The C clef is on that line which has an oblique or straight stroke, or pot-hook, above and below.
The F clef is on that line which its interior termination is on, and which it curls round either to the right or the left, and which has a dot above and below.
And this position never varies. Whatever line the F clef is on is F, however many or few lines may be above or below it.
In olden days any clef line might be taken with any number of lines above and below. For instance, the F line with two lines below and two above; or three below and one above. This is not now done with treble and bass clefs, which are only used with respectively the top and bottom five lines of the Great Stave of eleven lines. Hence care must be taken to write the treble clef on the _second_, and the bass clef on the _fourth_ line of its stave. But it is still customary to use the C clef, especially in viola and trombone music, with both two lines above and two below, making the alto stave; and three below and one above, making the tenor stave. These staves are also used in old vocal music, and familiarity with them is absolutely necessary in all advanced theoretical examinations. The C clef, therefore, _appears_ to move, being sometimes on the third and sometimes on the fourth line. Really it is always on the same line, and it is the _selection of lines_ which varies. Hence the misdescription of the treble and bass clefs as "immovable," the C clef as "movable."
Note that all clefs are on lines; no clef is in a space. This is because the first attempt to accurately represent music to the eye was by means of a single line with a letter at the beginning. This was what has since become the fourth line, the clef line, of the bass stave.
In pianoforte and organ music, high parts for the left hand, or low ones for the right, may be written either:
By writing the part in the stave proper to the other hand (c).
The example, of course, illustrates a high part for the left hand.
The first method is the hardest to write and read. There is not much to choose between the second and third. If the third be adopted care must be taken not to insert rests in the vacant stave: their absence shows that the _hand_ is not resting.
