16 



by the circular open tube, each 

 closed tube absorbes a -f wave, 

 and hence, notwithstanding that 

 there is so much vibrating mate- 

 rial, no sound is heard. But if 

 the tubes A and Bwere open, then 

 the vibrating centres should 

 have been simply transferred to 

 their farther extremities, and the 

 tubes would emit sound as the 

 fork had done without them in 

 the preceding figure. 



If the open tube be double the length of a phase, then 



the neutralization oc- 

 . / curs as in the figure, 

 the residual waves 

 being b and f, in op- 

 posite phases ; but 

 as their centres are 

 separated so far, they interfere only in hyperboloidal planes, 

 which are not detected unless when carefully sought for, but 

 have been noticed to exist by Savart, although he did not 

 suspect their cause. 



All these principles have received very full verification 

 from an instrument constructed for the purpose, and termed 

 a Chorizophone. It consists of a square glass plate, which 

 is placed above a set of closed tubes of such size, that when 

 the plate vibrates in four pieces, with diagonal nodal lines, 

 the length of each tube is half the length of the phase of the 

 wave produced, and their form is triangular, of the magnitude 

 of one of the four vibrating portions of the plate ; when one 

 of these tubes is presented to the plate, and this brought to 

 vibrate by a violin bow applied to the centre of one of the 

 sides, the tube resounds, and more loudly in proportion as the 

 plate is brought nearer to its orifice. Now here the entire 



