Instruments as Resonators. 125 



In the trombone and the euphonion we have two instru- 

 ments of very different and characteristic qualities of tones — 

 the trombone being brilliant and piercing, and the euphonion 

 mellow. We may take the B|? of about 120 vibrations (army 

 pitch) on each of these and endeavour to give a visible proof 

 of the existence of high upper partial tones. For this purpose 

 I use small tubular resonators covered at one end with a tightly 

 strained diaphragm or tympanum of goldbeater's skin, against 

 the centre of which is hung a very small bead, or drop of 

 sealing-wax, by means of a single thread of cocoon-silk. The 

 two resonators now used are tuned respectively to the fourth 

 and ninth partials of Bb, or b f b of 480 vibrations and c'" of 

 1024. When the proper tone of such a resonator is sounded 

 in its neighbourhood, either as a simple tone or as a partial in 

 a compound tone, the agitation of the membrane puts the bead 

 in violent motion, which can easily be seen in the image thrown 

 on the screen by the electric lamp. It will be noticed that 

 when B[? is sounded, either on the euphonion or on the trom- 

 bone, both resonators are agitated — but that the excursions of 

 the bead due to the partial tone of 1024 vibrations are much 

 greater with the latter than with the former instrument, 

 although both are played with but moderate force, thus 

 proving that, though partials as high as the ninth exist in the 

 quality of tone produced by both these instruments, yet in the 

 trombone the upper partials have much greater strength than 

 in the euphonion. With a resonator more suitable for private 

 experiment than these, I have distinctly heard the sixteenth 

 partial tone in the B[? of the trombone. A tapering tube open 

 at both ends, or a common wine-bottle with the bottom knocked 

 out, is very convenient for analyzing tones. Sinking such a 

 tube in water and holding the ear close against the small end, 

 the various partials existing in a given compound tone may be 

 readily discerned, as the length of the tube changes according 

 to the depth it is immersed in the water. 



Although one wind instrument may be made to approach 

 another in quality of tone by means of different methods of 

 blowing, and it is therefore not so easy to analyze the tones of 

 these as it is those of keyed instruments with fixed tones, yet 

 I have endeavoured to establish some general data ; and these I 

 will lay before you. The instruments the tones of which I 

 have analyzed are the B^ tenor trombone, the B\> euphonion, 

 the F French horn, the B\> cornet, and the bugle. The par- 

 tial tones named in the Table are those heard when the instru- 

 ments are gently blown ; with loud blowing higher tones can 

 be discerned. The ordinary marks of musical expression, pp, 

 p, nif,f, are added in cases where I found it possible to make 

 a comparison. 



