[r-t] Re: apologies

[Richard Smith]

Ben Willetts wrote:

> I can see three possible extension routes [for Duffield Major]:
>
> 1.  --> x36x-10 --> x36x-1T.  This is what has been rung and named, but as
> the extensions are no longer double, would this extension still be valid?

No.  As the extension doesn't have the same symmetry as the
parent, it is not valid.  See (G)B.2.

> 2.  --> x38x-10 --> x30x-1T.  The Royal method turns into a differential (as
> would 16, 22, 28, ...) but the Maximus works.

This is the correct extension of Duffield.  It works on any
even stage, n, except when n = 4 (mod 6).

> 3.  --> x38x38x-10 --> x30x30x30x-1T.  Presumably the problem here is that
> the division length changes, although it is still recognisably a derived
> method.

No.  Extension of principles must preserve the lead length.
See (G)D.1(a).

RAS