This is a detail from the carved memorial tablet of Joseph Priestley, the chief engineer of the Leeds/Liverpool Canal Company.
Work on the canal began after an act of parliament was passed in 1770, but the project was not fully completed until forty years later. The canal carried coal and textiles across the Pennines and through Lancashire to the port of Liverpool. Bradford had its own link to this canal.
The memorial can be found on the wall of Bradford Cathedral. I don't think you need me to tell you which one of the three figures is Mr. Priestley!