You are, I take it, by now thoroughly versed in the principles of rhythm which have been explained to you over the last two articles with laborious exactitude. In addition, I trust that you've earnestly continued to swot over the 2nd issue, which explained with dogged patience the names of the notes and their secret hiding-places on your instruments. By keeping a clear head, it should be possible for you to combine these two elements which I have generously taken the time and trouble to outline, and produce TUNES and MELODIES from you wretched banjos and accordions. I don't have to do this, you know. I could have been a nuclear physicist...
When you see a melody written down, the first symbol given is the clef.
is the treble clef [top],
the bass clef [bottom].
The next indication is the 'key signature' (if any). This tells you what sharps or flats are going to occur throughout the piece, which in turn tells you what key the piece is in. For example:

This example, a sharp sign on the F line, means that all Fs in the piece will be sharp unless contra-indicated by a 'natural' sign. A natural,

written in front of a note in the same way as a sharp or flat sign (b) cancels any previous instructions and makes the note its 'natural' self.
Another common key signature is

meaning that all Bs will be flat throughout the piece. Incidentally, the 'accidental' sign (ie sharp or flat) used in a key signature applies to the named note in
any position on the stave — so

are all B flats!
The reason for using a key signature is that it saves having to write in the accidental each time it occurs. The only problem for the reader is then to
remember that all Fs are sharp, all Bs and Es are flat, or whatever. However, this soon becomes second nature when the accidentals of each key are learnt.

signifies the key of G major. This has only one accidental, the F#. Try playing the eight notes of the G major scale on your Sootyphone, banjo, or Oberheim 8-voice polyphonic synthesiser:

Got it? These two accidentals:

signify the key of D major, the scale of which is:

A piece with no key signature indicated means one of two things; either it's in the key of C major, with no accidentals whatsoever-

or else it's the sort of piece where the key changes quite a lot, and the writer prefers to write in the accidentals as they occur. Here is a table of most of the major keys and the scales thereof:

Notice that in the keys of F#, C# and G# major some esoteric notes like E# , B# and Cb occur. Remember that E# = F, B# = C, and Cb = B! The reason for adopting what might seem a rather unnecessary accidental is to preserve the
visual shape of the written scale.

is a far less satisfactory way of writing the scale of F# major than

because the 'shape' of the former is wrong. In order to satisfy the eye, a major scale when written down should look like

To achieve this smooth ascent, the note name has to change at each of the seven steps of the scale. Two Fs (one an Fnatural , the other an F#) at the end of the first example of the F# major scale gives a false sense of 'sameness' to the two notes and spoils the shape of the rising scale: E# and F# (although of course sounding exactly the same as Fnatural and F# ) are more obviously different notes... Think about it!
You may have noticed that there are some possible major scales, for example G# major and D# major, which are omitted from your table. The reason for this is a new terror which so far I've been reluctant to reveal to you, but now I fear there is no alternative. In order to preserve the correct shape of some major scales (and adhere to the principle of the note name having to change at each step of the scale) it is sometimes necessary to use 'double flats' and 'double sharps'. A double flat (written bb) lowers the pitch of a note by a
whole tone (groan). In other words, Abb = G (shriek). A double sharp (written x) raises the pitch of a note by a whole tone (howl). Gx = A (sob).
I'm really sorry about this. Many of you may by now have turned to other pages of the magazine (Hmm, what's this? Looks interesting -
Your Synth and Why Not to Drop It by Dave Crombie) or have thrown it into a far corner of the room in a vain attempt to banish from your minds this new piece of insufferable academicism. However, it does make sense. If you try to write the scale of D# major without using double sharps, the result is:

With double sharps, it looks like this:

- notice how the note name changes at each step of the scale in the latter instance.
There are also examples of where double flats can be similarly usefully employed, but let's leave that for now. They aren't common enough to warrant too much anxiety at this stage.
Some notes on key signatures and that sort of thing; where a natural sign is used to cancel an accidental indicated by a key signature (for example,

the natural sign is only effective for the duration of the bar in which it occurs. After this bar, the key signature accidentals come into force again. If (in the previous example) an Fnatural were needed in the second bar as well as the first, it would have to be written in again.

This also applies to extra accidentals. If the key signature were

(ie key of D major) and a G# was needed in one bar -

the sharp sign would only affect Gs in
that bar. The same is true of flats, double flats and double sharps.
A whole key signature can be 'cancelled' by utilising the appropriate natural signs.

Note how, in the last example, the F# is cancelled, then re-introduced as an accidental in the new key.
In a key signature, sharps and flats are never intermingled, but kept apart in a sort of enharmonic apartheid. If you wanted to write a melody out in the key of D major, it would be wrong (or at least, misleading) to write

as an indication of the key signature.

is much better!
If you like you can practice playing the various major scales written earlier. Try to get the idea of which accidentals apply to each key - I'll be back in a month with more scandalous musical tit-bits... Ta-ra for now.