Geograph - photograph every grid square

This is on the vertical compound engine 'Elizabeth' from Clough House Mill, Slaithwaite. This is part of the Lumb's governor regulating the engine's speed and is to Wilby's patent. Basically, it is a feedback mechanism that alters the length of the linkage between the governor and the valve gear (either throttle or cut-off governing)so that the governor returns to its middle position and the engine to its design speed. This acts to neutralise the speed variation as the load changes. The former Birmingham Museum of Science and Industry had one of these set up for demonstration purposes and the public could press buttons to increase or decrease the 'load' and watch this amazing widget compensate. The note of the driving motor also changed as an audible indication. The museum also published a photocopied 'museograph' that explained how this worked. Sadly, the governor is now in a store and museographs are not available at the new Thinktank museum.