71. Sometimes an accidental occurs with the turn, and in this case when written above the sign it refers to the highest tone of the turn, but when written below, to the lowest (Fig. 48).
72. In the _inverted turn_ the order of tones is reversed, the lowest one coming first, the principal tone next, the highest tone third, and the principal tone again, last.
73. The _appoggiatura_ (lit. _leaning note_) consists of an ornamental tone introduced before a tone of a melody, thus delaying the melody tone until the ornamental tone has been heard. The time taken for this ornamental tone is taken from that of the melody tone.
The appoggiatura was formerly classified into _long appoggiatura_ and _short appoggiatura_, but modern writers seem to consider the term "short appoggiatura" to be synonymous with acciaccatura[12], and to avoid confusion the word _acciaccatura_ will be used in this sense, and defined under its own heading.
[Footnote 12: In organ music the acciaccatura is still taken to mean that the embellishing tone and the melody tone are to be sounded together, the former being then instantly released, while the latter is held to its full time-value.]
74. Three rules for the interpretation of the appoggiatura are commonly cited, viz.:
(1) When it is possible to divide the principal tone into halves, then the appoggiatura receives one-half the value of the printed note. (Fig. 50.)
(2) When the principal note is dotted (division into halves being therefore not possible), the appoggiatura receives two-thirds of the value. (Fig. 51.)
(3) When the principal note is tied to a note of smaller denomination the appoggiatura receives the value of the first of the two notes. (Fig. 52.)
75. The _acciaccatura_ (or short appoggiatura) is written like the appoggiatura except that it has a light stroke across its stem. [Illustration] It has no definite duration-value, but is sounded as quickly as possible, taking its time from that of the principal tone. The appoggiatura is always accented, but the acciaccatura never is, the stress always falling on the melody tone. (See Grove, op. cit. Vol. I, p. 96.)
The use of embellishments is on the wane, and the student of to-day needs the above information only to aid him in the interpretation of music written in previous centuries. In the early days of instrumental music it was necessary to introduce graces of all sorts because the instruments in use were not capable of sustaining tone for any length of time; but with the advent of the modern piano with its comparatively great sustaining power, and also with the advent in vocal music of a new style of singing (German Lieder singing as contrasted with Italian coloratura singing), ornamental tones were used less and less, and when found now are usually written out in full in the score instead of being indicated by signs.