[r-t] Symmetry, bluelines and differentials

[Ben Willetts]

On 21/02/07, Don Morrison <dfm at ringing.org> wrote:
> For normal methods, possessing the usual symmetry about a half-lead in
> the changes results in the blueline for all the working bells also
> possessing a similar symmetry.
>
> But in differentials this isn't quite the case. For example, consider
> the differential formed by having cross instead of places at the lead
> end and half lead of London Major:

Having the cross change, instead of places being made, removes the
'pivot point' and means that (a) one lead can't be its own reverse,
and (b) consecutive leads can't be reverses.  This presumably has
something to do with it.

Ben