Instruments as Resonators, 127 



illustration of the first of these conditions the trombone may 

 be compared with the euphonion ; the tubing of the trombone 

 is cylindrical for about two thirds of its length from the mouth- 

 piece, but the euphonion opens with gradually increasing cur- 

 vature from the mouthpiece to the rim of the bell. The high 

 upper partials being more powerful on the former than on the 

 latter instrument, it would appear that the cylindrical tubing- 

 has the power of maintaining the intensity of the short waves 

 to a greater extent than the tapering tubing has. The bell- 

 flange may be increased in size to a considerable degree with- 

 out altering the pitch of an instrument ; but such increase has 

 a marked effect on the quality of tone, greatly subduing the 

 force of the upper partials. I find by experiment that the pitch 

 is not altered by the extension of the flange curvature beyond 

 a point at which its tangent would make an angle of about 40° 

 with the axis of the instrument, although the quality of tone 

 is decidedly altered by such extension. This may be illustrated 

 by changing the bell-end of a bugle for a bell with much wider 

 flange, more like that of a French horn : comparing the two, 

 it will be noticed that the change in quality of tone is very 

 marked. 



The form of the cup of the mouthpiece varies for different 

 instruments, from that of a long deep conical funnel to that of 

 a comparatively shallow well-rounded cup — the first form 

 representing the French-horn mouthpiece, and the second the 

 mouthpiece for instruments of brilliant tone, as the trumpet 

 and trombone; those for cornets, bugles, and saxhorns are of 

 an intermediate character. Although it is manifest that a 

 shallow cupped mouthpiece favours the production of high 

 upper partials, I have not as yet succeeded in arranging any 

 experiments which would illustrate the cause of this. One 

 fact, however, noticed by many observers, appears to me to be 

 suggestive, and worth bearing in mind in connexion with this 

 subject. It is this : — If a vibrating tuning-fork be placed on 

 a sounding-board, the quality of tone it gives varies with the 

 pressure applied : touching the board very lightly with the 

 fork the prime tone is well heard ; but on pressing the fork 

 down to the board the tone appears to jump up an octave ; at 

 least the second partial (octave of the prime) is heard with 

 great distinctness. This experiment appears to prove that if 

 an elastic resonant body (in this case the resonant board) is in 

 a state of initial pressure at the point of origin of vibrations, 

 a vibration that would otherwise be simply pendular becomes 

 a vibration compounded of two or more simple pendular vi- 

 brations. Applying this consideration to wind instruments, 

 and bearing in mind the initial pressure caused by the escape 



