Nauticalia

Robert Stirling invented his "hot air" engine in 1816, using an inter-cylinder air-exchange system. Because the heat source is external to the mechanical parts there are no explosions, so his design was very smooth, quiet and safe - but no commercial application was found until a recent reawakening of interest for localised power generation. This delightful working model is powered by alcohol (meths) burners that sit in oval slots to allow adjustment of the engine speed; one fill lasts about 30 minutes. The two cylinders are heated at opposite ends of the cycle, giving a very smooth, fast operation; the interlinked rocker arms are reminiscent of 19th century "nodding donkey" swing beam pumps.

They are superbly made and the quality is evident the moment you open the box, whether you choose the kit (takes 1-2hrs, all parts fully machined) or the factory-built model. Fascinating to watch. Base is 6x4", height 6".