Bar-lines are usually drawn through each stave of vocal music separately, and in instrumental music through as many staves as belong to the same instrument or group of instruments, _e.g._, through the two staves of a piano part, and the four or five belonging to the "strings" in a full score. These instrumental staves are also usually connected by a brace at the left-hand edge of each score thus:
Uniform bar-lines may be ruled a page at a time, if care be taken not to make the line continuous through more than the required number of staves. It is a fault which one commits the moment watchfulness is relaxed, and entails much scratching out. Where the measures vary in length the ruling will most readily be done in light pencil with a T square, and afterwards inked. A single bar-line out of the perpendicular will spoil the appearance of a whole page.
5.--The first actual musical characters to be written are the clefs. Misconception of the function of these is so common, not among practical musicians only, but on the part of elementary theorists, that a few words of explanation are necessary. The commonest fallacies are to suppose that if clefs are the right shape their exact position on the stave does not matter, and that their position varies. Both suppositions are, to quote a delightful Ruskinism, "accurately false." A clef identifies and originally was used with _a single line_, and identifies others only by their relationship to this. Hence its precise shape is of less importance than its being on the right line. Indeed, the shape of clefs has varied so much that many able practical musicians do not know that they were originally simple letters, the treble clef a small "g," the bass clef a small "f." From this beginning has been evolved so elaborate a sign, sometimes not merely covering all the lines of a stave, but going beyond them, that it is necessary to explain which line a clef is on. Thus the "G," or treble clef, is on that line which its interior termination is on, and which it curls round, touching it in all _four times_. The upper part of the treble clef is sometimes kept within the stave, but, as in the present examples, more often rises above the stave. The point is merely a matter of taste.