robin at robinw.org.uk
Sat May 2 08:03:06 UTC 2015
Don's comments in the first post of Issue 2 reminds me that, in the
original version, what was entitled 'pivot bell sequences' were
preserved. This just is another way of saying place-bell order was
preserved. This would immediately rule out Bristol S Max (but not the
Royal), since BS8 is gp MX but BS12 is gp J.
In simple terms, if you ring a gp A parent, in which place bells (from
2nds) increase to a peak and then return to 2nds, you *might* 'produce a
method acceptable to the practical ringer (not so much the
mathematician) as the obvious extended form of the parent' rather than
an extension in gp B, say, where there are two 'peaks'.
Plot a graph of place-bell against lead-number and you will see what I
mean. Gp C has three peaks, etc; gps F, G and M 'look' like gp A, etc.
The 1952 report says " if the structure of a lead of an extension be
satisfactory, the “likeness” of the blue-line of the extension to that
of the parent will be governed by the order in which the leads are
joined together" and a table gave the instruction that, in effect, group
letter must be preserved by selecting the appropriate pivot-bell sequence.
More information about the ringing-theory