Nearly allied to the subject of pitch, is that of intervals; and the explanation of them carries our argument a step further.  While calm speech is comparatively monotonous, emotion makes use of fifths, octaves, and even wider intervals.  Listen to any one narrating or repeating something in which he has no interest, and his voice will not wander more than two or three notes above or below his medium note, and that by small steps; but when he comes to some exciting event he will be heard not only to use the higher and lower notes of his register, but to go from one to the other by larger leaps.  Being unable in print to imitate these traits of feeling, we feel some difficulty in fully realising them to the reader.  But we may suggest a few remembrances which will perhaps call to mind a sufficiency of others.  If two men living in the same place, and frequently seeing one another, meet, say at a public assembly, any phrase with which one may be heard to accost the other—­as “Hallo, are you here?”—­will have an ordinary intonation.  But if one of them, after long absence, has unexpectedly returned, the expression of surprise with which his friend may greet him—­“Hallo! how came you here?”—­will be uttered in much more strongly contrasted tones.  The two syllables of the word “Hallo” will be, the one much higher and the other much lower than before; and the rest of the sentence will similarly ascend and descend by longer steps.

Again, if, supposing her to be in an adjoining room, the mistress of the house calls “Mary,” the two syllables of the name will be spoken in an ascending interval of a third.  If Mary does not reply, the call will be repeated probably in a descending fifth; implying the slightest shade of annoyance at Mary’s inattention.  Should Mary still make no answer, the increasing annoyance will show itself by the use of a descending octave on the next repetition of the call.  And supposing the silence to continue, the lady, if not of a very even temper, will show her irritation at Mary’s seemingly intentional negligence by finally calling her in tones still more widely contrasted—­the first syllable being higher and the last lower than before.

Now, these and analogous facts, which the reader will readily accumulate, clearly conform to the law laid down.  For to make large intervals requires more muscular action than to make small ones.  But not only is the extent of vocal intervals thus explicable as due to the relation between nervous and muscular excitement, but also in some degree their direction, as ascending or descending.  The middle notes being those which demand no appreciable effort of muscular adjustment; and the effort becoming greater as we either ascend or descend; it follows that a departure from the middle notes in either direction will mark increasing emotion; while a return towards the middle notes will mark decreasing emotion.  Hence it happens that an enthusiastic person uttering such