The second in our series of interviews with Michael Bennet-Levy looks at the Steuart’s Patent vacuum tank regulator – a clock produced in 1923 that its makers, J & D Meek, claimed was accurate to “better than a second a year.” If true this would have made it the most accurate timekeeper in the world prior to the invention of Caesium clocks in the mid 1950s. The essence of the Steuart regulator is that the electric motor drives the clock and the pendulum governs and corrects the speed of the motor. Neither is connected. Ideal for telescopes (because it doesn't tick), the clock was used as a stand-in for Big Ben during WWII and in the opinion of the Scientific American it marked “the most important development in clock-making which has taken place in modern times.”

Check out the video to see why this clock is so special or catch up with out first interview with Michael Bennet-Levy as he discusses the world's first HDTV.