1865.] 



Squire on the Quality of Musical Sounds. 



595 



Still they had been observed long ago, particularly in the violin and 

 violoncello, but were regarded as curious facts without any suspicion 

 of their real importance. To distinguish them accurately and 

 determine their intensity and pitch, requires an artificial help, which 

 is supplied by the resonators of Helmholtz. These consist of glass 

 globes, or very wide tubes, with an opening at each end, as in Fig. 7. 



Fig. 7. 





The smaller opening is made to fit accurately into the ear by 

 means of a covering of sealing-wax, which is pressed while still warm 

 into the opening of the ear, so as to take its exact form. Instru- 

 ments of tins kind possess the property of resounding and intensify- 

 ing those sounds, and those sounds only, which are called forth 

 by blowing across the wide opening. They are made of various 

 sizes, each corresponding to a particular note in the scale. When 

 one of these instruments is applied to the ear, and the other ear is 

 perfectly closed, scarcely anything is heard of the external sounds, 

 unless a sound be present of precisely that pitch which corresponds 

 to the resonance of the globe when it bursts at once loudly on the 

 ear. By means of this contrivance a complete analysis can be made 

 of a mixed sound, resolving it into its fundamental and attendant train 

 of upper tones. 



It is to these secondary tones that we must ascribe what is called the 

 peculiar equality of the sound. As they are present in greater or less 

 proportion, so the sound is fuller or duller, just as a single note struck 

 on a pianoforte is thin and poor, but is rich when supplemented byits 

 chord, so the simple fundamental note is modified by the upper tones 

 by which it is accompanied. Indeed the first six harmonic upper 



