This is a simple vertical engine of a type quite common in the early 20th century, but this one was made (I'm told) in the late 19th.
The wooden base (split, unfortunately) supports a simple firebox, on which sits the vertical boiler; 49mm x 67mm high. The boiler has no flue or tubes and the chimney is purely cosmetic. In addition to the dummy chimney, the top of the boiler has a safety valve and steam feed.
Steam is fed directly, via a short pipe, to the back of the port face of the oscillating cylinder. The cylinder is single acting; 6.5mm bore x 17.5 stroke. The crankshaft runs through the middle of the boiler, enclosed in a sealed tube. It has a simple crank at one end and a 55mm cast lead (?) spoked flywheel at the other.
Apart from the split in the wooden base (which still serves it's purpose adequately) the engine is in quite good condition, considering it's age. Paintwork appears to be original.