Andersen. — New Zealand Bird-song. 521 



principal note, their rates of vibration being double that of the full string ; 

 where the division is into three, the vibrating parts give a sound a twelfth 

 above the principal note, or a fifth above the first octave ; where the divi- 

 sion is into four, the vibrating portions give a sound two octaves above the 

 principal note, as their rates of vibration are four times that of the full 

 string ; where it is into five, a sound a seventeenth above the principal 

 note, or a third above the second octave ; and so on. The full note is, in 

 fact, composed of quite a number of different sounds, called harmonics or 

 partial tones. Whilst they are present they are exceedingly faint, the 

 smaller the subdivision producing them being the fainter being the sound 

 emitted, and the less distinguishable from the much fuller body of the 

 principal note. The ordinary unaided ear is able to detect the first four 

 or five partial tones only ; yet the presence or absence of these and the 

 higher partials determines the richness and quality of the resultant sound. 

 The vibration of different materials produces different partials, or produces 

 them in different degrees of intensity : the human voice is rich in the lower 

 partials ; in cymbals and like " noisy " instruments the upper partials 

 predominate. The nasal quality of the oboe and clarionet is caused by 

 the absence of the even partials- — the second, fourth, sixth — and the 

 presence of the odd — the first, third, fifth, seventh. 



The harmonics or partial tones of the open G string of the violoncello 

 are represented in the subjoined diagram : — * 



The first partial tone is the principal note ; the second is produced by the 

 string dividing into two parts ; the third by its dividing into three ; and 

 so on to the thirteenth partial here shown. 



It seems hardly credible that such a number of notes should all be 

 sounding when the G string is set in motion, yet the fact is, by mechanical 

 means, quite demonstrable. It is easy for the ordinary unassisted ear to 

 detect at least the lower partials. If the G be struck on the piano, and 

 the sound be allowed to die away by keeping the damper from the wire, 

 as the principal note becomes fainter the third and fifth partials, D and B, 

 are heard, faintly but clearly. The second and fourth partials, being the 

 first and second octaves of the principal note, whilst heard as clearly as 

 the third and fifth, are not so readily distinguished, as they do not differ 

 in actual sound, but in pitch only. They may be heard in this way : Hold 

 down the key of the principal note, G, without striking the wire ; then 

 strike the G above it- — the second partial- — and after a second or two release 

 the key, still holding down the lower G. The sound of the G struck, and of 

 the G an octave above it- — the second and fourth partials- — will now be 



* From Momigny, Grove's Dictionary of Music, Harmonics. 



