Help with a large induction coil secondary

[Lynton]

I am about to build an induction coil in the traditional manner, after "A. T. Hare".
The dimensions intimated in the book are confusing and imply there are 96 pies 3/16" each or
18" long - this is the length of the core, and the book indicates around 13" between ends of coils.
The book also indicates thicker pies at the centre and thinner at ends,( following lines of magnetic force).
However the dimensions given in the Appendix are considerably removed from that indicated in the text and the drawing given.
My main question is "how important is the thicker/thinner pies to performance ?"
Can anyone assist please

Lynton

 

[berkeman]

Sorry, what does the term "pies" mean in this context? Is it turns/cm? Or some other measure?

Can you post a diagram or links to what you have been reading? Thanks.