Simon.
Cylindercover cooling.
I realize we haven`t gone into details on this subject. The coolingwater enter the cylindercover via pipebends from the cylinder coolingjackets. The pipebends would the only visible part ( if at all). Out of the cover it enters the series/parallel coolingwater cock ( blue) which allow the water to go to the exhaustvalve cage, either partly (parallel) or all (series) depending upon the temperate reading on the thermometer, it is manually controlled.
The water from the cock then goes to the exhaust manifold coolingspace. The funny looking "spring" on the photo is, I believe, the handle for the cock, the springshape is a typical 1920/30 solution for heat insulation. The details to be seen are a bit unclear to me on this.
Tore