A small, compact live steamer that's got surprising power and speed for its size. One of "Yankee Shop's" popular designs from the 1940s. Coal fired, Baker valve gear, slide valves dummied to look like piston valves. Copper boiler, 5-1/8" diameter. Axle pump, hand pump. Weighs around 90 pounds.
Here's what the prototype looked like. This is a Boston and Maine "Atlantic" in the 1940s, at Danvers Mass. What makes this photo particularly relevant to "live steam", is the man in the fireman's window. It's Carl Purinton. He was a fireman on the Boston and Maine, and was eventually promoted to Engineer. He was an Engineer for one day only, and then quit. He just "wanted to say that he had done it". The Engineer standing in the gangway in this view is Elmer Dean. Photo courtesy of Richard Symmes.
And here's the 3-1/2" gauge version. Richard Symmes runs his Yankee Shop/Friends Models 4-4-2 Atlantic at the track of Charlie Purinton in the 1980s. This particular engine has Walschaert valve gear custom-fitted by the builder; the Baker valve gear is standard on the original Yankee Shop design.
The Yankee Shop Atlantic, at speed. Click the photo to enlarge.
The 3/4" Atlantic fast approaches the camera. Click the photo to enlarge.
The Atlantic passes the camera. Click the photo to enlarge.