I'd imagine it was used to keep the damp sheets of paper uniformly damp. In this picture (from Hornschuh's Orthotypographia) the guy to the right of the one standing up with the long cloak, seems to have a similar set-up, with two boards and some kind of block on top.

AI hallucinating again.....

Some beautiful pointing fingers here!

Just found a word that isn't in the OED : (to) affusk. If anyone knows what it means, I'd be very grateful! Here's the passage:

You make snail broth, of course, as per William Salmon's Family Dictionary (1695):

Yes : the British Museum (and for the last 4 years, apparently)

They seem to have got as far as south-west France (Hautefort)

In case there are any newbies (like me) out there who hadn't worked out how to visualise the comments that appear under a post but were too embarrassed to ask, here you are : you click not on the "respond" icon, but on the blank space just to the right of it (cf. picture). You're welcome.

Rats : I wasn't watching when it passed 23 million, but here we are