The rests for the fusa and semifusa were turned to the left in order to avoid the confusion that would ensue if the rest
stood for
. Besides, the sign would have easily become confused with the C clef
.
Signs for the changes of tempo, that is to say changes from quick to slow, etc., were introduced in the fifteenth century. The oldest of them consists of drawing a line through the tempus sign
. This meant that the notes were to be played or sung twice as rapidly as would usually be the case, without, however, affecting the relative value of the notes to one another. Now we remember that the sign