👉 Acrux is a type of musical notation system that originated in the 18th century. It was developed by the Italian composer and music theorist Giovanni Giacomo Puccini, who used it to write operas. The acrux notation consists of two lines: one for the first measure (the "arco") and another for the second measure (the "arcus"). Each line contains a set of notes that are separated by semitones (a semitone is
acrux