As the previous article Power Trip explains, not everyone is convinced of the need for running times longer than required for, say, a weekend, when one’s regular watch might not be in use from Friday until Monday morning. With the increasing popularity of watch-winders, the issue only concerns rarely wound timepieces: an automatic in regular, daily use precludes any concerns about power reserve.
With reference to Thomas Tompion’s year-going table clock, ‘The Mostyn’, now residing in the British Museum, watchmaker Peter Roberts says: “There was a period in the late-19th century when quite a few ‘one-year-running’ duration power-reserve clocks were made and the clockmakers explored all the possibilities for achieving this: heavier weights, a lightweight train, high count pinions, as low friction as possible and a very slow-frequency oscillator, or pendulum.
“In a watch, you can use a powerful mainspring with a single large barrel or multiple barrels, you can reduce the friction by possibly using new materials, you can fit lightweight components, a high-count lightweight train and – the most difficult to achieve – you can have a very low-speed escapement oscillator system.”
Roberts warns, however, that, “most of these practices work directly against achieving good timekeeping”. He adds, wryly: “Of course, a self-winding automatic mechanism fitted to a modern wristwatch with a running time of 72 hours makes the whole idea unnecessary.” Here are eight of the world’s current super-powers.