The London Museum of Water & Steam is housed in the former Kew Bridge Pumping station, which opened in 1838. It houses the world’s largest collection of Cornish beam engines, including the world’s largest working beam engine. Four large working Cornish engines are in the museum’s main engine house and are operated for visitors.

Cornish beam steam engines were originally developed to pump water from Cornish copper mines in the 18th century.
A Cornish beam-engine house showing the engine in position. In simplistic terms, a piston inside the cylinder is moved by a combination of steam and atmospheric pressure. This, in turn, pulls the end of the beam down inside the engine house. If the other end of the beam is attached to pump rods in the shaft these are raised. On exhausting the cylinder, the pump rods are free to move downwards and it is this action that works the pumps in the shaft. Cylinders varied in size, and the engine can also be used to work winding and dressing machinery