State of Experimental Acoustics. 291 



and certainty a phenomenon which only presents itself to dis- 

 appear again. These intermittent phenomena are generally 

 produced by an effort, often requiring considerable skill. 

 Under these circumstances there is a tendency to accept the 

 first conclusion that comes to hand, the mind being to some 

 extent satisfied with the production of the difficult pheno- 

 menon. Again it has become perhaps too much the practice 

 to refer the phenomena to optical analysis or analogy. In 

 some cases this reference is, no doubt, most convenient ; in 

 other cases it is misleading. It is requisite that the analysis 

 of the perceptions of the ear be conducted by reference to the 

 ear itself. 



The only form of apparatus in use for the production of 

 simple tones in a continuous manner depends on the applica- 

 tion to resonators of tuning-forks driven by electromagnets. 

 These are in many respects ill adapted for demonstration, 

 though no doubt they have furnished most valuable results. 

 There appears to be a want of adaptability about the apparatus; 

 and it is very costly. Professor Konig is probably better ac- 

 quainted with the practical use of this apparatus than any one 

 else, except perhaps Helmholtz himself; and Konig has, in an 

 elaborate analysis of the phenomena *, controverted the entire 

 foundations of the work of Helmholtz. Opinions are by no 

 means at one on the subject, even amongst the highest autho- 

 rities. 



With the object of improving the treatment of this part of 

 the subject, I have introduced resonators which speak in the 

 manner of organ-pipes. These resonators are easily managed 

 with a little simple organ-mechanism ; they receive their wind 

 through flexible tubes, and can be placed in any part of the 

 room, at any distance apart, &c. — a matter of great importance 

 in facilitating the analysis of the phenomena. The resonators 

 are fitted with siphons and reservoirs ; by a simple contrivance 

 of this kind they can be tuned to any note within range at a 

 moment's notice. 



These resonators are made out of bottles, corks, and metal 

 organ-pipes. Their cost is trifling. 



The notes should be perfectly pure tones, according to the 

 theory, having regard only to disturbances of the smallest 

 order: but practically, in all tones of this supposed pure cha- 

 racter small quantities of harmonics do exist ; and I have long 

 maintained that they always must exist in sensible intensity, 

 on account of the transforming power of the air, or, in other 



* Pogg. Ann. clvii. p. 177 ; Phil. Mag. [V.] i. pp. 417, 511. See also 

 1 Proceedings of Musical Association/ 1878-79, Spottiswoode " On Beats 

 and Combination-tones." 



