In the last instalment of the series, viewers get the chance to show off their ideas for hovercraft, ice lenses, scientific musical instruments and bar-snack separators - all responses to the challenges inspired by the scientific heroes examined by Adam Hart-Davis in the last six weeks. Hart-Davis also heads for the East Midlands, where he turns his bicycle into a spinning machine to demonstrate the invention of Richard Arkwright, whose own version replaced 96 skilled workers with just one operator. George Green, a miller from Nottingham, produced a brilliant and revolutionary mathematical tool that is still used to solve problems in maths and physics today. What was his inspiration? The final hero of the series is Isaac Newton. In his house at Woolsthorpe in Lincolnshire, Hart-Davis wonders if the great man might have invented the cat flap.