Transmission of Musical Sounds. 235 



9. 



In the preceding experiments on the transmission of sound 

 through solid bodies, the conductors have been represented as 

 straight; but, though sound is transmitted the more readily 

 through straight conductors, it will yet pass, though with 

 diminished intensity, through rods with angular and curved 

 bendings. If a vibrating tuning-fork be placed at one end of 

 a straight brass rod, the other end of which rests perpendicu- 

 larly upon a sounding-board, the vibrations will, in accordance 

 with what has been above stated, be powerfully transmitted ; 

 on gradually bending the rod at any part of its length, while 

 the vibrations of the tuning-fork are kept in the same plane 

 with the angle of the bent rod, the transmitted sound will pro- 

 gressively decrease in intensity, and will be very feeble when 

 the angle has become a right one : as the bending is continued 

 so as to make the angle between the two parts of the rod more 

 acute, the intensity of the sound will increase in the same 

 order in which it had before diminished ; and when the two 

 parts of the rod are nearly parallel, the sound will be nearly as 

 loud as when the transmission was rectilineal. If, during the 

 gradual bending of the rod, the plane of the vibrations of the 

 tuning-fork be perpendicular to the plane of the angle made 

 by the two parts of the rod, the same changes will be observed, 

 but in a more obvious manner, than in the former case ; and 

 when the angle becomes a right one, the sound will be scarcely 

 perceptible. At intermediate inclinations of the two planes, 

 the gradations of intensity, occasioned by the bending of the 

 rod, will be found to be intermediate. 



The changes of intensity dependent on the variation of the 

 angle of the two planes may be instructively shewn by bending 

 the rod permanently to a right angle, and placing, as before, 

 the stem of a tuning-fork so as to form the prolongation of one 

 of the parts of the rod, the other part of the rod resting on the 

 sounding-board. On gradually turning the tuning-fork round 

 the axis of its stem, without inclining it to the rod, the plane 

 of the vibrations will assume every angle with respect to the 

 plane in which the two parts of the rod is bent. During the 

 revolution it will be observed, that when the planes coincide 



