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John A
Are you confident a purely mechanical watch/clock wouldn’t be equally affected by lightning.  Long ago when all watches were mechanical and people would pay to have them mended, watch repairers would say “Oh it must have become magnetised”, and high-class watchmakers would claim that their watches could not be affected by magnetism.  Whether this was true or all myth and marketing, I know not.  I was only a little lad.  Certainly, WW2 bomb disposal teams were able to use electro-magnetic ‘clock-stoppers’ to stop clockwork time fuses running down.  Even if a lightning bolt didn’t completely stop a clock or watch it might well induce a touch of temporary hard iron magnetism in any parts containing traces of ferro-magnetic material such as the hairspring and the main-spring, which would muck up your weeks of careful rating.  Certainly any aircraft struck by lightning had to be compass swung at close intervals afterwards as any induced temporary hard-iron magnetisn gradually dissipated.  DaveP