The River Irk is a small tributary of the River Irwell in Manchester. Originally on the surface it has been subsumed by the construction of Manchester Victoria Railway Station in the 19th century. The pictures shows a drainage system from Long Millgate into the Irk beneath Victoria Station. 1973
There is a video version of the exploration at http://youtu.be/7Q1aW0vUQ1Q
The Irk infamously was one of the most polluted and disease-ridden rivers in the world during the 18th and 19th century and feature in "The Moral and Physical Condition of the Working Classes employed in the cotton manufacture in Manchester" by James Phillips Kay 1832. It is no coincidence that Engel's was greatly influenced by what he saw around the Irk in Manchester, collaborating later with Marx on the communist manifesto in 1842.