By Julius de Waal

External simplicity, but really unusual inside. Try to imagine two nested, rectangular pistons in a rectangular cylinder. The inner cylinder is guided by the crankshaft and moves vertically, the outer cylinder moves horizontally. The steam distribution is handled by a rotating shell slider. Sounds like total blockage, but runs very smoothly.

The machine was originally described by J.B.Root in Scientific America of March 26, 1864

Julius’ drawings are based on a model created by R.S.Hedin.

Click on drawings to download - for personal use only.