This opens with waves crashing against the cliffs as if it were straight out of a Daphne du Maurier novel as we pan to ruined stannaries and scarred terrain. All we really need now is Leslie Banks and Charles Laughton. Sadly, no - not quite. Instead we are taken on a tour of the really quite precarious mines of Cornwall that are long since abandoned. There are still one or two pumping engines working, and these are massive great things of an intricate design that you can imagine will work forever. Over the years, the miners have searched for tin, arsenic and copper in the past, but now they mostly work above ground using high-powered jets of water to filter out some fine clay for use in the ceramics industry. The pumping rods can weigh over 100 tons and stretch some 2000 feet down into the ground as they labour relentlessly removing the constant flow of seepage underground away and making it safer for the people. The engine that drives this piston uses steam and now using some illustrations we learn a little more of the history of the development and evolution of this life-saving and ground-breaking technology. The science here is fascinating, but the narration is so dreadfully monotonic that it doesn't really help enliven what is essentially quite an interesting explanation of not just Cornish engines, but of the whole principles, and dangers, of steam propulsion. Still, it includes the influences of Papin and his boiling to give an international dimension to the ingenuity on display hereto and it's worth half an hour if you're remotely interested in this, or anything steam powered.