I shimmied into the 1844 corset one more time, pinned away all the excess I could, and marked the waistline. After carefully taking the corset off I measured all the pinned sections and wrote the amounts that needed to be removed from each pattern piece. Then I went to work blending the new points into the pattern's seam lines. To keep those lines nice and smooth and as true to the pattern as possible I lined a hip curve up to the seam line paying attention to the point where the reduction needed to be. Maybe a picture will help.
If you look at the numbers you can see the waist line hits the ruler at 9 1/8 inch, and there is a small red dot 1/4 inch in on the waistline. You can also see a red dot 1/2 inch from the seam line at the top edge of the panel. I need to connect these points. So I line the hip curve to the mark on the waist line at the 9 1/8 inch mark, then pivot the other end until it connects with the mark at the top.
After drawing the new curve in, and doing the same thing for all the other alterations needed, I've got my pattern. Here is it before being cut out, the blue highlighted areas will be trimmed off.
You can also see the waist line, which runs at an angle across two of the panels. Yikes. Thanks Mali, for suggesting a sturdy waist tape. I hadn't even thought of using a waist tape with this corset but I think it will be important so it doesn't stretch.
So now I have to unpick all the seams so I can recut the pieces. Normally I keep track of all seams I rip out, but do these count since I knew I'd be ripping them out?