I will also note (for reference) an observation on the pattern proceeding the page mentioning the Vincent "Square".
There appears to be some (additional) information and context I didn't initially understand ( It's absent in the accompanying notes for the pattern on https://archive.org/details/b1108865/page/n13, but is assumed to be something someone in tailoring profession of the relevant period would otherwise know ).
"A Beginner's First Course in Cutting " https://archive.org/details/Vincent.A.Beginners.First.Course.In.Cutting.Part.I.and.II.CPG/page/n7 (which was also authored by W.D.F Vincent.) seems to say that the "length of side" (outside leg?) is measured from a point above the "waist hollow" (And not from the actual waist), the text in the "Beginners Course" mentioning 'body rise' (a line 5 to 9 in the diagram here https://archive.org/details/b1108865/page/n13) ( 5 to 8 is what Seamly2D defines as N08- rise length side I think, but Vincent doesn't take this as a separate measure, seemingly calculating it from the lateral seat (hip) measure in some places, placing the 'wasit line' nominally about 2 inches below the 'top-line' according to the digram in the "Beginners Course" . Part 3 of the Cutter's Practical Guide also confirms this).
Once I'd figured this out I understand the pattern better. :slight_smile:, but understand I might have to adjust certain measures when drafting from these older patternsystems. ( Seamly2D being very well suited to them.)
It's noted by Vincent in the first linked work, that some trouser patterns may need a different seat angle to accommodate modified posture., This is notable in some of the modified patterns for things like riding pants , breeches and so on that follow..
I've actually learnt something today, so thanks for inspiring me to look a little deeper.
Observation 2 is far simpler, namely that some of Vincent's digrams include the seams, where as generally in Seamly2D, Seam allowances are made at the detail/layout stage.. Hmmm...
It may be worth adding a comment in the documentation about older pattern systems approaches, but as Vincent's system is at least 100 years old, It's hardly a priority, and so more recent systems should be fully documented first.