400 Professor G. H. Bryan [March 10, 



paradoxical. A sudden short, sharp cut-off of the pneumatic tension 

 often causes a note to " sing out " when it would not do so otherwise. 

 What appears to me most remarkable is the amount of difference that 

 it is possible to make even in comparatively short chords. 



In the case of a repeated treble note with bass accompaniment, 

 the second time it is struck accentuation is more difficult, and there 

 is considerable danger of the note failing to sound owing to the 

 bridge between the two notes buckling, thus continuously admitting 

 air to the primary valves, and preventing the piano action from 

 returning to its normal position. The best plan is to keep the 

 tension low till the chord containing the repeated note has passed 

 the tracker board, and then force the notes down hard. This appears 

 to project the hammer of the repeated treble note at the second 

 period of its ascent and often causes it to ring out above the bass. 

 This action is exactly the reverse of what is necessary in the case of 

 a non-repeated note. On account of the additional difficulty thus 

 incurred in reading the music, I believe that it would be justifial)le 

 to cut the troublesome note a little after the accompanying chord, 

 much as I object to this plan in other cases. 



In order to understand the device by which these differences of 

 effect can be easily produced, it will be necessary to have a clear 

 idea of the working of the regulating bellows and accent lever which 

 is to be found in different modified forms in almost every pneumatic 

 player. In addition to the suction bellows which generate the 

 vacuum, there is a large reservoir bellows, controlled by springs, 

 w^hich acts as an accumulator or condenser of considerable capacity. 

 But between this part of the instrument and the playing pneumatics 

 two channels of communication usually exist. One is through an 

 accent valve A controlled by a lever (and in many modern instru- 

 ments there is a third passage through an accent valve operated by 

 punch-holes in the music). The other connection is through a 

 smallish regulating bellows, which I will call B, controlled usually by 

 a spring, and through an air valve connected with this bellows which 

 opens or closes with it according to the degree of vacuum. This 

 arrangement is sometimes called a " choker," or " equahzer," since its 

 statical action tends to counteract any increase or decrease in the 

 pressure of the air which is being withdrawn from the playing 

 pneumatics. 



Now it will be found that in playing the regulating bellows is in 

 a continual state of vibration, and that this vibration has a very 

 marked effect upon the tone-quality and expression. If it is 

 attempted to produce accentuation and other effects by means of the 

 accent valve and pedalling, the effects are liable to be largely modified 

 by the induced vibrations (if I may so call them) set up in the 

 bellows. 



The patented device used in my experiments, and subsequently 

 made by the Motomusic Co., Edinburgh, consists in controlling this. 



