It realised that the various species of bagpipe chanters could be plotted on a graph
ideal stability ____________________________________________ideal instability
the two “ideal” spots giving chanters with opposite advantages.
I’m calling “ideal stability” a chanter that’s totally fingering-blind: as long as you’re lifting the finger that covers the hole from which a note emits, that note will be in tune and clear regardless of what the fingers lower down the chanter are doing.
What’s “ideal” about it? For one thing you can finger fast complex passages using the most efficient fingering, Economy Of Motion, fingerings that allow maximum clarity of note-changes with minimum finger motions.
Most piping traditions have quite a bit of Economy Of Motion already built into their fingering systems by using partially-closed fingerings for many notes.
And I’m calling “ideal instability” chanters which, due to the large range of pitches which can emit from a single note-hole depending on what the fingers further down the chanter are doing, allow a full chromatic in-tune scale to be played on a keyless chanter, in many cases including playing in-tune 2nd octave notes.
An example of very stable chanters are narrow-bore things like Northumberland smallpipes and Scottish practice chanters and smallpipes, and Bulgarian gaidi.
The first time I saw somebody playing gaida I studied the gaidar’s fingers but couldn’t make much sense of the fingerings. When he took a break I asked him “what are the fingerings?”.
He answered “anything”. And sure enough after I got a gaida and spent several years playing it I found out it was true, pretty much. As long as you opened the uppermost hole for a given note the fingers further down could be up or down in any combination. (This of course doesn’t include the action of the mormorka.)
And as a Highland piper, when I spent months playing only Scottish smallpipes when I returned to the Highland pipes I discovered that some alternative fingerings had crept in, ones which made no difference on the Smallpipes but did on the big pipes.
Chanters with “ideal instability”, in other words have enough instability to respond flawlessly to alternate fingerings to play chromatically and reach up into the 2nd octave, include the Gaita Galega, Central French pipes, and Low Countries pipes. The Scottish so-called Border pipes can indeed play chromatically but the ones I’ve had weren’t good at going into the 2nd octave.
Then there’s the middle ground, where chanters might give one or two chromatic notes but not a full chromatic scale, like the Highland pipes and uilleann pipes, while at the same time many of the other notes of the scale are out of tune unless you use a specific fingering.