I had planned to save this little nugget for when I posted about the outfit I'm making for a party on Saturday, but I already spilled the beans on Facebook. You may end up finding this less exciting than I do, but I'm kind of a nerd when it comes to this kind of thing!
I've spent the last few weeks studying late 1780s/early 1790s jackets (specifically 1787-1790). The two jackets I've taken as core inspiration are very similar in style. The striped jacket belongs to the Met, and the taupe brown jacket was sold by Auction House Coutau-Bégarie (and has been floating around Pinterest--unfortunately the link doesn't take you to the actual jacket).
Last night I was staring at the precious few images of the taupe jacket, thinking about how to attach the under bodice, when I noticed two triangular inserts in the back of the jacket, on either side of the "skirts". That's when I got really excited, because the same triangular inserts are on the striped jacket!! Two different jackets, undoubtedly made by different people in different places, but the same technique was used. It's a subtle addition, but would allow the skirts to flare out just a bit more from the rest of the jacket, since they're cut in one with the bodice pieces.
Even though my jacket is pretty much done (one more sleeve to attach, and buttons...), I'm going to figure out a way to put the triangular inserts into it.
So yeah. Excuse my geekery! ;-)
Screenshot of the Met jacket, showing triangular inserts:
Picture of the back of the taupe jacket, showing triangular inserts (harder to see because the fabric is solid, but they're there!):