122 Mr. D. J. Blaikley on Brass Wind 



the water-level when the tube is giving its maximum reso- 

 nance shows the position of the node. 



Brass instruments are generally considered to be cones, or 

 cones combined with cylindrical tubing, neither of which de- 

 scriptions properly applies ; and this I will endeavour to make 

 clear by experiment. We may, in the first place, consider 

 whether the resonance of cones and tubing is influenced ap- 

 preciably by the action of the lips ; and it will be found that, 

 whether the lips or a timing- fork be used to excite the vibra- 

 tion, the pitch is the same. Two illustrations may be given — 

 the first a common hunting-horn, pitch c 512 when it is 

 blown, and giving an excellent resonance to the c 512 fork 

 when the mouthpiece is closed ; if, however, we slightly alter 

 its length either way, the resonance to the fork is no longer at 

 its maximum. For the second illustration, I take a cylindrical 

 tube which becomes closed on being placed against the lips : 

 blowing it as a wind instrument, we find its proper tones are 

 c 128, cj 384, e n 640, b"\> 896, &c, the same as it would give 

 as a resonator, and that the pitch of these tones is so definite 

 that it is very difficult to alter any of them by the lips more 

 than two or three vibrations, except the lowest. We may here 

 note that the power of a resonator to reinforce the different 

 notes of a series of tones, with the prime or fundamental one 

 of which it is not truly in unison, is much greater for the fun- 

 damental than for the higher notes ; and this gives the reason 

 for the ease with which the fundamental note of a wind instru- 

 ment may be varied within pretty wide limits, say half a tone 

 sharper or flatter than its proper pitch. Taking, for illustra- 

 tion, a closed tube 21 inches long, it will be found to give ap- 

 preciable resonance to a fork of 128 vibrations with quarter 

 wave-length of 26^ inches, but scarcely any to a fork of 384 

 vibrations (g / the twelfth from c 128) with quarter wave-length 

 of 8| inches : when the c fork is sounding, the length of the 

 resonance-chamber is to the quarter wave-length as 21 to 26 J; 

 but when the g fork is used, the corresponding proportion is 

 practically as 3| to 8}; for in this case there is a second node 

 at a half wave-length, or 17 \ inches from the closed end. 



For musical purposes a cylindrical tube blown by the lips 

 is evidently unsuited, by reason of its poor tone, as well as by- 

 its giving only the odd intervals. The cone gives the required 

 intervals ; but it cannot be used by the lips in its complete 

 form ; it would be necessary to cut off a considerable portion 

 to get sufficient width for the action of the lips. Assuming 

 the cone shown on diagram to be cut at the second node of 

 note 4 (counting the node at the apex as the first) and there 

 closed by the lips, that note of the original cone can still be 



