Of these rests, two, the semipausa and smpi- rium, have remained in use until the present day, and appear, slightly increased in size but of unchanged value, as the semibreve and minim rests. Two of the longer rests are also occasion- ally used in modern music, the pausa, or breve rest, to express a silence of two bars' duration, and the longa imperfecta a silence of four. These rests are called in French bdtons, and are spoken of as ' bdton a deux mesures,' ' a quatre mesures.'
The rests employed in modern music, with their names and values in corresponding notes, are shown in the table below. 1
By a license the semibreve rest is used to ex- press a silence of a full bar in any rhythm (hence the German name Taktpause) ; its value is therefore not invariable, as is the case with all the other rests, for it may be shorter than its corresponding note, as when used to express a bar of 2-4 or 6-8 time, or longer, as when it occurs (a) (&i (c) (d)
��In 3-2 time. To express a rest of longer duration than one bar, either the bdtons of two or four bars are employed (Ex. a), or, more commonly, a thick horizontal line is drawn in the stave, and the number of bars which have to be counted in silence is written above it (Ex. 6). (a) (6) 10
��Like the notes, the value of a rest can be in- creased by the addition of a dot, and to the same extent, thus --- is equal to --- p, [- * to p -] , and so on.
In the earlier forms of the ancient ' measured music ' rests were used as a part of the time- signature, and placed immediately after the clef. In this position they did not denote silence, but merely indicated the description of Mode to be counted. [See NOTATION, MODE, TIME, SIGNATURE.]
() (/) (*)
��ENGLISH. (a) Semibreve rest. (6) Minim rest. (e) Crotchet rest, (d) Quaver rest. () Semiquaver rest. (/) Demisemiquaver rest. (9) Semidemlsemiquaver rest.
(b) Demi-pause, (e) Soupir.
(d) Demi-souptr. () Quart-de-souplr. (/) Demi-quart-de-souplr. (g) Seizieme-de-soupir.
(b) Halbe Pause,
(c) Viertel pause, (ot) Achtelpause.
(a) Pausa della Semibreve.
(6) Pausa della Minima.
(e) Fausa della Semiminima, or Quarto.
(d) Pausa della Croma, or Mezzo Quarto.
(e) Pausa della Semicroma, or Kespiro. (/) Pausa della Biscroma.
(g) Pausa della Semibiscroma. [F.T.]
��RESULTANT TONES (Fr. Sons rfsultans', Ger. Combinationstone) are produced when any two loud and sustained musical sounds are heard at the same time. There are two kinds of re- sultant tones, the Differential and the Summa- tional. The Differential tone ' is so called be- cause its number of vibrations is equal to the difference between those of the generating sounds. The 'Summational tone' is so called because its number of vibrations is equal to the sum of those of the generating sounds. The following dia- gram shows the pitches of the differential tones of the principal consonant intervals when in per- fect tune.
�� ��Differentials. * * * fcj
If the interval be wider than an octave, as in the last two examples, the differential is inter- mediate between the sounds which produce it. These tones can be easily heard on the ordinary harmonium, and also on the organ. They are not so distinct on the piano, because the sounds of this instrument are not sustained. By prac-
i The German form of the crotchet rest differs from the English, being usually written thus j*. Rousseau also gives Italian forms of the semiquaver and demisemiquaver rests, thus T and T; these are howevei not common.
��tice, however, the resultant tones can be dis- tinguished on the piano also.
Dissonant as well as consonant intervals pro- duce resultant tones. Taking the minor Seventh in its three possible forms the differentials are as follows :
���The ist form of minor Seventh is obtained by tuning two Fifths upwards (C-G-D) and then a major Third downwards (D-/Bb) : its differential tone is /Ab, an exact major Third below C. The and form is gob by two exact Fourths upwards (C-F-Bb) : the differential is then \Ab, which is flatter than the previous /Ab by the interval 35 : 36. The 3rd form is the so-called Harmonic Seventh on C, whose differential is G, an exact Fourth below C. The marks \, /, here used to distinguish notes which are confused in the or dinary notation, will be found explained under TEMPERAMENT.
Hitherto we have spoken only of the differen- tial tones which are produced by the funda- mentals or prime partial tones of musical sounds. [See PARTIAL TONES.] But a differential may also arise from the combination of any upper partial of one sound with any partial of the other sound ; or from the combination of a differential with a partial, or with another differential.