48. For the sake of definiteness in referring to pitches, a particular name is applied to each octave, and all pitches in the octave are referred to by means of a uniform nomenclature. The following figure will make this system clear:
Thus e.g., "great G" (written simply G), is the G represented by the first line of the bass staff. Small A (written a), is represented by the fifth line of the bass staff. Two-lined G, (written
), is represented by the space above the fifth line, treble staff. Three-lined C, (written
), is represented by the second added line above the treble staff, etc. The one-lined octave may be described as the octave from middle C to the B represented by the third line of the treble staff, and any tone within that octave is referred to as "one-lined." Thus—one-lined D, one-lined G, etc.
In scientific works on acoustics, etc., the pitches in the sub octave (or sub-contra octave as it is often called) are referred to as C2, D2, E2, etc.; those in the contra octave as C1, D1, etc.; in the great octave, as c1, d1, etc.; in the small octave as c2, d2, etc.