I think this engine was designed by George Carlson. I found this engine while surfing the web and here is a link to the plans to build this engine http://www.homemetalshopclub.org/projects/scotchx2/scotchx2.html

 

I modified this engine by making the frame as one piece and adding cylinder heads. By doing this i made sure that the cylinders were in line with one another. This engine was my second steam engine and one i would recommend it to anybody. This engine runs very smooth and slow when run on about 10psi.