We have one instance of "poulces" that we have not translated: 113r: Then, with a <tl>small curved instrument</tl>, mark on the inside of the circle the thickness you want to give to the <tl>mold</tl>, which will be for a <al>common snake</al> as thick as two <ms><bp><fr>poulces</fr></bp></ms>, in order that when you throw in your <m>wetted sand</m>, you will see when it is thick enough. We always double tag "poulces" for <ms> and <bp> just to be safe, but do you think this snake is two "thumbs" thick or two "inches" thick? A snake that's two inches thick (as in, diameter) would be awfully big—I can't imagine that's what's meant here...
Decision: thumbs