Geograph - photograph every grid square

Volunteer Ben is working the slide valve by hand to get Princess running smoothly in the right direction. He will then kick loose the mechanism holding the eccentric rod up. It will then engage the gab and the engine will become self acting. There is a real knack to the timing as the valve has to be reversed over the dead centres. Miss the timing and the engine will stall and even run backwards. Later in the afternoon a new volunteer was being put through her paces but I didn't take any shots of her.