Waistcoat 1: drafting a pattern

I have a waistcoat pattern that I've used several times before - the Laughing Moon #109 frock coat with waistcoat (I've also used the frock coat pattern, early in my sewing career, and at that point vowed I'd never make another frock coat; now I can't wait to make more). This time, however, I decided to draft my own pattern. I wanted two things: first of all, to have the back fit properly, without needing an adjustable belt, and second to have a basic pattern block that I could alter to make different styles of waistcoat.

Interestingly, although he gives detailed drafting directions for trousers and coats, Jason Maclochlainn doesn't describe how to draft a waistcoat in The Victorian Tailor. I will definitely be using his description for tailoring the garment, but to draft it I turned to The Cutter's Practical Guide to ...Waistcoats, &ct. (seriously, could these titles be any longer?). As happened the last time I drafted a pattern, I was cruising along, following the directions perfectly, and then suddenly nothing made sense anymore. The points referred to in the text didn't match the pictures. The text went from well-defined blocks of directions to one long, run-on paragraph containing several steps at once:

Now take Vincent's Registered Square, and place the angle line sloping down ¼ in front, and with the corner on point 2¼, and draw line up to A, and make 2¼ to A the front shoulder measure less ¼in., having deducted the width of back neck; so that in this case O to A is 9¾, that quantity being arrived at as follows 12½ less ¼ equals 12¼; from this take 2½ for the back neck, and you get 9¾. From 2¼ to 9 apply the over-shoulder measure less ½ E of the back, Diagram 3. Thus: ½ to E 8½ leaves 8½, but from this we also take ¼in., as with the front shoulder. The width of the shoulder from A to B is made ¼in. less than back from ¾ to 6, Diagram 3. Now shape scye from B to O.

 Riiiight. Never mind that all of the points referenced (the numbers) are based on an example set of measurements, and that your numbers will all be different.

I muddled through somehow, and ended up with a pattern that looked like the one in the example (except for the slightly rounded midsection to accommodate my slightly rounded midsection). I cut out a quick muslin, and discovered very quickly that having a personal tailor's form of my body would be great. I have a mannequin body that my wife got for me from the trash (yay, trash!), but he's a little manlier in the shoulders and chest than I am, so this form-fitting pattern won't fit him.

I also found that the images of taking measurements show having the measurements taken over a waistcoat on purpose. You're supposed to wear the garment you're measuring for. Which seems a little odd to me, but then again it makes sense that you're then basically copying the measurements of a garment that you know fits you. I had only been wearing a shirt when I was measured, so the waistcoat was pretty snug.

The last thing I discovered is that I can't draw an armscye to save my life.

 The final image here is of the altered armscye that will actually fit around my arms (it's a little lower I think than the example diagram expects it to be, but I'll be able to play with that later). I reduced the height of the back of the neck. I'm also going to add some seam allowances on some of the edges to give it a little more play.

The next step will be to make a test garment in muslin before I finalise my pattern. That will also allow me to make pattern pieces for the other bits of the waistcoat that aren't in the initial draft: the collar, the facings, the lining, the canvas, and the pockets and pocket welts.