State of Experimental Acoustics. 297 



reeds from those in which the reeds are influenced by the re- 

 action of the resonator. This arrangement gives rise to a 

 beautiful set of experiments having many bearings. The 

 trouble of maintaining the constant motion of the turn-table 

 is very great ; and it is practically impossible to obtain definite 

 results without the uniform motor. 



This arrangement, where the stopcock delivers wind into a 

 pipe or resonator having the same vibration-frequency as that 

 of the jet of the stopcock, gives a smooth powerful tone : it is 

 well fitted for the evaluation of a sound of given loudness in 

 terms of mechanical energy. I shall return to this point. 



Strings. 



The conditions of the flow of sound-energy from strings, 

 through sound-boards, into the surrounding air require inves- 

 tigation. The case of practical interest is that of the violin. 

 By arranging a sort of skeleton so as to represent the principal 

 parts of the instrument, and employing mechanical bowing, 

 it is expected that some light may be thrown on this obscure 

 subject. This question is as yet untouched ; but it is probable 

 that the bridge and sound-post transmit a longitudinal vibra- 

 tion, which is communicated to the back at the point where it 

 meets the sound-post at right angles. The effect of " muting," 

 or loading the bridge with a small weight, comes in as a ques- 

 tion for explanation. 



Orchestral Instruments. 



The study of the theory of orchestral instruments is in its 

 infancy. The theory of the fingering of the wood wind — flute, 

 hautboy (oboe), clarionet, bassoon — appears likely to be for the 

 most part tolerably straight forward. The cases where two or 

 more segments of a tube affect each other, though there are 

 open holes between, form a problem which is untouched. 



The law that in all lip reed-instruments the note produced 

 is a resonance-note of the tube, was enunciated and proved 

 first by Mr. Blaikley (see ( Proceedings of the Musical Asso- 

 ciation,' 1877-78, p. 56). On the same occasion I stated that 

 I had obtained and proved the same law experimentally for 

 the hautboy and clarionet (I. c. p. 62). We may therefore take 

 as the basis of our work the proposition that, when reeds of 

 movable pitch form notes in combination with a variable reso- 

 nance, the note produced coincides with a note of resonance. 

 This is not true for reeds of fixed pitch associated with a reso- 

 nance, as in organ reed-pipes, according to the best practical 

 authorities. 



The study of the partial tones of columns of air, such as are 



