The book rest on top of the “Main box” is an unassuming feature. At first glance, it simply fills the space between the two compartment lids to either side. Only once those are opened, however, does the operator realize that there is more to behold. This video shows it in operation.
Construction-wise, there’s a bit more to it than simply mounting the hinges to the panel, and stop. It took a bit of trial-and-error to work things out to this point. Regardless, this is an elegant solution from the eighteenth century requiring only simple hardware. Features like this greatly enhance the overall value of the piece. Imagine being in the room when Oeben demonstrated this to the client. It’s almost magic!