. 

 The results of this investigation seem to indicate : — 

 (1) The vibrations of the sounding-board, when the bridge 



is near the middle, divide in half with a node at or near the 



middle. 



