I was trying to add this to my earlier post, but ran out of editing time....
The usage referred to by Steve citing Blair is different: it references a swung rhythm, based on a triplet pattern.
1&2& would always be four half-beats, but the addition of an
a in
1&
a2 changes
every duration value, for now, the numbered beat
1, the
& and the
a are all one-third beats. The 1& are blended into one sound or duration (or the & is silent - we can't tell) and the a stands as a syncopated off-beat, the durations being 2/3 1/3 1. I have never encounted the
& symbol being used in this ambiguous way before. I understand it to operate to divide into two equal parts the numbered beat preceding the symbol. In the same way,
e or
a (or eh and ah) divide the preceding half-beat (
&) into two quarters. So, to take the comparison made earlier, a swung triplet rhythm (given as
1&
a2), isn't the same as the not-swung rhythm of the International Jive Chasse
1e&
a2, although the convention is not to give the symbols for silent or blended sub-counts, so actually written as
1a2 (3/4 1/4 1).
Tangomonkey
linked to an explanatory text that addressed the swung rhythm variant, but there, the
& symbol is not used, but the word
and is given instead:
1 and ah 2 - that makes sense to me, and solves the problem of
& meaning different things depending on context. The difference doesn't survive
saying the pattern, but that is also true of Robert Farris Thompson's citation of
da, ka ka kan, for the habanera rhythm, where the italics are necessary to attribute different durations to the two
ka sounds. A different sound would have been better, and what is the comma after
da meant to signify? Musical notation, for those that can read it, is indeed, rather easier to comprehend, but all of these alternative counting systems are meant to be usable verbally, and by anyone. Some standardisation, therefore, in usage, across dance genres, would be helpful. Most teachers resort to
double-time, and leave it at that, although in relation to the habanera variants, that is about as useful as a chocolate teapot.