Museum archaeologists excavating Manchester Dock have been pleased to find the inner walls of the lock gate are in very good condition. Many of the stones not only feature the original chisel marks but also the identifying marks of the individual masons. Stonemasons would mark the stones they had dressed so their daily output could be accurately tallied and they would be paid accordingly.
Some are simple shapes (like the triangle one featured on our Flickr page). Others are a mix of letters and numbers like this example.