This mosaic (scroll down) shows the restored steam engine that powered a line of hot mills at Kidwelly. There was another such engine and set of mills to the left, in line with these mills, but it hasn't been restored. Unfortunately I hadn't visited the Science Museum in London yet, and was not too curious about how this engine worked. I'd guess the horizontal black pipe connects the engine to the boiler, and is the supply of hot steam. The large diameter green cylinder probably holds the piston, and the smaller green cylinder connected to the steam pipe may be the valve that routes the steam to first one side of the piston and then to the other, to produce reciprocating motion. The mechanism between the four, black, cylindrical legs converted the piston motion to rotation of the shaft driving the mills. NEXT LIST