600 Original Articles. [Oct., 



unsupported on the upper wooden surface, and this conveys to it the 

 vibrations of the strings, which are again transmitted to the air by 

 the greater surface of the wood. But a hollow space enclosed by 

 elastic walls like those of the violin must have certain proper tones 

 which may be evoked by blowing into the openings. Savart found 

 this to be for the violin c' and for the violoncello F. This will 

 have the effect of strengthening those tones which approximate to 

 those of the hollow space, and it is found both in the violin and vio- 

 loncello that these tones come broadly out. As the lowest note of 

 a violin is g, it is only the upper tones of the three lowest notes 

 which will be increased by resonance, while of the other notes 

 generally, the fundamental will be augmented rather than the upper 

 tones, as they approximate more to the peculiar tone of the body 

 of the instrument. 



The pipes of an organ consist of two parts, a sharp edge against 

 which a current of air is driven, and a hollow pipe which may be 

 either closed or open at the top. These pipes act in a similar way to 

 the resonators of Helmholtz. The air when driven against the sharp 

 edge, produces a kind of whistling hissing noise, which consists of 

 unharmonic tones lying tolerably close together. The pipe itself 

 is capable of strengthing, by its resonance, just those tones and those 

 only which are either its fundamental or its harmonic upper tones. 

 All other sounds remain unaffected, and are almost completely 

 masked by the increased power of those fortified by the pipe. By 

 blowing very hard the pitch of the noise is raised and the funda- 

 mental may disappear, and only the upper tones remain. A flute is 

 in precisely the same predicament as an organ pipe — certain tones 

 produced in the noise made by blowing across the holes are strengthened 

 by the tube, which may be made shorter or longer by closing the 

 holes. A flute, when gently blown with all the holes closed, gives 

 d', by stronger blowing d", by still stronger a", or even d'" — the 

 series of harmonic upper tones of d'. In those parts of the organ 

 consisting of narrow cylindrical pipes the fundamentals are accom- 

 panied by very clear powerful upper tones, which produce that sharp 

 fiddle-like character of the Viola di Gamba and other stops ; by the 

 help of the resonators the sixth upper tone may be clearly distin- 

 guished, a tone which is also very powerful in the fiddles themselves. 

 In the wide pipes there is far less tendency to fortify the higher upper 

 tones, so that these pipes will bear much harder blowing than the 

 narrow ones without starting into upper tones, and on this account, 

 and because the vibrating mass of air is large, they are used to produce 

 the chief volume of sound, and are called principals. In the wooden 

 principals the second tone (the octave) is easily recognized, the third 

 (the higher fifth) is weak, and the still higher ones are no longer 

 audible. In the metallic principals they are found as high as the 

 fourth tone. The quality of tone in these pipes is fuller and softer 

 and less shrill than in the narrow ones (violin principals). By 

 narrowing the upper end of the tubes the fifth and seventh tones 

 become more prominent, and the sound is on this account thin, but 

 clear and brilliant. The narrow closed pipes are characterized by 



