Herbert Stumm is well known for his fine models of interesting and unusual engines and vehicles. This is a model of an engine by Leon Benier, Paris, France of 1888. It is usually referred to as a hot air engine, although Herbert explains that it is more like an ‘internal combustion’ engine that uses solid fuel. With each stroke, fresh air is pushed through the fire bed, expands and moves the working piston. A complex feeding mechanism continuously feeds coal onto the fire bed.