The song of the week is the Bill Monroe bluegrass standard 'Mother's Only Sleeping' in E
Before reading the rest of this email, I recommend taking a listen or two to the attached mp3 file of the classic Bill Monroe/Lester Flatt recording of Mother's Only Sleeping. (Played in the Key of F on the recording.)
In the attached melody sheet, I have written the music in 6/4 time. 6/4 means that there are 6 beats per measure, and that each quarter note (like in 3/4 and 4/4 time) receives one beat.
Using dotted lines, I have divided each measure into two equal halves so that the music can be read in 3/4 time if desired.
The primary reason why I have written the music in 6/4 instead of 3/4 is because, unlike songs that are unambiguously in 3/4 (waltz) time (e.g., Amazing Grace, In The Pines, All The Good Times Are Past And Gone: guitar rhythm: BOOM-chuck-chuck, counted as 1,2,3 with the 'pulse' or 'feel' of the rhythm being 'strong-weak-weak'), Mother's Only Sleeping has more of a pulse of strong-weak-weak-medium-weak-weak. Guitar rhythm: BOOM-chuck-chuck-boom-chuck-chuck, counted as 1,2,3,4,5,6. That is, it takes 6 beats instead of 3 to complete one cycle of the rhythmic pattern.
Having said this, however, I think that playing in 6/4 (as opposed to 3/4) is best approached by simply 'feeling' the difference, instead of trying to think too much about it. For, it is such a subtle difference that most bluegrass players I know do not distinguish the two in theory, though they do distinguish the two in practise. (There are many excellent bluegrass players who have never heard of 6/4 time, let alone could explain how it differs from 3/4 time.)
The very fact that a song like Mother's Only Sleeping tends to be played at a faster tempo than songs like Amazing Grace, In The Pines, or All The Good Times Are Past And Gone, is usually enough to incline bluegrass guitar and bass players to play the second of every two consecutive 'booms' noticeably weaker than the first of those two consecutive 'booms'. This in turn naturally leads the rest of the instruments to also deemphasize the 4th beat of every 6 beat cycle. So, even though it may seem to you that in playing this song you are not doing anything all that different from how you would play songs like Amazing Grace and All The Good Times, you should notice that somehow it 'feels' a bit different, even if you can't quite put your finger on what that difference is. If, in playing the song, you feel the difference in its pulse, that is a good sign that, rhythmically, you are playing it correctly, and, therefore, you need not concern yourself with thinking about the difference between 3/4 and 6/4.
The progression (written in 6/4; one would need, therefore, to double the number of measures on each chord if one wished to rewrite the progression in 3/4) is:
In the key of E, 1=E; 5=B
The notes that make up the E chord are: EG#B
The notes that make up the B chord are: BD#F#
For the key of E, bluegrass guitar players will usually want to capo either to the 2nd or the 4th fret. (Playing in E without a capo is also a viable option. In this case, it would be customary to play a B7 chord on guitar instead of a B chord.)
If you capo to the 2nd fret, then the chord shapes will be the same as for the key of D: 1=D; 5=A. If you capo to the 4th fret, then the chord shapes will be the same as for the key of C: 1=C; 5=G. Those wishing to play a Carter-style break for this song will probably do better to choose the capo 4 option over the capo 2 option. Refer to the attached sheet music to tab conversion chart for 'Mother's Only Sleeping' in E.
I recommend that banjo players capo to the 2nd fret and spike/capo the 9th fret of the 5th string. (Playing 'D' shapes.) That way all the melody notes needed for a break can be found conveniently on the 4th, 3rd, and 2nd string, just like what is usually the case when playing in the key of G (most banjo players' favourite key). Refer to the sheet music to tab conversion chart attachment for help with locating the melody notes.
Since Mother's Only Sleeping has only two verses, and since the melody and chord progression of both halves of a full length break for this song are identical, in order to give every type of instrument a chance at playing a break (in addition to a collective break in which everyone who wishes to can play a break at the same time) without extending the break sections too long, I intend on splitting each of the breaks (except the collective break) between two different types of instruments. I also intend on kicking the song off with only half of a full-length break.