 As high-pressure steam is admitted to one side of the high-pressure cylinder, the low-pressure steam exhausted from the other side is passed through the valves to the opposite side of the engine and into the low-pressure cylinder; finally the exhaust steam from the opposite side of the low-pressure cylinder escapes through the center part of the valve to the blastpipe.The high- and low-pressure cylinders were mounted in vertical line with each other, with the piston rods in parallel.Usually the low-pressure cylinder was on the bottom, but clearance issues sometimes caused it to be put on the top.