The Porter Brook is a river which flows through the City of Sheffield, England, descending over from its source on Burbage Moor to the west of the city to its mouth where it joins the River Sheaf in a culvert beneath Sheffield railway station. Like the other rivers in Sheffield, its steep gradient made it ideal for powering water mills and works associated with the metalworking and cutlery industries, and around 20 dams were constructed over the centuries to facilitate this. At its lower end, it is extensively culverted, but parts of it are gradually being restored to open channels, as part of a daylighting scheme for the city. The brook derives its name from its brownish colour, similar to the colour of Porter beer. Route Source The Porter Brook rises from a series of springs among the sedge grass of Burbage Moor, the highest of which is close to the contour near Brown Edge Farm. Its source is just inside the Peak District National Park, to the north-west of the village of Ringinglow. It passes through Clough Hollow, and under Fulwood Lane, where it leaves the National Park. Nearby, at the junction of Fulwood Lane and Greenhouse Lane is a Rotary Club funded toposcope, Finder Cairn, a rotary orientation table which indicates the direction of local landmarks. Porter Valley Beyond Fulwood Lane the brook flows into the Porter valley. The valley is divided into a series of five green and open spaces, created along the river valley between 1885 and 1938 and collectively known as the Porter Valley Parks. Just before it reaches the bridge carrying Woodcliffe over it, the river is joined by Mayfield Brook, which rises at a similar level but a little further to the north. Before the junction, Mayfield Brook supplied power to Fulwood corn mill, the highest mill on the system. Soon the combined flow reaches Forge Dam, now a large lake with an island. In Sheffield, "dam" referred to the body of water, rather than the structure which impounded it. Mills used for grinding were known as wheels, and the tail race was known as a goit. Beyond Forge Dam, where the Porter is defined as a main river, the brook passes Wire Mill Dam, where there is a monument celebrating the life of Thomas Boulsover, the inventor of Sheffield Plate. The grade II listed structure was constructed in 1927 by a Master