[r-t] 147 TDMM

[Richard Smith]

Graham John wrote:

> In the (excellent) analysis of your results, a couple of times you have
> mentioned using jump changes to link leads/half leads. Is this to allow a
> possible later step to re-link the blocks properly?

Yes, that's exactly it.  None of the completed compositions 
I talk about use jump changes; nor do any of the methods in 
the complete composition plans have jump changes or any 
other properties that would put them outside the 147.

Imagine I have an extent of Bourne.  That has a six-lead 
splice with King Edward.  King Edward is not one of the 147 
as it has an irregular lead end, but lets ignore that for 
the moment.  I can splice in 24 leads of King Edward 
whenever 2, 3, 4 or 5 pivot.

King Edward has a three-lead splice with Cambridge, and 
another one with Bourne.  I can use each of these to remove 
12 leads of King Edward by ringing Cambridge when the 6 is 
2nds or 5ths place bells, and Ipswich when the 6 is 3rds or 
6ths place bells.  All of the King Edward has now gone and 
I'm left with the familiar Cambridge, Ipswich, Bourne grid 
splice.

In that example, King Edward was just a device to explain 
the grid splice in terms of simpler splices.  By the 
end of the prodecure, the King Edward was entirely removed, 
so we're not concerned that it had an irregular lead head, 
thus taking it outside the 147.  In a similar way, we can 
introduce methods with other undesirable properties such as 
four blows in one place or jump changes, so long as we're 
careful to remove them again by the end.

Michael Foulds' books use methods with jump changes at the 
half lead quite extensively when explaining certain grid 
splices.  He refers to them as imaginary methods.

RAS