Stumped on 1911 Trouser pattern

[LonoftheNB]

I'm extremely new to flat pattern drafting and I've been trying to follow the instructions in the book Short Methods Cutting, Designing and Manufacturing men's clothing from The Charles Publishing Co. and I started out doing alright but, now I'm stuck with finding I and determining the curve for hip/waist on the forepart.
The instruction says A to I is 1-12or42 seat, and I to K is 1/2 waist

I'm not really sure of what I'm supposed to do there to determine I



I had originally started with a pattern from the book New Standard Trousers and Breeches systems from 1908 since I wanted to do something in around late 1890s but, I got stuck with that in a similar spot since I didn't have the tool and trying to math my way through didn't work so well.

I would try to get this by referencing actual fitting pants but, I don't own anything that could help with this.

I'd appreciate any advice that could help me get this draft to mock up phase. Thank you

[Gerry]

Perhaps it's a misprint? Possibly it should read J to I = 1/12th of seat. I - K would be 1/4 of the waist (not one half), because we're dealing with a single panel (four in total and the waist circumference is divided equally between them).

[LonoftheNB]

I'll try that thank you

[TSjursen]

You square out from the big stylised A to find the line along which you place I and K. When you have the line simply measure out 1/12 (half) seat to find I, then from here on 1/2 (half) waist.

[TTailor]

Remember that these old drafts use the tailor’s square,  so 1/2 of whatever measurement indicated so a 42 inch hip means using 21 on the square.
If you are manually calculating it is 1/12 of 21 or 1/2 of half the waist measurement

[LonoftheNB]

Thank y'all for the incredibly helpful advice. I have something I think is workable for the first mock-up. I'm starting the back part today applying what I've learned.





I was curious tho. Is there a quick reference guide for figuring these measurements manually? I have a tailor's square that's helped me through this process for the most part within my limited knowledge base but, it's not one of those that has all the scales marked out. Thanks to a folded paper trick the book I'm following now offered I was able to mark out with tape 1/4, 1/8, 1/16, and 1/32 but, the other pattern I started with wanted 1/6 and I'm not really sure of where to begin to figure that one since my first instinct kinda failed me and I ended up with a draft with no rise.

[Greger]

Take your seat measure and divide in half - Scale - take a strip of paper and mark out one third of that. If you fold that in half you got 1/6. Another fold gives 1/12. One more fold becomes 1/24.
Always mark off the end of measuring device. By doing so it adds just a bit more than if you mark off a mark on the "ruler".
Add the proper inlays on the cloth.

[LonoftheNB]

Thank you I really appreciate it. I'm learning so much I went from barely able to process all these lines to logically grasping what does what. That said while the back is going smoother I'm stuck again. I think it's another one of those misprints. I can't find Y and my attempts to try and work around it don't really look right.

[TTailor]

Y is on the front waistline and I think it should read J to Y is 1/3 seat (on the square)

If you don't have a tailors square with the markings, you can just use a calculator since that is what the square is.

So take half your seat measurement, then divide by 6 to find 1/6 seat on the square.

I have a post on my blog that deals with some of this terminology
http://atailormadeit.blogspot.com/2011/09/trouser-drafting-terminology.html

[SO_tailor]

I understand I am late to this post but what it means by "A — I is 1 — 12" is that A — I is the measurement from 1 — 12. Let's say, that 1 — 12 is 18", well then A — I would be that measurement as well. Hope that helps the next time you draft! Regards