"palindromic" is slightly more general.  For example, Grandsire is palindromic, but the symmetry points aren't when the treble is leading full or at the back, but one blow afterwards, when the treble and the hunt bell trade places.

I found John's notes to be extremely helpful when studying Bristol.

 David


On Tue, Jun 22, 2021 at 7:33 AM John Danaher <jsd@alum.mit.edu> wrote:
When I was ringing in New York, we were spending a lot of time on
Bristol on various stages.

I've attached a couple printouts I put together at the time. One that shows
a set of "rules" for how the place notation makes bells behave in different
parts of the row in Bristol Major through Max. The other demonstrates (on
the second page) how the double symmetry fits together.

 - John

On Mon, Jun 21, 2021 at 11:35 PM Elaine Hansen <EHansen@minlib.net> wrote:

> I quibble.
> (perhaps erroneously)
>
> Palindromic means that the place notation to dodge the treble, say, in 3-4
> up is the same as the place notation
> to dodge the treble 3-4 down.
> There will be a pivot bell, it will make the place at the half-lead, and be
> symmetric about the half-lead.
> Cambridge is palindromic.
> Plain bob is palindromic.
>
> Bristol has a stronger form of symmetry.
> It's a double method.
> So the place-notation to dodge the treble 1-2 up (5ths, in this case) is
> the mirror of the place notation
> to dodge the treble 7-8 up.  (4ths).
> (And as you correctly say, if you flip the line in the mirror and translate
> it a half a course, you get
> the same line.  So point 4ths lead point 4ths for seconds place bell around
> the halflead, or
> point 5ths lie point 5ths for the end of 7ths place bell, lead end,
> beginning of 8ths place bell)
>
> [Superlative is also double.]
>
> On Mon, Jun 21, 2021 at 7:45 PM Joshua Burson <joshburson09@gmail.com>
> wrote:
>
> > Hi all,
> > In the wake of yesterday's successful QP, I had another look at Bristol,
> > trying to understand it via my traditional method of turning it into a
> sort
> > of mostly-rule-based Methodoku.  Sending this out to non-Bristol ringers,
> > on the off-chance case that people are interested:
> > -  This is a palindromic Surprise method *(i.e.: the treble treble-bobs,
> > and if you just drew the lines on a piece of paper, leaving out the
> > numbers, they would form a mirror image across the half-lead, when the
> > treble's lying behind; see also
> > http://jaharrison.me.uk/Ringing/Glossary/P.html
> > <http://jaharrison.me.uk/Ringing/Glossary/P.html>.)*
> > - There are no long places (i.e., you never strike more than two blows in
> > the same position in a row.)
> > - The #6 starts by making a Stedman whole turn in 5-6, then makes a fish
> > tail *(7th, 8th, 7th, 8th, 7th) *in 7-8.  They then dodge in 5-6, run
> > in,make a point lead, make places in 4-5, run out, make a point at the
> > back, and run back in.
> > At the start of the NEXT lead, they're going to dodge in 3-4 and then do
> a
> > fishtail in 1-2.
> > -------------- next part --------------
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