This two cylindered engine is based on a
design for a four cylindered (steam?) engine patented by William Siemens
in 1863 in which a nutating
plate driven by a ball ended rod fitting into a socketed disc crank, interconnects
a circle of axial pistons - the phase relationships between the pistons
being the same as their angular position in the circle.
Thus two cylinders 90 degs apart can be
used as the power cylinder and the air chamber of a Stirling engine.
Less frictional losses than a swashplate drive
but at the expense of far greater complexity, with ball and socket joints
throughout..
(See also the Nutator)
