intermits so frequently that its separate existence cannot be
perceived. It is only in the want of continuity of such vibrations, and
in their want of harmony inter se, that a noise differs from a musical
note. Thus an ear to be capable of discriminating noises and the high
importance of this power to all animals is admitted by every one must
be sensitive to musical notes. We have evidence of this capacity even
low down in the animal scale: thus Crustaceans are provided with
auditory hairs of different lengths, which have been seen to vibrate
when the proper musical notes are struck. (32. Helmholtz, Theorie
Phys. de la Musique, 1868, p. 187.) As stated in a previous chapter,
similar observations have been made on the hairs of the antennae of
gnats. It has been positively asserted by good observers that spiders
are attracted by music. It is also well known that some dogs howl when
hearing particular tones. (33. Several accounts have been published to
this effect. Mr. Peach writes to me that an old dog of his howls when B
flat is sounded on the flute, and to no other note. I may add another
instance of a dog always whining, when one note on a concertina, which
was out of tune, was played.) Seals apparently appreciate music, and
their fondness for it was well known to the ancients, and is often
taken advantage of by the hunters at the present day. (34. Mr. R.
Brown, in Proc. Zool. Soc. 1868, p. 410.)
Therefore, as far as the mere perception of musical notes is concerned,
there seems no special difficulty in the case of man or of any other
animal. Helmholtz has explained on physiological principles why
concords are agreeable, and discords disagreeable to the human ear; but
we are little concerned with these, as music in harmony is a late
invention. We are more concerned with melody, and here again, according
to Helmholtz, it is intelligible why the notes of our musical scale are
used. The ear analyses all sounds into their component simple
vibrations, although we are not conscious of this analysis. In a
musical note the lowest in pitch of these is generally predominant, and
the others which are less marked are the octave, the twelfth, the
second octave, etc., all harmonies of the fundamental predominant note;
any two notes of our scale have many of these harmonic over-tones in
common. It seems pretty clear then, that if an animal always wished to
sing precisely the same song, he would guide himself by sounding those
notes in succession, which possess many over-tones in common that is,
he would choose for his song, notes which belong to our musical scale.
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