I've been meaning to post more pics of that shelf bracing, mentioned in the thread "holy crap, high end furniture assembled with nails everywhere". I don't know if you had realized exactly how the shelf was braced, or if yo u could surmise how, i.e., by an underside board, that rests on the notched side-pieces. And, of course, that board is adjustable.
Here's a pic of my cabinet's bracing:
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Scroll right for 2 more pics showing the early 1800s cabinet, that I got th e idea from. This cabinet is my brother's. I, nor he, remembers the cab inet makers name and I have no idea if he invented this bracing technique. The cabinet maker is/was American, though.
Sonny