 I'm a retired water engineer and it's my joy to work with so many talented volunteers who look after these wonderful steam engines. These are Hawthorne Davie steam engines and they are the last two working steam engines of their type in the whole world. They're two-stage steam engines and they would drive these shafts backwards and forwards rocking those huge cast iron wheels behind me round like that and they would be connected to rods that would lift enormous plunger pumps that would lift the sewage from 40 feet down from the end of the sewage collection systems and drive it down six 700 millimeter diameter mains to the what was then new sewage treatment works at Milton. Now the reason for this sewage pumping station is that at the end of the 1800s you could not swim in that river and survive because it was so filthy and so full of sewage. So many people in Cambridge were dying of cholera and this was the case in all of the major industrial cities throughout the world. So these new stations were the beginnings of us cleaning up our environment.