Looking at this picture, I'm reminded of Long Way Round, the documentary series following Ewan McGregor and Charley Boorman on a motorbike trip around the world. On more than one occasion the two remark on how they don't know this or that about the place they're in. Such is the case with this, taken in the Bytown Museum on Colonel By Day. Usually with a digital camera I'd photograph the display tag as a reminder of what it is for reference in a post, something that'll come in handy, for instance, in an art gallery. Instead I find myself looking at this picture and wondering, "so what was this about again?"
Anyway, the display has something to do with weights and measures, I think (fingers crossed), about blocks in the building of the Canal by Colonel By and his work crew.