1865.] Squire on the Quality of Musical Sounds. 601 



the higher tones of the uneven numbers — the third, fifth, and seventh 

 upper tones. The wide closed pipes are almost free from any upper 

 tones whatever, so that the quality will resemble that of the tuning- 

 fork. Sometimes a small tube open at both ends is inserted into the 

 cover of a closed pipe, and it is of such a length that its proper tone 

 corresponds to one of the upper tones (generally the fifth) of the 

 closed pipes, so that the sound acquires a peculiar clearness. The 

 absence of the upper tones of the even numbers gives the sound of 

 closed pipes a certain dullness in comparison with that of open ones, 

 but they form an excellent contrast to the shrillness of the latter. 



The sides of wooden pipes are not so well fitted as those of metal 

 ones to resist the vibrations of the air, and the higher tones are there- 

 fore quickly extinguished, so that the sound of these pipes is always 

 somewhat dull. 



In the so-called reed pipes the noise, to be purified and strengthened 

 by the pipe, is produced by the vibrations of a tongue of metal or 

 wood vibrating in a slit, which it closes or nearly so. When set in 

 motion by air blown through the slit, it admits at each vibration a 

 puff so as to produce a series of periodic impulses, which, acting on 

 the column of air in the pipes, sets it in a state of vibration. In the 

 organ and harmonium these reeds are of metal ; in the oboe and 

 clarinet, of wood. A similar arrangement may be produced by 

 the use of elastic membranes stretched across an opening, closing it 

 when at rest, but during the passage of a current of air they are forced 

 asunder, and again return to close it by their elasticity. This 

 arrangement occurs in practical music in two forms — in human lips 

 when blowing brass instruments, and in the larynx when singing. 

 The lips may be regarded as very slightly elastic membranous bodies, 

 heavily weighted with unelastic tissue, which by themselves would 

 vibrate very slowly, but used together as a means of producing a series 

 of puffs they are capable of producing a tolerably high tone. The 

 vocal chords are similar, but they have this great advantage over all 

 other reed instruments : that the opening of the slit, the tension, and 

 even the form, can be altered at will with great rapidity and precision. 

 In addition to this the form of the resonance tube, which is here 

 represented by the cavity of the mouth, can be changed so as to 

 produce a greater variety of sounds than any other instrument. The 

 metal reeds of the organ and harmonium are only intended to produce 

 a note of a certain fixed pitch. On these heavy and rigid reeds the 

 vibrating column of air in the pipe has but little reciprocating influence, 

 and such instruments must have a separate reed for every pipe. In 

 the wooden reed instrument there is but one reed, which must serve 

 for the whole series of notes. These reeds are made of a light, elastic 

 wood, and from their lightness they are themselves affected by the 

 vibrations of air they have set up !n the tube. They are capable not 

 only of giving the high notes corresponding to the periodicity of the 

 reeds, but also of exciting much lower notes when the tube is lengthened 

 by closing the holes. Under these circumstances the vibrations are 

 sufficiently powerful to carry the reed with them, and the pitch is 

 regulated by the length of the tube, and not by the oscillations of the 



