This is a musical term. It is not another version of the song
'ninety nine bottle of beer on the wall', or anything close. I'm
trying to figure out how we ended up with this concept.
The concept is rather simple. It's an ordered set of notes, both
ascending and descending from a C. To get the next note in the
ascending direction, you go up a perfect fifth. To get the next
note in a descending direction, you go down a perfect fifth. The
pattern looks like this:
G-flat, D-flat, A-flat, E-flat, B-flat, F, C, G, D, A, E, B, F#
Two notes are enharmonically the same when they are on the same pitch,
but 'spelled' differently. Note that in the circle of fifths
shown here, the F# and G-flat are the same, enharmonically
speaking. So the circle of fifths will wrap back on itself, like
a circular clock, enharmonically.
However, if you continue the pattern upwards, you get into fancier
spellings for the same thing....
and if you press the point, I suppose these notes do theoretically
exist and I have seen some of them in written music over the
years. But they are enharmonically equivalent to simpler forms of
the same notes.
At any rate, the basic series is:
F, C, G, D, A, E, B
But, why on earth is it useful to put notes in order, spaced a
perfect fifth apart?
One reason is that it helps you figure out what key some music is
written in. You count the number of sharps or flats and find that
position in the circle of fifths, and that tells you the key the music
is written in. This rule varies between major keys and minor keys
though, as follows.
For Major Keys......
Flats 7 6
5
4 3
2 1
0 1 2 3
4 5 6
7 Sharps
C-flat, G-flat,
D-flat, A-flat, E-flat, B-flat, F,
C, G, D, A, E, B,
F#, C#
For Minor Keys......
Flats 7 6
5
4 3 2 1
0 1 2 3 4
5 6 7 Sharps
a-flat e-flat
b-flat f c
g d a
e b f# c# g#
d# a#
I have been trying to explain why the number of sharps required
increases by one when you move from one key up a perfect fifth to
another key, andwhy the number of flats required increases when you
move from one key down a perfect fifth to another key.
First, assume we had no sharps and flats. Based on the
description of note spacing in the major, minor, and church modes (see
Diatonic scales under Music Theory section, this web site) we
could play each type of scale only in one key, as follows:
Major
C
Dorian
D
Phrygian
E
Lydian
F
Mixolydian
G
Minor
A
unknown
B
The interval spacing pattern of the 'natural' notes is as follows:
Two major seconds, then a minor second, then three major seconds, then
a minor second.
If you want to add just one note to the set of seven (a sharp or a
flat) you need to know where in the pattern to insert one
additional note so you will be able to have the same pattern but
starting on a different note. So, you try sliding the pattern
up-pitch and down-pitch until you find a point where there is only one
more note required to form the same interval spacings of
M2, M2, m2, M2, M2, M2, m2.
And for some reason, that is consistantly a perfect fifth up or down
from the previous point.
So far, so good. But, then why when we slide the pattern up to
begin on a G and see the need for another note between F and G, why
call it F# instead of G-flat? The only reason I can think of is
that we don't need the F in the new pattern, but we do need the G, so
we might as well call the new note by an unused letter name plus the
modifier.
I hope this helps somewhat to understand the circle of fifths.
Somehow it doesn't give me a very warm fuzzy.
So, to round out this discussion, when you see some music with a
certain number of sharps or flats in it, refmember the little chart
from above, repeated here.....and look up the number of sharps or flats
and that tells you what key the song is most likely in. Remember
to use the right chart though, because major is different than minor.
Or, if you are playing a song by ear and want to know what key it is
in, observe the notes you are using.... you need all seven within an
octave.... and count the number of sharps or flats, then refer to these
charts to see what key you are most likely playing in.
For Major Keys......
Flats 7 6
5
4 3
2 1
0 1 2 3
4 5 6
7 Sharps
C-flat, G-flat,
D-flat, A-flat, E-flat, B-flat, F,
C, G, D, A, E, B,
F#, C#
For Minor Keys......
Flats 7 6
5
4 3 2 1
0 1 2 3 4
5 6 7 Sharps
a-flat e-flat
b-flat f c
g d a
e b f# c# g#
d# a#
Now that you're familiar with the circle of fifths the next step
is to choose a key and determine the seven notes it should contain.