Silk satin & linen waistcoat. Early 19th century according to Kerry Taylor Auctions, but to me it looks much more 1780's. That closely spaced double breasted look is a very 80's style, and in the 1790's the 2 rows of buttons get much further apart.
The slanted collar and lack of big lapels do give it a somewhat early 19th century look, but I suspect this is altered from a longer waistcoat of at least a few decades earlier. The way the front edge curves just looks "off" for this later style, and the buttonholes appear to be the earlier style that are long and only partially opened, so you can have small buttons and a long decorative buttonhole. Very clever to just sew another row of buttons onto the ends to update the look!
Also you'll notice in the last picture that the linen thread used to whip the lining down around the buttonholes is the same weight as the stuff used to sew on the buttons, but a totally different colour!
The fact that the button threads are visible at all is another strong point in favour of it being altered, since the typical 18th century construction involves sewing the buttonholes and attaching the buttons before the lining is added, and we can see from the backs of the buttonholes that those were done in that order.
Anyways, the reason I wanted to post this in the first place is because I think the piecing is cool. Look at how economical they're being with their scraps! (Lots of extant garments are like this but it's no less delightful for being common.) The narrower strip at the side looks like it may have been added even later to accommodate growth, but the bit of linen that the pocket welt overlaps must have been there from the time it was cut down and updated.
I love the little triangle bit of piecing on the collar lining, but the most exciting scrap is the piece of ikat on the back of the collar!
