Holy logarithms, Batman! Could this be an ancient mechanism for calculating latitude? If they'd only take all their scans, toss it into a program to interpolate the missing bits, and manufacture a replica, then let one of us get ahold of it, they might just get an answer!
Given that latitude could not be calculated until the invention of a reliable clockwork mechanism, it's not unreasonable to posit that this might be a latitude calculator.
Great find, Aurore! Thank you!